Network Working Group X. Wu
Internet-Draft H. Schulzrinne
Expires: August 18, 2005 Columbia University
February 14, 2005
LESS: Language for End System Services in Internet Telephony
draft-wu-iptel-less-00
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Abstract
In Internet telephony, end systems can take a large role in providing
services, especially in networks without pre-configured
infra-structure, such as peer-to-peer networks. Since we believe
that end system services differ in their requirements from network
services, we define a new service creation scripting language called
the Language for End System Services (LESS). LESS inherits many
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characteristics from the Call Processing Language (CPL). It contains
commands and events for direct user interaction and the control of
media applications. This document defines the basic elements of LESS
and several commonly used LESS extensions.
Table of Contents
1 Introduction ........................................ 7
1.1 Conventions of This Document ........................ 7
2 LESS design decisions ............................... 8
2.1 High-level Structure ................................ 8
2.2 Simplicity .......................................... 9
2.2.1 Familiarity ......................................... 9
2.2.2 Generality .......................................... 10
2.2.3 Uniformity .......................................... 10
2.2.4 Analyzability ....................................... 11
2.3 Safety .............................................. 11
2.3.1 Type safety ......................................... 11
2.3.2 Control flow safety ................................. 12
2.3.3 Memory access ....................................... 12
2.3.4 LESS engine safety .................................. 13
2.3.5 Using third-party created or auto-generated
service scripts ..................................... 13
3 LESS elements ....................................... 13
4 Variables ........................................... 15
4.1 System information .................................. 15
4.2 User information .................................... 15
4.3 Agent information ................................... 15
4.4 Trigger information ................................. 16
4.5 Action information .................................. 16
5 Basic LESS elements ................................. 16
5.1 Triggers ............................................ 16
5.1.1 "incoming" trigger .................................. 16
5.1.2 "timer" trigger ..................................... 16
5.2 Switches ............................................ 17
5.2.1 "time-switch" ....................................... 17
5.2.2 "address-switch" .................................... 17
5.2.3 "priority-switch" ................................... 17
5.2.4 "string-switch" ..................................... 17
5.2.5 "language-switch" ................................... 18
5.2.6 "status-switch" ..................................... 18
5.3 Modifiers ........................................... 19
5.3.1 "location" Modifier ................................. 19
5.3.2 Location Lookup ..................................... 19
5.3.3 Location Removal .................................... 19
5.4 Actions ............................................. 19
5.4.1 "accept" ............................................ 19
5.4.2 "reject" ............................................ 20
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5.4.3 "redirect" .......................................... 20
5.4.4 "authenticate" ...................................... 20
5.4.5 "call" .............................................. 21
5.4.6 "terminate" ......................................... 21
5.4.7 "mail" .............................................. 22
5.4.8 "log" ............................................... 22
5.4.9 "wait" .............................................. 23
6 Subactions and Ancillary Information ................ 23
7 Security Considerations ............................. 23
8 IANA Considerations ................................. 23
8.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less ......................... 24
8.2 Schema registration ................................. 24
8.3 MIME Registration ................................... 24
9 LESS Extensions ..................................... 25
10 Media handling extension ............................ 26
10.1 Modifiers ........................................... 26
10.1.1 "Media:media" Modifier .............................. 26
10.2 Actions ............................................. 27
10.2.1 "Media:mediaupdate" Action .......................... 27
10.3 IANA Considerations ................................. 27
10.3.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:media ................... 28
10.3.2 Schema registration ................................. 28
10.3.3 MIME Registration ................................... 28
11 Mid-call Handling extension ......................... 29
11.1 Actions ............................................. 29
11.1.1 "Midcall:transfer" Action ........................... 29
11.1.2 "Midcall:merge" Action .............................. 30
11.2 IANA Considerations ................................. 30
11.2.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:midcall ................. 30
11.2.2 Schema registration ................................. 31
11.2.3 MIME Registration ................................... 31
12 User Interaction extension .......................... 31
12.1 Triggers ............................................ 31
12.1.1 "UI:command" Trigger ................................ 31
12.2 Actions ............................................. 32
12.2.1 "UI:alert" Action ................................... 32
12.2.2 "UI:getinput" Action ................................ 33
12.3 IANA Considerations ................................. 33
12.3.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:ui ...................... 33
12.3.2 Schema registration ................................. 34
12.3.3 MIME Registration ................................... 34
13 Instant Messaging extension ......................... 34
13.1 Triggers ............................................ 34
13.1.1 "IM:message" Trigger ................................ 34
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13.2 Actions ............................................. 35
13.2.1 "IM:sendmsg" Action ................................. 35
13.3 IANA Considerations ................................. 35
13.3.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:im ...................... 36
13.3.2 Schema registration ................................. 36
13.3.3 MIME Registration ................................... 37
14 Event Handling extension ............................ 37
14.1 Triggers ............................................ 37
14.1.1 "Event:subscription" Trigger ........................ 37
14.1.2 "Event:notification" Trigger ........................ 37
14.2 Switches ............................................ 37
14.2.1 "Event:event-switch" Switch ......................... 37
14.3 Actions ............................................. 38
14.3.1 "Event:approve" Action .............................. 38
14.3.2 "Event:deny" Action ................................. 38
14.3.3 "Event:defer" Action ................................ 39
14.3.4 "Event:subscribe" Action ............................ 39
14.3.5 "Event:notify" Action ............................... 40
14.4 IANA Considerations ................................. 41
14.4.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:event ................... 41
14.4.2 Schema registration ................................. 42
14.4.3 MIME Registration ................................... 42
15 Location-based service extension .................... 42
15.1 Switches ............................................ 42
15.1.1 "Location:where-switch" Switch ...................... 43
15.1.2 "Location:where-relation-switch" .................... 45
15.2 IANA Considerations ................................. 47
15.2.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:location ................ 47
15.2.2 Schema registration ................................. 47
15.2.3 MIME Registration ................................... 48
16 Queue handling extension ............................ 48
16.1 Actions ............................................. 48
16.1.1 "Queue:enqueue" Action .............................. 48
16.1.2 "Queue:dequeue" Action .............................. 48
17 Examples ............................................ 49
17.1 Q.1211 services ..................................... 49
17.1.1 Abbreviated dialing (ABD) ........................... 49
17.1.2 Attendant (ATT) ..................................... 50
17.1.3 Authentication (AUTC) ............................... 50
17.1.4 Authorization code (AUTZ) ........................... 51
17.1.5 Automatic call back (ACB) ........................... 51
17.1.6 Call distribution (CD) .............................. 52
17.1.7 Call forwarding (CF) ................................ 52
17.1.8 Call forwarding on busy/don't answer (CFC) .......... 52
17.1.9 Call gapping (GAP) .................................. 53
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17.1.10 Call hold with announcement (CHA) ................... 53
17.1.11 Call limiter (LIM) .................................. 54
17.1.12 Call logging (LOG) .................................. 55
17.1.13 Call queueing (QUE) ................................. 55
17.1.14 Call transfer (TRA) ................................. 56
17.1.15 Call waiting (CW) ................................... 56
17.1.16 Closed user group (CUG) ............................. 57
17.1.17 Consultation calling (COC) .......................... 57
17.1.18 Customer profile management (CPM) ................... 57
17.1.19 Customer recorded announcement (CRA) ................ 57
17.1.20 Customized ringing (CRG) ............................ 58
17.1.21 Destination user prompter (DUP) ..................... 59
17.1.22 Follow-me diversion (FMD) ........................... 59
17.1.23 Mass calling (MAS) .................................. 59
17.1.24 Meet-me conference (MMC) ............................ 59
17.1.25 Multi-way calling (MWC) ............................. 60
17.1.26 Off-net access (OFA) ................................ 60
17.1.27 Off-net calling (ONC) ............................... 60
17.1.28 One number (ONE) .................................... 61
17.1.29 Origin dependent routing (ODR) ...................... 61
17.1.30 Originating call screening (OCS) .................... 62
17.1.31 Originating user prompter (OUP) ..................... 62
17.1.32 Personal numbering (PN) ............................. 62
17.1.33 Premium charging (PRMC) ............................. 62
17.1.34 Private numbering plan (PNP) ........................ 63
17.1.35 Reverse charging (REVC) ............................. 63
17.1.36 Split charging (SPLC) ............................... 63
17.1.37 Terminating call screening (TCS) .................... 63
17.1.38 Time dependent routing (TDR) ........................ 64
17.2 5ESS services ....................................... 64
17.2.1 Attendant call transfer (also known as Call
splitting) .......................................... 64
17.2.2 Attendant camp-on ................................... 65
17.2.3 Attendant conference ................................ 66
17.2.4 Authorization code .................................. 67
17.2.5 Automatic recall .................................... 67
17.2.6 Call forwarding busy line (CFBL) .................... 68
17.2.7 Call forwarding busy line--incoming only ............ 69
17.2.8 Call forwarding--don't answer ....................... 69
17.2.9 Unconditional call forwarding ....................... 70
17.2.10 Call hold ........................................... 70
17.2.11 Call transfer--individual--all calls ................ 70
17.2.12 Call waiting and cancel call waiting ................ 71
17.2.13 Circle hunting ...................................... 72
17.2.14 Conference calling .................................. 72
17.2.15 Customer-changeable speed calling ................... 72
17.2.16 Direct connect ...................................... 73
17.2.17 Distinctive ringing ................................. 73
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17.2.18 Four- and eight-party ............................... 74
17.2.19 Recorded telephone dictation ........................ 74
17.2.20 Time-of-Day features ................................ 75
17.2.21 Message services .................................... 75
17.2.22 Multibutton key telephone system (MBKS) ............. 76
17.2.23 Group alerting ...................................... 76
17.3 Services defined in CSTA Phase III .................. 77
17.3.1 Accept call ......................................... 78
17.3.2 Alternate call ...................................... 78
17.3.3 Answer call ......................................... 78
17.3.4 Call back call-related .............................. 78
17.3.5 Call back message call-related ...................... 78
17.3.6 Camp on call ........................................ 79
17.3.7 Clear call .......................................... 79
17.3.8 Clear connection .................................... 79
17.3.9 Conference call ..................................... 80
17.3.10 Consultation call ................................... 80
17.3.11 Deflect call ........................................ 80
17.3.12 Dial digits ......................................... 80
17.3.13 Directed pickup call ................................ 80
17.3.14 Group pickup call ................................... 80
17.3.15 Hold call ........................................... 80
17.3.16 Intrude call ........................................ 81
17.3.17 Join call ........................................... 81
17.3.18 Make call ........................................... 81
17.3.19 Make predictive call ................................ 81
17.3.20 Park call ........................................... 82
17.3.21 Reconnect call ...................................... 82
17.3.22 Retrieve call ....................................... 82
17.3.23 Send message ........................................ 82
17.3.24 Single step conference call ......................... 82
17.3.25 Single step transfer call ........................... 82
17.3.26 Transfer call ....................................... 83
17.4 New services ........................................ 83
17.4.1 Email ............................................... 83
17.4.2 Web ................................................. 83
17.4.3 Instant messaging ................................... 84
17.4.4 Event subscription and notification ................. 84
17.4.5 Event notification and event-based services ......... 85
17.4.6 Location-based services ............................. 85
18 Feature Interaction Handling Algorithm for LESS
Scripts ............................................. 86
18.1 Tree merging algorithm .............................. 86
19 The XML Schema for LESS and Commonly Used
Extensions .......................................... 89
19.1 XML Schema for LESS ................................. 89
19.2 XML Schema for LESS Media Extension ................. 104
19.3 XML Schema for LESS Mid-call handling Extension ..... 119
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19.4 XML Schema for LESS User Interaction Extension ...... 121
19.5 XML Schema for LESS Instant Messaging Extension ..... 123
19.6 XML Schema for LESS Event Handling Extension ........ 124
19.7 XML Schema for LESS Location-based Services
Extension ........................................... 128
19.8 XML Schema for LESS Queue Handling Extension ........ 134
20 References .......................................... 136
20.1 Normative References ................................ 136
20.2 Informative References .............................. 137
Authors' Addresses .................................... 137
Intellectual Property and Copyright Statements ........ 139
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1 Introduction
One of the key promises of Internet telephony lies in the ability of
developing and deploying innovative services rapidly and efficiently.
Internet telephony services are not limited to those performed in
servers operated by service providers; end systems can play a much
larger role in providing services than in traditional telephone
networks.
We define end systems as the systems that are located at the end of a
session signaling routing path and can initiate or accept session
setup messages. By this definition, end systems are not limited to
the user-operated systems, instead, they can also be conference
servers. Accordingly, we define network servers as the entities that
perform session message routing. We believe it is necessary to define
a service creation language specifically for end systems because end
system services are different from network services.
There are services that are clearly implementable only in end systems
or in network, but most can be moved to either location, or split
between the two. Providing services in user-operated end systems has
the advantage that on-the-spot interaction with users is much easier.
Network services can only interact via protocol messages and possibly
media content, rather than GUIs. It might be possible to incorporate
user interaction into scripts running in servers, but it is likely to
be far more cumbersome and subject to network delays.
In Internet telephony, usually end systems are the only entities
where signaling and media flows converge. This is different from the
legacy PSTN. Thus, any service that requires interaction with user
media is likely to be easier to implement in end systems. The more
detailed analysis on the differences between end system services and
network services can be found in our articles [11] [12].
Because of the differences between end system services and network
services, we define the Language for End System Services specifically
for end system service creation. Section 2 introduces the design
decisions for LESS. Section 3 briefly describe the categories of
elements in LESS, we then provide more detailed description of the
elements in each category in the following sections. Extensibility
is very important for a service creation language. Section 9 defines
how to write LESS extensions. Several commonly used extensions are
defined in the following sections. Section 17 provides service
examples written in LESS. Section 19 shows the XML schema of the
language.
1.1 Conventions of This Document
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In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
indicate requirement levels for compliant LESS implementations.
Some paragraphs are indented, like this; they give
motivations of design choices, advice to implementors, or
thoughts on future development of or extensions to LESS.
They are not essential to the specification of the
language, and are non-normative.
2 LESS design decisions
The goal of the language is to allow end users to program their own
communication services with little training in a graphical service
creation environment. To achieve the goal, the language must
represent a high-level abstraction of communication behaviors. The
elements in the language must have semantic meanings. The language
has to be simple and safe. The Call Processing Language (CPL) [2] has
all the above features. However, CPL is originally designed for
network servers, such as SIP proxy servers. It lacks of the functions
for end system services, e.g., accepting calls, making outgoing
calls, and interacting with users. CPL does not have variables,
which is very important for call decision making and user
interactions. We have LESS inherit the basic structure and many
elements from CPL and enhance it with more elements for end system
services.
In this section, we first provide the high-level structure of LESS.
We then analyze the simplicity and safety of the design rules.
2.1 High-level Structure
As shown in Figure 1, we consider that every service starts with a
trigger invoked, such as an incoming call, an event notification, a
user interaction event, or a timer event. The service will then check
its current context, such as user status, device status, and the
status related to the trigger. We name the check points as switches,
which can branch call decisions. Once a service gets its matching
condition, it will perform pre-defined actions, e.g., accepting an
incoming call, holding an existing call, or sending an instant
message. We use modifiers to provide parameters to actions, e.g.,
media modifier to define media information of a call action.
Additional actions may get performed based on the result of an
action.
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+--------+
| +-------+
|modifier| |
| |<------+
* +---+----+
* * |
* * V
========= * * +------+
( trigger )--->* switch*------>|action|---+
========= * * +--+---+ |
* * |
* *<--------------------+
*
Figure 1: The high-level structure of LESS
The above high-level abstraction makes LESS having a tree-like
structure, as shown in Figure 2. The tree-like structure makes LESS
easy to analyze and safe for service programming.
2.2 Simplicity
"The fewer concepts to understand in a language the better" [13],
though, in some cases two smaller concepts might be simpler and more
flexible than one more powerful but complicated concept. For example,
separating commonly used action arguments, such as people's contact
locations, as modifiers is better than putting the arguments into
every action.
"Simplicity enters in four disguises: uniformity (rules are few and
simple), generality (a small number of general functions provide as
special cases of more specialized functions), familiarity (familiar
symbols and usages are adopted whenever possible), and brevity
(economy of expression is sought)" [14]. For LESS, we consider
analyzability is more important than brevity because LESS is an XML-
based language designed for communication services and has people
without programming experience as its target users. In communication
service creation, users may encounter feature interaction [15]
problems, how to analyze and solve feature interactions is essential
for users to create usable services. We discuss the familiarity,
generality, uniformity, and analyzability of LESS below.
2.2.1 Familiarity
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+----------+
| incoming | (trigger)
+-----+----+
|
|
+----------+------------+
|Is the sender's address| (switch)
| sip:bob@example.com? |
+----------**-----------+
/ |
YES NO
/ |
+------* +---*-----------------------+
|accept| |Is the priority of the call| (switch)
+------+ | greater than 'normal'? |
(action) +--------**-----------------+
/ |
YES NO
/ |
+---*-+ +--*------------------+
|alert| |redirect to voicemail|
+-----+ +---------------------+
(action) (action)
Figure 2: Sample decision tree
The familiarity requires a language not to violate common use of
notation. We choose to use the Extensible Markup Language (XML) [3]
to define LESS, uses the datatypes defined in XML schema. By this
way, the elements defined in LESS all have semantic meaning and easy
for users to understand and remember.
2.2.2 Generality
The generality requires a language to have a small number of general
elements. The special elements of the language can be introduced by
specializing the general elements. As illustrated in Section 2.1,
LESS has only four kinds of elements, namely triggers, switches,
actions, and modifiers. Every new element defined in LESS extensions
must fall in one kind of the elements. In another words, in LESS's
XML schema, LESS will have four basic abstract elements, namely
'trigger', every element must be a substitutionGroup of one of the
four abstract elements.
2.2.3 Uniformity
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The uniformity requires a language with few and simple rules. There
are only four rules in LESS. The rules can be summarized below:
Trigger rule: A LESS script gets invoked if and only if one of
its triggers get matched. A trigger must be the root of a
decision tree. Two triggers with the same name and
attributes cannot appear in the same script.
Switch rule: Only switches can branch call decisions. One switch
have no more than two branches. A switch must be a child of
a trigger or another switch in a decision tree.
Action rule: Only actions can change call status and call
context and only actions can be LESS decision tree leaves.
There can be subsequent actions after one action. No
triggers can follow an action.
Modifier rule: A modifier can only be used as the parent element
of actions to enforce the actions.
2.2.4 Analyzability
Another aspect of language simplicity is how easy to analyze a
program written by the language. For LESS, we are more interested in
how LESS handling feature interaction problems in communication
services. As discussed in our technical report "Feature Interactions
in Internet Telephony End Systems" [15], we can handle feature
interaction problems among LESS scripts by the action conflict tables
and the tree merging algorithm defined in the technical report. The
process is straight-forward, and can also help to solve detected
interactions.
2.3 Safety
Since LESS will be used by people without programming experience, we
may expect errors that seem naive by experienced programmers. We
should also expect that people may use third-party created malicious
service scripts. The language design should help people to prevent
errors and protect people from malicious scripts. The error
prevention mechanisms for LESS fall into two categories, one is to
put restrictions on the language itself, the other is to put
restrictions on LESS engines. We are more interested in the
restrictions on the language itself since that is directly related to
the language design. The restrictions on LESS engines may cause
service portability problem so we should try to prevent errors in the
language design whenever possible.
2.3.1 Type safety
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Type checking is a very effective way in catching programming errors,
from the trivial errors, such as misspelled identifiers, to the
fairly deep errors, such as violations of data structure invariants.
LESS is an XML-based language and uses XML schema [4] to define its
elements. "The strong typing mechanism in XML Schema, along with the
large set of intrinsic types and the ability to create user-defined
types, provides for a high level of type safety in instance
documents. This feature can be used to express more strict data type
constraints, such as those of attribute values, when using XML Schema
for validation." [4]
In LESS, there are no user defined variables so only static type
checking is needed. There are many advantages to have a statically
type-checked language. Static type checking can provide earlier, and
usually more accurate information on programmer errors. It can
eliminate the need for run-time checks, which may slow program
execution. Statically type-checked language may be less expressive
than dynamically type-checked language, however, since LESS is not
designed to handle all communication services and targets to end
users, safety is more important than expressiveness.
2.3.2 Control flow safety
LESS has a tree-like structure for call decision making. LESS does
not allow a tree node to back-reference to its ancestors or itself.
This means there is no loop or recursion in LESS scripts, and will
exclude the possibility of non-terminating or non-decidable LESS
scripts. However, LESS still provides some mechanisms for repeated
events handling. The timer trigger can get invoked periodically. The
lookup modifier implies that follow-up actions are applied to every
location in the result set.
Run-time feature interactions may confuse users. The LESS trigger
rule ensures that a specific trigger can appear no more than once in
a LESS script thus helps to avoid run-time feature interactions in
the LESS script. The LESS service creation environment should help
users to merge multiple service scripts into one as illustrated in
the technical report on feature interaction handling in LESS [15].
2.3.3 Memory access
A language can be described as unsafe in that the language allows
some means to access memory directly. In LESS, there are no pointers,
no direct memory accesses, and even no user-defined variables. LESS
has maximum string length defined in its XML schema for every element
with string type to prevent buffer overflow attack. If a user put a
very long string in a service script, the service script will be
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considered invalid when checking against the LESS XML schema.
2.3.4 LESS engine safety
LESS engine developers can do several things to enhance the safety of
LESS scripts. The developers must make sure that every trigger has
default behaviors defined. If a trigger gets invoked in a LESS
engine, but there is no actions defined for the matching context, the
LESS engine must perform the default actions for that trigger. This
ensures every LESS script is decidable.
LESS is different from CPL [2] when dealing with user trustiness. CPL
is designed for running on signaling servers, such as SIP proxy
servers. The safety consideration for CPL ensures that semi-trusted
users cannot create malicious or incompetent service scripts to
interrupt other users' services, including crashing the server,
revealing security-sensitive information, and causing denial of
service. While LESS is used on users' end devices, usually, it does
not need to handle the interference of other users. LESS engine need
to ensure safe resource usages, such as CPU usage. It needs to define
how deep a decision tree can be, what is the minimum interval for
timer trigger, and whether it can control multimedia devices.
2.3.5 Using third-party created or auto-generated service scripts
Sometimes, end users may not be aware of a new service or they may
not know how to create a service, the service scripts auto-generated
by feature learning, or created by third-parties, may bring great
conveniences to users. However, end users have to check the safety of
the third-party created or auto-generated scripts, for example, to
make sure that the scripts will not crash their systems or forward
their calls to unwanted parties.
The safety consideration discussed in previous sections can be
applied to third-party or auto-generated service scripts. In
addition, the simplicity and the tree-like structure of LESS make it
viable to convert any valid LESS scripts into graphical
representation of decision trees. This is a big advantage of LESS
for end users to do safety checking. Users do not have to check LESS
programs line by line, instead, they can watch the graphical
representation and easily find out what actions a service script will
perform.
3 LESS elements
As we discussed earlier, LESS has four kinds of elements, namely
triggers, switches, actions, and modifiers.
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A trigger is an entry point to every service. It is the same as the
toplevelactions defined in CPL. The basic LESS definition has two
triggers, "incoming" (Section 5.1.1) and "timer" (Section 5.1.2).
Note that we do not have "outgoing" trigger, which is defined in CPL.
Because in end systems, an outgoing call is usually triggered by some
user interactions, e.g., pressing a call button. This is different
from that in an outbound server, in which "outgoing" triggered by
receiving an outgoing call signaling message. We defined user
interaction extension, which has one trigger, "UI:command" (Section
12.1.1). The event handling extension has two triggers,
"Event:notification" (Section 14.1.2) and , "Event:subscription"
(Section 14.1.1). The instant messaging extension has one trigger,
"Message:message" (Section 13.1.1).
Switches branch call decisions. This is the same as CPL switches.
The basic LESS definition has six switches, namely "time-switch"
(Section 5.2.1), "address-switch" (Section 5.2.2), "language-switch"
(Section 5.2.5), "priority-switch" (Section 5.2.3), "string-switch"
(Section 5.2.4), and "status-switch" (Section 5.2.6). The location-
based service extension has two switches, "where-switch" (Section
15.1.1) and "where-relation-switch" (Section 15.1.2). The event
handling extension has one switch, "event-switch" (Section 14.2.1).
Actions represent users' decision for trigger handling. This is
similar to CPL actions, but we allow multiple actions be executed in
parallel and in sequential. Each action has a "next" output. Actions
in an action's "next" output will be executed after the action. If
multiple actions have the same parent tag, they are executed in
parallel.
The basic LESS definition has six signaling actions, namely "accept"
(Section 5.4.1), "reject" (Section 5.4.2), "redirect" (Section
5.4.3), "authenticate" (Section 5.4.4), "call" (Section 5.4.5), and
"terminate" (Section 5.4.6). It also has three non-signaling
actions, "mail" (Section 5.4.7) "log" (Section 5.4.8), and "wait"
(Section 5.4.9).
We defined a mid-call handling extension. It has two actions,
"Midcall:transfer" (Section 11.1.1), and "Midcall:merge" (Section
11.1.2). The user interaction extension has two actions, "UI:alert"
(Section 12.2.1). "UI:getinput" (Section 12.2.2). The instant
messaging extension has one action, "IM:sendmsg" (Section 13.2.1).
The event handling extension has five actions, "Event:subscribe"
(Section 14.3.4), "Event:notify" (Section 14.3.5), "Event:approve"
(Section 14.3.1), "Event:deny" (Section 14.3.2), and "Event:defer"
(Section 14.3.3). The queue handling extension has two actions,
"Queue:enqueue" (Section 16.1.1), and "Queue:dequeue" (Section
16.1.2).
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Modifiers provide action parameters. We have three modifiers defined
in basic LESS definition, namely "location" (Section 5.3.1), "lookup"
(Section 5.3.2), and "remove-location" (Section 5.3.3). In media
handling extension, we defined "media" (Section 10.1.1) modifier.
4 Variables
LESS does not allow user-defined variables, however, it allows
several pre-defined variables to retrieve system information, user
information, agent information, trigger information, and action
information. The variables can be used in descriptive messages, such
as the reason parameter of a reject message. We use the format
'variable-name' to represent a variable in a LESS script. For
example, in a "reject" action, we can provide its reason parameter as
below.
<reject code="486" reason="Sorry, I am {user.activity}">
4.1 System information
system.bandwidth represents the bandwidth of the end system
running the script.
4.2 User information
user.presence represents script owner's online/offline
information.
user.activity represents script owner's current activity.
Activity values are defined as in the Rich Presence
Extensions to the Presence Information Data Format (RPID)
[5].
user.mood represents script owner's current mood. Mood values
are defined as in RPID.
user.location represents script owner's physical location.
user.language represents script owner's preferred language.
4.3 Agent information
agent.number-of-calls represents the number of existing calls in
the user agent running the script.
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agent.media-capabilities represents the media capabilities in
the user agent running the script.
4.4 Trigger information
trigger.origin represents the originator of a trigger's
signaling message.
trigger.destination represents the destination of a trigger's
signaling message.
trigger.priority represents the priority of a trigger's
signaling message.
trigger.timestamp represents when the signaling message is
received.
trigger.subject represents the subject of a trigger's signaling
message.
4.5 Action information
action.last-action-result represents the return value of last
actions. Every action may return a value. In this
document, if the return value is not specified, the return
value will be empty.
5 Basic LESS elements
5.1 Triggers
5.1.1 "incoming" trigger
The "incoming" trigger is the same as that defined in CPL [2],
Section 2.1.
5.1.2 "timer" trigger
The "timer" trigger is to handle timer-based events, e.g.,
automatically making an outgoing call at a specific time. The "timer"
trigger has the same attributes as those defined in "time-switch"
(Section 5.2.1). Their syntax is shown in Figure 3.
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Trigger: "timer"
Parameters: "dtstart" Start of interval (RFC 2445 DATE-TIME)
"dtend" End of interval (RFC 2445 DATE-TIME)
"duration" Length of interval (RFC 2445 DURATION)
"freq" Frequency of recurrence ("secondly",
"minutely", "hourly", "daily",
"weekly", "monthly", or "yearly")
"interval" How often the recurrence repeats
"until" Bound of recurrence (RFC 2445 DATE-TIME)
"count" Number of occurrences of recurrence
"bysecond" List of seconds within a minute
"byminute" List of minutes within an hour
"byhour" List of hours of the day
"byday" List of days of the week
"bymonthday" List of days of the month
"byyearday" List of days of the year
"byweekno" List of weeks of the year
"bymonth" List of months of the year
"wkst" First day of the work week
"bysetpos" List of values within
set of events specified
Figure 3: Syntax of the "timer" trigger
5.2 Switches
5.2.1 "time-switch"
The "time-switch" is the same as that defined in CPL [2], Section
4.4.
5.2.2 "address-switch"
The "address-switch" is the same as that defined in CPL [2], Section
4.1.
5.2.3 "priority-switch"
The "priority-switch" is the same as that defined in CPL [2], Section
4.5.
5.2.4 "string-switch"
The "string-switch" is the same as that defined in CPL [2], Section
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4.2.
5.2.5 "language-switch"
The "language-switch" is the same as that defined in CPL [2], Section
4.3.
5.2.6 "status-switch"
Status-switches allow a LESS script to make decisions based on the
status of the script owner, or other people whose status can be
acquired. The syntax of "status-switch" is summarized in Figure 4.
Node: "status-switch"
Outputs: "status" Specific status to match
Parameters: "uri" The principal's URI
"status-name" The name of the status to check. Available
values are "active-calls", "activity",
"mood", and "presence".
Output: "status"
Parameters: "greater" Used for "active-calls"
"less" Used for "active-calls"
"equal" Used for "active-calls"
"is" Exact match, not for "active-calls"
"contains" Not for "active-calls"
Figure 4: Syntax of the "status-switch" node
"status-switch" takes two parameter. "uri" indicates the URI of the
principal for status checking. If omited, the principal for checking
will be the script owner. "status-name" indicates what status to
check. It has four possible values:
"active-calls" checks for ongoing active calls.
"presence" checks for online/offline status of the principal.
"mood" checks for the mood of the principal.
"activity" checks for the activity of the principal.
The "status" output takes five parameters, indicating different
conditions to match. The "greater", "less", and "equal" can only be
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used for "active-calls", indicating whether the number of active
calls is greater than, less than, or equal to a specific value. The
"is" parameter takes a list of strings for its value. User status
MUST equal to all the strings in the list for being matched. The
"contains" parameter also takes a list of strings for match. if user
status equals to any string in the list, the switch get matched.
5.3 Modifiers
5.3.1 "location" Modifier
The "location" modifier is the same as that defined in CPL [2],
Section 5.1.
5.3.2 Location Lookup
The "lookup" modifier is the same as that defined in CPL [2], Section
5.2.
5.3.3 Location Removal
The "remove-location" modifier is the same as that defined in CPL
[2], Section 5.3.
5.4 Actions
As we discussed before, LESS allows multiple actions get executed
sequentially or in parallel. Every LESS action will have a default
output "next". In the following sections, we will omit this default
output for the syntax of actions.
5.4.1 "accept"
"accept" actions cause the user agent to accept an incoming call.
Their syntax is shown in Figure 5.
Node: "accept"
Outputs: None
Next node: None
Parameters: None
Figure 5: Syntax of the "accept" node
There is no parameters for the "accept" action. We can use "media"
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modifier to change "accept" action's media parameters, as described
in Section 10.1.1.
5.4.2 "reject"
The "reject" modifier is the same as that defined in CPL [2], Section
6.3.
5.4.3 "redirect"
The "redirect" modifier is the same as that defined in CPL [2],
Section 6.2.
5.4.4 "authenticate"
"authenticate" actions cause user agents to authenticate local users
or remote users. Their syntax is shown in Figure 6.
Node: "authenticate"
Outputs: "success" Next node if authentication succeeded
"failure" Next node if authentication failed
Parameters: "method" Authentication method to use. Possible values
are "basic" and "digest".
"realm" The realm for authentication challenge.
"user" Required user for authentication.
"target" Which party to authenticate. Possible values
are "remote" and "local".
Output: "success"
Parameters: none
Output: "failure"
Parameters: none
Figure 6: Syntax of the "authenticate" node
"authenticate" action takes four arguments: "method", "realm", "user"
and "target". The default value for "method" is "digest", which
representing digest authentication.
The action has two outputs, "success" and "failure", handles the
situation under which the authentication succeeds or fails,
accordingly.
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5.4.5 "call"
"call" actions cause the user agent to make an outgoing call. Their
syntax is shown in Figure 7.
Node: "call"
Outputs: "accepted" Next node if call attempt get accepted.
"busy" Next node if call attempt returned "busy".
"failure" Next node if call attempt failed.
"noanswer" Next node if call attempt was not
answered before timeout.
"redirection" Next node if call attempt was redirected.
Parameters: "timeout" Time to try before giving up call attempt.
Output: "accepted"
Parameters: none
Output: "busy"
Parameters: none
Output: "noanswer"
Parameters: none
Output: "failure"
Parameters: none
Output: "redirection"
Parameters: none
Figure 7: Syntax of the "call" node
The "call" action has one parameter, "timeout", which specifies the
time, as a positive integer number of seconds, to wait for the call
attempt. We can also use "media" modifier to change "call" action's
media parameters, as described in Section 10.1.1.
The "call" action has five outputs. The "accepted" is followed if the
call was accepted; the "busy" is followed if the call was busy; the
"noanswer" is followed if the call was not answered before the
"timeout" parameter expired; the "failure" is followed if the call
failed for any other reason; the "redirection" is followed if the
call was redirected.
5.4.6 "terminate"
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"terminate" actions cause the user agent to terminate one or more
ongoing sessions or call attempts. Their syntax is shown in Figure
8.
Node: "terminate"
Outputs: None
Next node: None
Parameters: "uri" Select calls to terminate based on
the "uri" list.
"subject" Select calls to terminate based on
the "subject" list.
"calls" Possible values are "all", "last",
and "this". Default value is "this".
Figure 8: Syntax of the "terminate" node
There are three parameters for the "terminate" action, which define
how to select calls to terminate. If "uri" parameter presented, all
calls to one of the "uri" values will get terminated. If "subject"
parameter presented, all calls with one of the "subject" values will
get terminated. If the "calls" parameter is "all", all calls matching
"uri" and "subject" parameters will get terminated, if it is "last",
the last established session will get terminated, if it is "this",
the calls associated with the trigger event of the script will get
terminated.
5.4.7 "mail"
The "mail" action is the same as that defined in CPL [2], Section
7.1.
5.4.8 "log"
The "log" action is similar to that defined in CPL [2], Section 7.2.
But we added a new parameter for recording a call. The recording
parameter makes it easy to associate a log with a recorded call.
Their new syntax is shown in Figure 9.
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Node: "log"
Outputs: None
Next node: Any node
Parameters: "name" Name of the log file to use
"comment" Comment to be placed in log file
"recording" The URI to place recording files
Figure 9: Syntax of the "log" node
5.4.9 "wait"
"wait" actions cause the user agent to perform subsequent actions in
the "next" output after a duration of time. Their syntax is shown in
Figure 10.
Node: "wait"
Outputs: None
Next node: Any node
Parameters: "duration" Time to wait
Figure 10: Syntax of the "wait" node
6 Subactions and Ancillary Information
Subactions and ancillary information are the same as those defined in
CPL Section 8 and Section 9.
7 Security Considerations
LESS shares the same security considerations as CPL, as defined in
CPL document [2], Section 13.
8 IANA Considerations
This document registers a new MIME type, application/less+xml, and a
new URN per RFC 2141 [6], RFC 2648 [7], and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less will only refer to the
version of LESS in this document and will not change. Any LESS
enhancements MUST be made by extensions and MUST have different
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namespaces.
8.1 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:less
URI: urn:ietf:params:xml:ns:less
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
8.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.1.
8.3 MIME Registration
As an XML type, LESS's MIME registration conforms with "XML Media
Types," RFC 3023 [9].
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MIME media type name: application
MIME subtype name: less+xml
Mandatory parameters: none
Optional parameters: charset
As for application/xml in RFC 3023.
Encoding considerations: As for application/xml in RFC 3023.
Security considerations: See Section 7, and Section 10 of RFC
3023.
Interoperability considerations: Different user agents may use
incompatible address types. However, all potential
interoperability issues should be resolvable at the time a
script is uploaded; there should be no interoperability
issues which cannot be detected until runtime.
Published specification: This document.
Applications which use this media type: SIP user agents.
Additional information:
Magic number: None
File extension: .less or .xml
Macintosh file type code: "TEXT"
Person and e-mail address for further information:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
Intended usage: COMMON
Author/Change Controller: The IETF.
9 LESS Extensions
User agents MAY support additional LESS features beyond those listed
in this document. LESS extensions are indicated by XML namespaces
[10]. Every extension MUST have an appropriate XML namespace assigned
to it. The XML namespace of the extension MUST be different from the
XML namespace defined in Section 15.2. The extension MUST NOT change
the syntax or semantics of the basic LESS schema defined in this
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document. All XML tags and attributes that are part of the extension
MUST be appropriately qualified so as to place them within that
namespace.
A LESS script SHOULD NOT specify any namespaces it does not use. For
compatibility with non-namespace-aware parsers, a LESS script MAY
omit the base LESS namespace for a script which does not use any
extensions.
A LESS server MUST reject any script which contains a reference to a
namespace which it does not understand. It MUST reject any script
which contains an extension tag or attribute which is not qualified
to be in an appropriate namespace.
In the XML schema of LESS, we introduce four abstract elements,
namely `trigger', `switch', `action', and `modifier', which
accordingly have the abstract type `TriggerType', `SwitchType',
`ActionType', and 'ModifierType'. Any trigger in a LESS extension
MUST be defined as the substitutionGroup of the abstract `trigger'
element, and has the type extended from the `TriggerType'. Any
switch in a LESS extension MUST be defined as the substitutionGroup
of the abstract `switch' element, and has the type extended from the
`SwitchType'. Any action in a LESS extension MUST be defined as the
substitutionGroup of the abstract `action' element, and has the type
extended from the `ActionType'. Any modifier in a LESS extension
MUST be defined as the substitutionGroup of the abstract `modifier'
element, and has the type extended from the `ModifierType'.
We defined several commonly used extensions that are very important
for LESS-based services as below.
10 Media handling extension
Media handling extensions define the elements that can manipulate
session media information.
10.1 Modifiers
10.1.1 "Media:media" Modifier
"Media:media" modifiers specify what media to use for an signaling
action, such as "accept" and "call", as well as the parameters of the
media. Their syntax is shown in Figure 11.
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Node: "Media:media"
Outputs: None (Next node follows directly)
Next node: Any node
Parameters: "media" A list of medias. Possible values are "audio",
and "video".
"input" The source of input. It can be "microphone",
for audio, "camera" for video, or a URL
to a media file.
"mode" Possible values are "sendonly", "recvonly",
"sendrecv", and "inactive".
"codec" The codec used for the media.
Figure 11: Syntax of the "Media:media" node
10.2 Actions
10.2.1 "Media:mediaupdate" Action
"Media:mediaupdate" actions cause the user agent to change the media
setup for an ongoing session. Their syntax is shown in Figure 12.
Node: "mediaupdate"
Outputs: None
Next node: None
Parameters: None
Figure 12: Syntax of the "mediaupdate" node
There is no parameters for the "mediaupdate" action. We can use
"media" modifier to change "mediaupdate" action's media parameters,
as described in Section 10.1.1. "Media:mediaupdate" actions can be
used to handle some mid-call handling services, such as "mute" and
"hold".
10.3 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:media will only refer
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to the version of LESS media extension in this document and will not
change. Any other LESS enhancements MUST be made by extensions and
MUST have different namespaces.
10.3.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:media
URI: urn:ietf:params:xml:ns:less:media
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Media Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Media Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:media</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
10.3.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:media
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
10.3.3 MIME Registration
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LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
11 Mid-call Handling extension
Mid-call handling actions can manipulate ongoing sessions. As we
discussed before, "Media:mediaupdate" can handle "mute" and "hold"
services. This extension defines two new actions, namely
"Midcall:transfer" and "Midcall:merge".
11.1 Actions
11.1.1 "Midcall:transfer" Action
"Midcall:transfer" actions cause the user agent to transfer existing
calls to another user. Their syntax is shown in Figure 13.
Node: "Midcall:transfer"
Outputs: "accepted" Next node if "transfer" was accepted.
"busy" Next node if "transfer" returned "busy".
"failure" Next node if "transfer" failed.
"noanswer" Next node if "transfer" was not
answered before timeout.
"redirection" Next node if "transfer" was redirected.
Parameters: "timeout" Time to try before giving up "transfer".
Output: "accepted"
Parameters: none
Output: "busy"
Parameters: none
Output: "noanswer"
Parameters: none
Output: "failure"
Parameters: none
Output: "redirection"
Parameters: none
Figure 13: Syntax of the "Midcall:transfer" node
The "Midcall:transfer" action takes the same parameter and outputs as
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"call" action, as defined in Section 5.4.5.
11.1.2 "Midcall:merge" Action
"Midcall:merge" actions will merge multiple calls into an end system
hosted conference. By default, audio streams will be mixed and sent
to all the call participants. Video streams are forwarded to all the
call participants. If there are held or muted calls, the hold and
mute status are kept. Their syntax is shown in Figure 14.
Node: "Midcall:merge"
Outputs: None
Next node: None
Parameters: "uri" Select calls to merge based on the "uri" list.
"subject" Select calls to merge based on
the "subject" list.
Figure 14: Syntax of the "Midcall:merge" node
There are two parameters for the "Midcall:merge" action, which define
how to select calls to merge. If "uri" parameter presented, all calls
to one of the "uri" values will be merged. If "subject" parameter
presented, all calls with the one of the "subject" values will be
merged. If further calls want to get merged into an existing end
system hosted conference, users can use any value in "uri" list or
"subject" list to refer to an existing conference.
11.2 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:midcall will only refer
to the version of LESS mid-call handling extension in this document
and will not change. Any other LESS enhancements MUST be made by
extensions and MUST have different namespaces.
11.2.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:midcall
URI: urn:ietf:params:xml:ns:less:midcall
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
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XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Mid-call Handling Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Mid-call Handling Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:midcall</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
11.2.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:midcall
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
11.2.3 MIME Registration
LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
12 User Interaction extension
User Interaction extension handles user inputs and perform actions
for alerting users and getting user inputs. It has one trigger and
two actions defined.
12.1 Triggers
12.1.1 "UI:command" Trigger
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"UI:command" handles user invoked commands, such as pressing call
button, hold button, or transfer button. Their syntax is shown in
Figure 15.
Trigger: "UI:command"
Parameters: "command" Command name to match.
Figure 15: Syntax of the "UI:command" trigger
"UI:command" trigger takes one parameter, "command", to check the
command to match. Commands can be "call", "hold", "mute", "transfer",
or any other commands users may perform. Usually, a command is
associated with a user interface button.
12.2 Actions
12.2.1 "UI:alert" Action
"UI:alert" actions play alerting messages. Their syntax is shown in
Figure 16.
Node: "UI:alert"
Outputs: "timeout" Next node if alerting time exceeds that
specified in "duration" parameter.
Parameters: "duration" Time to play alerting message before
stopping alert.
"priority" Priority of alerting. Possible values
are "emergency", "urgent", "normal",
and "non-urgent".
"icon" The icon to display on the alerting interface.
"message" The message to display on the alerting interface.
"style" Possible alerting styles. Can be a combination of
"vibrate", "sound", "flash",
and "text". By default, it is "sound".
"input" Play a file as specified in the "input" URI.
Output: "timeout"
Parameters: none
Figure 16: Syntax of the "UI:alert" node
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12.2.2 "UI:getinput" Action
"UI:getinput" actions acquire users' input. Their syntax is shown in
Figure 17.
Node: "UI:getinput"
Outputs: "noanswer" Next node if no input after the time
specified in "timeout" parameter.
Parameters: "timeout" Time to wait for user input.
"source" Input source, possible values are
"screen" and "sound".
"target" Get input from "local" or "remote" user.
Return value: Return a text string acquired from user input.
Output: "noanswer"
Parameters: none
Figure 17: Syntax of the "UI:getinput" node
12.3 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:ui will only refer to
the version of LESS mid-call handling extension in this document and
will not change. Any other LESS enhancements MUST be made by
extensions and MUST have different namespaces.
12.3.1 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:less:ui
URI: urn:ietf:params:xml:ns:less:ui
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
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BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>User Interaction Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the User Interaction Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:ui</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
12.3.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:ui
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
12.3.3 MIME Registration
LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
13 Instant Messaging extension
13.1 Triggers
13.1.1 "IM:message" Trigger
"IM:message" handles incoming instant messages. Their syntax is
shown in Figure 18.
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Trigger: "IM:message"
Parameters: None
Figure 18: Syntax of the "IM:message" trigger
13.2 Actions
13.2.1 "IM:sendmsg" Action
"IM:sendmsg" actions cause the user agent to send an outgoing instant
message. Their syntax is shown in Figure 19.
Node: "IM:sendmsg"
Outputs: "accepted" Next node if the message get accepted.
"failure" Next node if failed to send the message.
"noanswer" Next node if no response for the message
before timeout.
"redirection" Next node if the message was redirected.
Parameters: "timeout" Time to try before giving up sending message.
Output: "accepted"
Parameters: none
Output: "noanswer"
Parameters: none
Output: "failure"
Parameters: none
Output: "redirection"
Parameters: none
Figure 19: Syntax of the "IM:sendmsg" node
The parameters and outputs of "IM:sendmsg" actions are the same those
for "call" actions, as defined in Section 5.4.5.
13.3 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
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and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:im will only refer to
the version of LESS mid-call handling extension in this document and
will not change. Any other LESS enhancements MUST be made by
extensions and MUST have different namespaces.
13.3.1 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:less:im
URI: urn:ietf:params:xml:ns:less:im
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Instant Messaging Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Instant Messaging Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:im</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
13.3.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:im
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
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13.3.3 MIME Registration
LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
14 Event Handling extension
Event handling extension is used to handle event subscriptions and
notifications. It has two triggers, one switch, and five actions
defined.
14.1 Triggers
14.1.1 "Event:subscription" Trigger
"Event:subscription" handles incoming event subscription. Their
syntax is shown in Figure 20.
Trigger: "Event:subscription"
Parameters: None
Figure 20: Syntax of the "Event:subscription" trigger
14.1.2 "Event:notification" Trigger
"Event:notification" handles incoming event notification. Their
syntax is shown in Figure 21.
Trigger: "Event:notification"
Parameters: None
Figure 21: Syntax of the "Event:notification" trigger
14.2 Switches
14.2.1 "Event:event-switch" Switch
Event-switches allow a LESS script to make decisions based on the
event values in an incoming event subscription or notification. The
syntax of "event-switch" is summarized in Figure 22.
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Node: "Event:event-switch"
Outputs: "event" Specific event to match
Parameters: None
Output: "event"
Parameters: "package" Match against a list of event packages.
"is" Match against an event list.
Figure 22: Syntax of the "Event:event-switch" node
The "event" output takes two parameters, "package" checks whether an
event has a specific package name, "is" checks whether an event is
one of the event specified in the event list.
14.3 Actions
14.3.1 "Event:approve" Action
"Event:approve" actions cause the presence agent to approve an
incoming event subscription. Their syntax is shown in Figure 23.
Node: "Event:approve"
Outputs: None
Next node: None
Parameters: "expires" Expiration duration for the subscription.
Figure 23: Syntax of the "Event:approve" node
14.3.2 "Event:deny" Action
"Event:deny" actions cause the presence agent to deny an incoming
event subscription. Their syntax is shown in Figure 24.
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Node: "Event:deny"
Outputs: None
Next node: None
Parameters: None
Figure 24: Syntax of the "Event:deny" node
There are no parameters and outputs for the "Event:deny" action.
14.3.3 "Event:defer" Action
"Event:defer" actions cause the presence agent to defer the decision
on an incoming event subscription. This will cause the event
subscription in pending state. Their syntax is shown in Figure 25.
Node: "Event:defer"
Outputs: None
Next node: None
Parameters: None
Figure 25: Syntax of the "Event:defer" node
There are no parameters and outputs for the "Event:defer" action.
14.3.4 "Event:subscribe" Action
"Event:subscribe" actions cause the presence agent to send an event
subscription to a presentity. Their syntax is shown in Figure 26.
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Node: "Event:subscribe"
Outputs: "approved" Next node if the subscription was approved.
"denied" Next node if the subscription was denied.
"pending" Next node if the subscription was pending.
"noanswer" Next node if the subscription was not
answered before timeout.
"failure" Next node if the subscription failed for
any other reasons.
"redirection" Next node if the subscription was redirected.
Parameters: "timeout" Time to try before giving up the subscription.
"expires" The duration of the subscription.
"package" The event package to subscribe to.
"content" The content (e.g., event filtering) in subscription.
Output: "approved"
Parameters: none
Output: "denied"
Parameters: none
Output: "pending"
Parameters: none
Output: "noanswer"
Parameters: none
Output: "failure"
Parameters: none
Output: "redirection"
Parameters: none
Figure 26: Syntax of the "Event:subscribe" node
14.3.5 "Event:notify" Action
"Event:notify" actions cause the presence agent to send an event
subscription to a presentity. Their syntax is shown in Figure 27.
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Node: "Event:notify"
Outputs: "accepted" Next node if the notification was accepted.
"noanswer" Next node if the notification was not
confirmed before timeout.
"failure" Next node if the notification failed for
any other reasons.
"redirection" Next node if the notification was redirected.
Parameters: "timeout" Time to try before giving up the notification.
"package" The event package in notification.
"event" The event in notification.
"##any" Any other parameters for an event.
Output: "accepted"
Parameters: none
Output: "noanswer"
Parameters: none
Output: "failure"
Parameters: none
Output: "redirection"
Parameters: none
Figure 27: Syntax of the "Event:notify" node
14.4 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:event will only refer
to the version of LESS mid-call handling extension in this document
and will not change. Any other LESS enhancements MUST be made by
extensions and MUST have different namespaces.
14.4.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:event
URI: urn:ietf:params:xml:ns:less:event
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
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XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Event Handling Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Event Handling Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:event</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
14.4.2 Schema registration
This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:event
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
14.4.3 MIME Registration
LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
15 Location-based service extension
This extension introduces two new switch nodes named where-switch and
where-relation-switch. The new switch nodes check people's physical
locations and based on the location information to make call control
decisions.
15.1 Switches
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15.1.1 "Location:where-switch" Switch
"Where-switches" allow a LESS script to make call decisions based on
the physical location information. They are summarized in Figure 28.
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Node: "Location:where-switch"
Outputs: "where" Specific the location to match
Parameters: "type" "geospatial", "civil"
"uri" the location occupier's uri. If omited,
check the script owner's location.
Output: "where"
Parameters: "longitude" Longitude coordinates,
valid only for geospatial type
"latitude" Latitude coordinates,
valid only for geospatial type
"altitude" Altitude coordinates,
valid only for geospatial type
"country" Country of the location,
valid only for civil type
"A1" National subdivisions
(state, region, province, prefecture),
valid only for civil type
"A2" County, parish, gun (JP), district (IN),
valid only for civil type
"A3" City, township, shi (JP),
valid only for civil type
"A4" City division, borough, city district, ward,
chou (JP), valid only for civil type
"A5" neighborhood, block,
valid only for civil type
"A6" street, valid only for civil type
"PRD" Leading street direction,
valid only for civil type
"POD" Trailing street suffix,
valid only for civil type
"STS" Street suffix, valid only for civil type
"HNO" House number, numeric part only,
valid only for civil type
"HNS" House number suffix,
valid only for civil type
"LMK" Landmark or vanity address,
valid only for civil type
"LOC" Additional location information, such as room
valid only for civil type
"FLR" Floor, valid only for civil type
"NAM" Name (residence, business or office occupant)
valid only for civil type
"PC" Postal code, valid only for civil type
"distance" Distance value to a specified location.
Valid only if geospatial or
civil location presented.
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"condition" Valid only if distance presented.
Value is (in|out|at|). Default value is "at".
"unit" Valid only if distance presented.
Value is (m|km|mi|in|ft|yd|naut mi).
Default value is "m".
"direction" Direction relative to a specified location,
Valid only if geospatial or
civil location presented. Value is
"(south|north|west|east|above|below)".
Figure 28: Syntax of the "Location:where-switch" node
Location:where-switches have two node parameters: The mandatory
parameter "type" specifies the location type to match: either
geospatial location, or civil location. The optional parameter "uri"
specifies the location occupier's uri. If not provided, the location
occupier will be the script owner.
The "where" output tag may have one or more parameters, indicating
the exact location to match.
The "longitude", "latitude", and "altitude" are used to specify a
geographical location. The country, "A1", "A2", "A3", "A4", "A5",
"A6", "PRD", "POD", "STS", "HNO", "HNS", "LMK", "LOC", "FLR", "NAM",
and "PC" are used to specify a civil location.
The "distance" parameter cannot be used without geographical location
or civil location specified. Usually, the distance parameter is used
with geographical location since it is difficult to measure the
distance to a civil location. The "condition" and "unit" parameters
are used to provide more convenient ways for distance specification.
The available unit values are (m|km|mi|in|ft|yd|naut mi), mapped to
meter, kilometer, mile, inch, foot, yard, and nautical mile,
accordingly.
The "direction" parameter cannot be used without geographical
location or civil location specified. The value "south" or "north"
are usually used when latitude specified. The value "east" or "west"
are usually used when longitude specified. The value "above" and
"below" are usually used when altitude specified, or FLR specified.
15.1.2 "Location:where-relation-switch"
Location:where-relation-switches allow a LESS script to make call
decisions based on the location relation of two persons. They are
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summarized in Figure 29.
Node: "Location:where-relation-switch"
Outputs: "where-relation" Specific location relation to match
Parameters: "uri1" the first location occupier's uri
"uri2" the second location occupier's uri
Output: "where-relation"
Parameters: "distance" Distance value between two persons.
"condition" Valid only if distance presented.
Value is (in|out|at|).
Default value is "at".
"unit" Valid only if distance presented.
Value is (m|km|mi|in|ft|yd
|naut mi). Default value is "m".
"direction" Direction relation between two
persons, value is "(south|north|
west|east|above|below)".
"same" A space separated list containing
location attributes, e.g., LOC, that
two persons have the same value.
"difference" A space separated list containing
location attributes, that two
persons have different values.
Figure 29: Syntax of the "Location:where-relation-switch" node
Location:where-relation-switches have two node parameters: The
mandatory parameter "uri1" specifies the first location occupier's
uri. The optional parameter "uri2" specifies the second location
occupier's uri. If not provided, the second location occupier will be
the script owner.
The "where-relation" output tag may have one or more parameters,
indicating the exact relation to match.
The "distance" parameter indicates the distance between two persons.
The "condition" and "unit" parameters are used for distance
measuring. They have the same meanings as those defined in "where-
switch".
The "direction" parameter indicates relative positions between two
persons. For example, "south" means uri1 is south of uri2.
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The "same" and "difference" indicating the relationship between two
persons' location attributes. The attributes can be geospatial
location attributes, such as "longitude", "latitude", and "altitude".
They can also be civil location attributes, such as country, "A1",
"A2", "A3", "A4", "A5", "A6", "PRD", "POD", "STS", "HNO", "HNS",
"LMK", "LOC", "FLR", "NAM", and "PC".
15.2 IANA Considerations
This extension registers a new URN per RFC 2141 [6], RFC 2648 [7],
and RFC 3688 [8].
The XML namespace urn:ietf:params:xml:ns:less:location will only
refer to the version of LESS mid-call handling extension in this
document and will not change. Any other LESS enhancements MUST be
made by extensions and MUST have different namespaces.
15.2.1 URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:less:location
URI: urn:ietf:params:xml:ns:less:location
Registrant Contact: Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Location-based Service Extension of the Language for End System Services Namespace</title>
</head>
<body>
<h1>Namespace for the Location-based Service Extension of the Language for End System Services</h1>
<h2>urn:ietf:params:xml:ns:less:location</h2>
<p><a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
15.2.2 Schema registration
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This specification registers XML Schema for LESS, as per the
guidelines in [8].
URI: urn:ietf:params:xml:schema:less:location
Registrant contact:
Xiaotao Wu <xiaotaow@cs.columbia.edu>
Henning Schulzrinne <hgs@cs.columbia.edu>
XML: The XML can be found in Section 19.2.
15.2.3 MIME Registration
LESS Media extension has the same MIME type as LESS as defined in
Section 8.3.
16 Queue handling extension
Many call center services require queueing incoming calls for
available operators. This extension defines two actions for queue
operation.
16.1 Actions
16.1.1 "Queue:enqueue" Action
"Queue:enqueue" actions cause the user agent to put an incoming call
in a waiting queue. Their syntax is shown in Figure 30.
Node: "Queue:enqueue"
Outputs: "full" If the number of calls exceeds the "maxlen".
Parameters: "queue" The name of the queue. Possible values can be
any string. Two pre-defined names are "hold"
and "callback", which hosts holding calls and
calls waiting for callback, accordingly.
If not provided, use user agent's default queue.
"maxlen" The maximum calls can be held in the queue.
Output: "full"
Parameters: none
Figure 30: Syntax of the "Queue:enqueue" node
16.1.2 "Queue:dequeue" Action
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"Queue:dequeue" actions cause the user agent to retrieve a call from
a waiting queue. Their syntax is shown in Figure 31.
Node: "Queue:dequeue"
Outputs: "success" A call get retrieved.
"failure" Queue empty or other reasons. "dequeue" failed.
Parameters: "queue" The name of the queue. Possible values can be
any string. Two pre-defined names are "hold"
and "callback", which hosts holding calls and
calls waiting for callback, accordingly.
If not provided, use user agent's default queue.
Output: "success"
Parameters: none
Output: "failure"
Parameters: none
Figure 31: Syntax of the "Queue:dequeue" node
17 Examples
The following sections investigate services suitable for end systems.
We looked into ITU Q.1211 [16] services, AT&T 5ESS switch services
[17], services defined in CSTA Phase III [18], and new services
incorporated with other Internet services, such as email and presence
information, for appropriate end system services.
17.1 Q.1211 services
The technical report by Lennox et al [19] illustrated how to use SIP
to handle Q.1211 services. In table 1 of that report, it defines
what Q.1211 services are suitable for end systems. We only focuses on
the services appropriate for end systems and tries to use LESS to
program those services.
17.1.1 Abbreviated dialing (ABD)
"Abbreviated dialing allows the definition of short (e.g., two digit)
digit sequences to represent the actual dialing digit sequence for a
public or private numbering scheme."
Internet telephony end systems may simply use speed-dial buttons to
handle the work. Instead of dialing a digit sequence, a single
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button-click may trigger a call. End systems may also use LESS
service scripts to do the translation from a short sequence to an
actual sequence. Below is a LESS script example for the ABD service.
<less>
<UI:command command="call">
<address-switch field="destination">
<address is="tel:11; phone-context=local">
<location url="tel:+1-212-939-7054">
<call/>
</location>
</address>
</address-switch>
</UI:command>
</less>
17.1.2 Attendant (ATT)
"This allows VPN users to access an attendant (operator) position
within the VPN for providing VPN service information (e.g., VPN
numbers) by dialing a special access code. An Internet telephony end
system needs only to be configured with an address of an appropriate
local operator to translate the special access code to the actual
local address of an attendant, or some address which will resolve to
that address." For LESS, this is similar to the ABD service (Section
17.1.1) handling.
17.1.3 Authentication (AUTC)
"This allows verification that a user is allowed to access certain
options in the telephone network. This should be in basic end system
implementation."
<less>
<UI:command command="call">
<authenticate user="{message.origin}" target="local">
<success>
<!-- If authentication succeeded, accept the call -->
<call/>
</success>
<failure>
<!-- If authentication failed, terminate the call attempt-->
<terminate/>
</failure>
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</authenticate>
</UI:command>
</less>
17.1.4 Authorization code (AUTZ)
"This allows a user (typically in a VPN) to override the restrictions
placed on the system from which calls are made. This should be in
basic end system implementation." Though we can user LESS scripts to
automate the authorization process, it is unsafe to save the codes in
LESS scripts.
17.1.5 Automatic call back (ACB)
"This feature allows the called party to automatically call back the
calling party of the last call directed to the called party."
This can be handled by either end systems or network servers. If
handled by a network server, the network server should send a SIP
REFER request to the calling party to initiate the call back (This is
more like traditional Automatic Callback service).
The service involves two steps, one is to log received invitations,
the other is to retrieve the invitations and make calls. Below is a
LESS service script handling this service.
<less>
<incoming>
<status-switch status-name="activity">
<status is="busy">
<reject>
<!-- Any action should have a 'next' for subsequent actions -->
<!-- If one action has a sibling action, the sibling action
will be executed in parallel with this action -->
<next>
<!-- A "callback" queue is defined -->
<Queue:enqueue queue="callback"/>
</next>
</reject>
</status>
</status-switch>
</incoming>
<Event:notification>
<address-switch field="origin">
<address url="{agent.uri}">
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<Event:event-switch>
<Event:event package="presence" status="open" activity="">
<!-- If no 'number' parameter provided, the Queue:dequeue action
will sequentially retrieve all elements in the queue -->
<Queue:dequeue queue="callback">
<success>
<call/>
</success>
</Queue:dequeue>
</Event:event>
</Event:event-switch>
</address>
</address-switch>
</Event:notification>
</less>
17.1.6 Call distribution (CD)
"This service feature allows the served user to specify the
percentage of calls to be distributed among two or more destinations.
Other criteria may also apply to the distribution of calls to each
destination."
This is usually done by network servers. If we extend CPL with a
switch checking multiple destinations' status, we can handle the
service in a proxy server by using CPL.
17.1.7 Call forwarding (CF)
"This service feature allows a user to have his incoming calls
addressed to another number, no matter what the called party line
status may be." A simple LESS script can handle this below:
<less>
<incoming>
<location url="sip:bob-home@example.com">
<redirect/>
</location>
</incoming>
</less>
17.1.8 Call forwarding on busy/don't answer (CFC)
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"This service feature allows the called user to forward particular
calls if the called user is busy or does not answer within a
specified number of rings."
This service requires an end system to check its status and make call
decisions. The following script forwards calls on busy.
<less>
<incoming>
<status-switch status-name="activity">
<status is="on-the-phone">
<location url="sip:bob-home@example.com">
<redirect/>
</location>
</status>
</status-switch>
</incoming>
</less>
The following script is for call forwarding on no answer.
<less>
<incoming>
<alert timeout="2000">
<timeout>
<location url="sip:bob-home@example.com">
<redirect/>
</location>
</timeout>
</alert>
</incoming>
</less>
17.1.9 Call gapping (GAP)
"This feature allows the service provider to restrict the number of
calls to a served user to prevent congestion of the network." This
service should be implemented in network servers. A similar feature,
Call Limiter (LIM) (Section 17.1.11), will do the similar thing but
for end systems.
17.1.10 Call hold with announcement (CHA)
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"The call hold with announcement service feature allows a subscriber
to place a call on hold with options to play music or customized
announcements to the held party." This service requires user
interaction. A LESS script that can enhance the service by
customizing the announcements based on addresses is shown below:
<less>
<!-- A trigger to handle user input -->
<!-- For portability, the values for the parameter 'command'
are pre-defined, each command can only be applied under a
certain condition. 'hold' can only be used with an
ongoing call -->
<UI:command command="hold">
<address-switch field="destination">
<address is="sip:bob@example.com">
<Media:media media="audio" input="music.au" mode="sendonly">
<Media:mediaupdate/>
</Media:media>
</address>
</address-switch>
</UI:command>
</less>
17.1.11 Call limiter (LIM)
"This service feature allows a served user to specify the maximum
number of simultaneous calls to a served user's destination. If the
destination is busy, the call may be routed to an alternative
destination."
Internet telephony end systems can have virtually unlimited lines.
However, the resources (CPU, memory, I/O devices) are limited for an
end device so the number of simultaneous calls is limited. This can
be handled by a LESS script below:
<less>
<incoming>
<status-switch status-name="active-calls">
<status equal="2">
<reject status="busy"/>
</status>
</status-switch>
</incoming>
</less>
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17.1.12 Call logging (LOG)
"This service feature allows for a record to be prepared each time
that a call is received to a specified telephone number." The <log>
action in LESS can handle this feature.
<less>
<incoming>
<log/>
</incoming>
</less>
17.1.13 Call queueing (QUE)
"This service feature allows calls which would otherwise be declared
busy to be placed in a queue and connected as soon as the free
condition is detected. Upon entering the queue, the caller hears an
initial announcement informing the caller the call will be answered
when a line is available."
The call queueing service can be handled by an application server in
the network. End systems can also handle it. The LESS script below
handles the service.
<less>
<incoming>
<status-switch status-name="active-calls">
<!-- For more than one active call, we use 'active-calls="1+" -->
<status equal="1">
<Media:media media="audio" input="music.au" mode="sendonly">
<accept>
<next>
<Queue:enqueue queue="hold"/>
</next>
</accept>
</Media:media>
</status>
</status-switch>
</incoming>
<Event:notification>
<status-switch status-name="active-calls">
<status equal="0">
<!-- Retrieve only one call from the hold queue -->
<Queue:dequeue queue="hold" number="1">
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<success>
<Media:media media="audio" input="microphone" mode="sendrecv">
<Media:mediaupdate/>
</Media:media>
</success>
</Queue:dequeue>
</status>
</status-switch>
</Event:notification>
</less>
17.1.14 Call transfer (TRA)
"The call transfer service feature allows a subscriber to place a
call on hold and transfer the call to another location."
In LESS, the <transfer> action is used to handle the service. Call
transfer is a user triggered service. A LESS script can be triggered
by a user input event to perform a transfer.
<less>
<!-- the 'transfer' command only applies to the current ongoing call -->
<UI:command command="transfer">
<!-- Transfer all calls between 09:00 ~ 17:00 to specialist@foo.com,
otherwise, to technician@foo.com -->
<time-switch>
<time dtstart="20040716T090000Z"
duration="PT8H" freq="weekly" byday="MO,TU,WE,TH,FR">
<location uri="specialist@foo.com">
<transfer/>
</location>
</time>
<otherwise>
<location uri="technician@foo.com">
<transfer/>
</location>
</otherwise>
</time-switch>
</UI:command>
</less>
17.1.15 Call waiting (CW)
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"This service feature allows a subscriber to receive a notification
that another party is trying to reach his number while he is busy
talking to another calling party."
Since an Internet telephony end system can have multiple lines and a
better user interface, such as a bigger LCD display, it can alert
users for any new calls. No service scripts required for this
service.
17.1.16 Closed user group (CUG)
"This service feature allows the user to be a member of a set of
users who are normally authorized to make and receive calls only
within the group."
This service should be put on network servers, though end systems can
handle it by using call screening services. We will introduce call
screening services in Section 17.1.30 and 17.1.37.
17.1.17 Consultation calling (COC)
"The consultation calling service feature allows a subscriber to
place a call on hold, in order to initiate a new call for
consultation."
For Internet telephony end systems, this service is similar to Call
hold with announcements (CHA), which we have discussed in Section
17.1.10.
17.1.18 Customer profile management (CPM)
"This service feature allows the subscriber to real-time manage his
service profile, i.e. terminating destinations, announcements to be
played, call distribution, and so on."
This is about service script management. There should be a friendly
service creation and management user interface for end systems.
17.1.19 Customer recorded announcement (CRA)
"This service allows a call to be completed to a (customized)
terminating announcement instead of a subscriber line. The served
user may define different announcements for unsuccessful call
completions due to different reasons (e.g. caller outside business
hours, all lines are busy)." The switches in LESS can do the
customization work. For example, a time-based customization is as
below:
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<less>
<incoming>
<!-- Effective from 07/16/2004, if an incoming call is after
05:00:00 PM Friday, and before 09:00:00 AM Monday, play
the no_office_hour.au announcement -->
<time-switch>
<time dtstart="20040716T170000Z"
duration="PT16H" freq="weekly" byday="MO,TU,WE,TH,FR">
<Media:media media="audio" source="no_office_hour.au" mode="sendonly">
<accept/>
</Media:media>
</time>
</time-switch>
</incoming>
</less>
17.1.20 Customized ringing (CRG)
"This service feature allows the subscriber to allocate a distinctive
ringing to a list of calling parties."
This service can only be handled in an end system. The script below
shows an enhanced version not only based on address but also based on
priority of the call to perform customized ringing.
<less>
<incoming>
<priority-switch>
<priority equal="emergency">
<alert priority="emergency"/>
</priority>
<otherwise>
<address-switch field="origin">
<address is="sip:bob@example.com">
<alert audio="bob.au"/>
</address>
<otherwise>
<alert/>
</otherwise>
</address-switch>
</otherwise>
</priority-switch>
</incoming>
</less>
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17.1.21 Destination user prompter (DUP)
"This service feature enables to prompt the called party with a
specific announcement. Such an announcement may ask the called party
enter an extra numbering, e.g. through DTMF, or a voice instruction
that can be used by the service logic to continue to process the
call."
Though we can use LESS <Media:media> modifier to easily
play an announcement, it is out of LESS's scope to handle
DTMF inputs. The DTMF handling falls into VoiceXML's [20]
domain. For example, UI:prompt script="input1.vxml"/>.
More investigation is required on integrating VoiceXML into
LESS.
17.1.22 Follow-me diversion (FMD)
"With this service feature, a user may register for incoming calls to
any terminal access." This service should be in network servers.
17.1.23 Mass calling (MAS)
"This service feature allows processing of huge numbers of incoming
calls, generated by broadcasted advertisings or games." This service
should be handled by network servers.
17.1.24 Meet-me conference (MMC)
"This service feature allows the user to reserve a conference
resource for making a multi-party call. At a specified date and time,
each participant in the conference has to dial a designated number in
order to have access to the conference." This is a standard
conferencing service. We can use LESS to perform time and caller
checking, and authentication.
<less>
<incoming>
<time-switch>
<!-- a conference on every Monday from 17:00 to 19:00 -->
<time dtstart="20040716T170000Z"
duration="PT2H" freq="weekly" byday="MO">
<address-switch field="origin">
<address is="sip:bob@example.com">
<authenticate user="{message.destination}" target="remote">
<success>
<accept/>
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</success>
</authenticate>
</address>
</address-switch>
</time>
</incoming>
</less>
17.1.25 Multi-way calling (MWC)
"This service feature allows the user to establish multiple,
simultaneous telephone calls with other parties."
An Internet telephony end system can initiate as many simultaneous
calls as it wishes as long as the network bandwidth and the CPU
processing speed permit. A changed version of the service will be to
put a limit on the number of simultaneous calls. The changed version
can be handled by a LESS script below:
<less>
<UI:command command="call">
<status-switch status-name="active-calls">
<status equal="2">
<terminate>
<next>
<alert message="Only 2 active calls allowed"/>
</next>
</terminate>
</status>
</status-switch>
</UI:command>
</less>
17.1.26 Off-net access (OFA)
"This service feature allows a VPN user to access his or her VPN from
any non-VPN station in the PSTN by using a personal identification
number (PIN)." This service should not be handled by using LESS
scripts.
17.1.27 Off-net calling (ONC)
"This service feature allows the user to call outside the VPN
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network."
This service is just a standard firewall traversal process, no
service scripts required.
17.1.28 One number (ONE)
"This feature allows a subscriber with two or more terminating lines
in any number of locations to have a single telephone number. This
allows businesses to advertise just one telephone number throughout
their market area and to maintain their operations in different
locations to maximize efficiency. The subscriber can specify which
calls are to be terminated on which terminating lines based on the
area the calls originate."
This is a standard SIP proxy service, not handled by end systems.
17.1.29 Origin dependent routing (ODR)
"This service feature enables the subscriber to accept or reject a
call, and in case of acceptance, to route this call, according to the
calling party geographical location. This service feature allows the
served user to specify the destination installations according to the
geographical area from which the call was originated."
This service requires <Location:where-switch> to handle location-
based call routing. A service script below can handle the service.
For end systems, we use <redirect/> action to route calls. A proxy
server is a more appropriate place to host the service, and use
<proxy/> action to route calls.
<less>
<incoming>
<address-switch field="origin">
<address is="sip:bob@example.com">
<Location:where-switch type="civil" principle="sip:bob@example.com">
<Location:where country="USA" A1="New York"
A3="New York" A6="West 120th" HNO="450" LOC="Room 563">
<location url="sip:bob-office@example.com">
<redirect/>
</location>
</Location:where>
<otherwise>
<location url="sip:bob-mobile@example.com">
<redirect/>
</location>
</otherwise>
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</Location:where-switch>
</address>
</address-switch>
</incoming>
</less>
17.1.30 Originating call screening (OCS)
"This service feature allows the served user to bar calls from
certain areas based on the District code of the area from which the
call is originated." This service can be handled by using address-
switch.
<less>
<incoming>
<address-switch field="destination" subfield="host">
<address is="example.com">
<reject status="reject"/>
</address>
</address-switch>
</incoming>
</less>
17.1.31 Originating user prompter (OUP)
"This service feature allows a served user to provide an announcement
which will request the caller to enter a digit or series of digits
via a DTMF phone or generator. The collected digits will provide
additional information that can be used for direct routing or as a
security check during call processing."
This service can be in a network server or a user agent. To enable a
user agent to support this service, it requires the user agent to
handle the interaction with remote users.
17.1.32 Personal numbering (PN)
"This service feature supports a UPT number that uniquely identifies
each UPT user and is used by the caller to reach that UPT user."
Reaching a user through a personal address is accomplished simply by
a proxy or redirection server which locates the user.
17.1.33 Premium charging (PRMC)
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"This service feature allows for the pay back of part of the cost of
a call to the called party." This service is out of the scope of
LESS.
17.1.34 Private numbering plan (PNP)
"This service feature allows the subscriber to maintain a numbering
plan within his private network, which is separate from the public
numbering plan." This service should usually be put in outbound
proxy servers. If we provide such service in end systems, it would be
similar to the Abbreviated dialing (ABD) service we introduced in
Section 17.1.1.
17.1.35 Reverse charging (REVC)
"This service feature allows the service subscriber (e.g. freephone)
to accept to receive calls at its expense and be charged for the
entire cost of the call."
This service and the next service "Split charging" require a detailed
VoIP charging schema and have the charging information available to
users. Currently, LESS cannot handle this kind of service. However,
if call signaling messages can provide charging information, LESS
scripts can perform call decisions, such as automatically rejecting a
reverse charging calls unless it is from certain users, based on the
charging information.
17.1.36 Split charging (SPLC)
"This service feature allows for the separation of charges for a
specific call, the calling and called party each being charged for
one part of the call." This service is similar to the previous
service, LESS cannot handle the service.
17.1.37 Terminating call screening (TCS)
"This service feature allows the user to screen calls based on the
terminating telephone number dialed." Below is a LESS script example
handling this service.
<less>
<incoming>
<address-switch field="destination" subfield="host">
<address is="example.com">
<reject status="reject"/>
</address>
</address-switch>
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</incoming>
</less>
17.1.38 Time dependent routing (TDR)
"This services feature allows the served user to apply different call
treatments based on the time of day, day of week, day of year,
holiday, etc." Usually, routing services should be put in network
servers, but we can perform similar services for time dependent
redirecting. This can be handled by LESS time-switch.
<less>
<incoming>
<time-switch>
<time dtstart="20040716T170000Z"
duration="PT8H" freq="weekly" byday="MO">
<location url="sip:bob@voicemail.com>
<redirect/>
</location>
</time>
</time-switch>
</incoming>
</less>
17.2 5ESS services
In this section, we investigate the services introduced in "AT&T 5ESS
Switch The Premier Solution, Feature Handbook" [17]. 5ESS services
including the following categories: BRCS (Business and Residence
Custom Services) features, ISDN features (message and MBKS), Public
Service features (emergency), Defense Switched Network Features, Toll
and Tandem features, Interoffice Signaling and Control features,
Operator Service Position System features, OA&M features. Among these
categories, we are most interested in the BRCS features because many
of BRCS features can be handled in end systems. For ISDN features, we
will discuss the Message Services and the MBKS (Multibutton Key
Telephone System). For Public Service features, we will discuss the
group alerting service. We will not discuss the other service
categories. We only list the services suitable for end systems.
17.2.1 Attendant call transfer (also known as Call splitting)
"The service allows the attendant to flash and dial a code before
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dialing the third leg of a 3-way call. This inhibits the automatic
connecting of all the parties to allow private consultation between
the attendant and the third leg of the call. If the code is not
dialed, the automatic 3-way is formed."
Since an Internet telephony end system usually can have multiple
lines, it is easy to put one line on hold and initiate another call.
However, to enable this service, an end system should be able to
merge an active call and a held call into a 3-way call.
This service is not a programmable service, a user will manually use
a second line to initiate the second call, and manually instruct his
user agent to merge two calls.
17.2.2 Attendant camp-on
"This service allows incoming calls that the attendant attempts to
complete to a busy station to be held waiting until the busy station
becomes idle. The busy station receives a tone (indication of camp-
on) each time the attendant attempts a completion. The call being
transferred receives audible ringing, special tone followed by
audible ringing, or optional silence, while waiting for the busy
station to answer the call." The following script can handle the
service.
<less>
<incoming>
<status-switch status-name="active-calls">
<!-- We use 1+ to represent 1 or more active-calls -->
<status greater="1">
<Media:media source="wait.au" mode="sendonly">
<accept>
<next>
<Queue:enqueue queue="hold"/>
</next>
</accept>
</Media:media>
</status>
</status-switch>
</incoming>
<Event:notification>
<status-switch status-name="active-calls">
<status is="0">
<Queue:dequeue queue="hold" number="1">
<success>
<Media:media media="audio" input="microphone" mode="sendrecv">
<Media:mediaupdate/>
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</Media:media>
</success>
</Queue:dequeue>
</status>
</status-switch>
</Event:notification>
</less>
17.2.3 Attendant conference
"This service enables an attendant to initiate a conference call
involving up to six parties (including attendant). The selection of a
special conference attendant can be done from any station within the
same customer group by dialing a particular access code."
There are two ways to handle conferencing services in an end system,
one is to have all conference participants to connect to a conference
server (by REFER or third-party call control), the other is to use
end system mixing. The first way is more scalable, but requires an
external conference server. The second way requires an end system
supporting mixing. The following scripts show both ways for a time-
based conference initiation.
<less>
<!-- Use SIP REFER -->
<timer dtstart="20040716T170000Z"
duration="PT2H" freq="weekly" byday="MO">
<lookup source="sip:bob@example.com
sip:tom@example.com sip:alice@abc.com">
<success>
<call>
<success>
<location url="sip:conf@example.com">
<transfer/>
</location>
</success>
</call>
</success>
</lookup>
</timer>
</less>
The script will automatically send a call invitation to each URL in
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the list, once a call established, the script will transfer the call
to the conference server at sip:conf@example.com.
<less>
<!-- Use local mixing -->
<timer dtstart="20040716T170000Z"
duration="PT2H" freq="weekly" byday="MO">
<sub ref="IRTdef"/>
<lookup source="sip:bob@ex.com sip:tom@ex.com">
<success>
<call subject="Group meeting">
<success>
<merge subject="Group meeting"/>
</success>
</call>
</success>
</lookup>
</timer>
</less>
17.2.4 Authorization code
"The codes allow the station user to input an assigned code to change
the restrictions associated with the originating station to those
associated with the assigned authorization code. Thus, unauthorized
use of facilities is avoid."
<less>
<UI:command command="call">
<address-switch field="destination">
<address is="sip:conf123@example.com">
<call>
<success>
<IM:sendmsg type="dtmf" digits="123456"/>
</success>
</call>
</address>
</address-switch>
</UI:command>
</less>
17.2.5 Automatic recall
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"This service lets the customer automatically call the LOCDN (last
outgoing call directory number) currently associated with the
customer's station when both stations become idle. It is different
from Automaticall Callback, which automatically places a call on
LICDN (last incoming call directory number)." The service script
below shows how to program the service in LESS.
<less>
<UI:command command="call">
<call>
<failed status="486,603">
<Queue:enqueue queue="callback">
<next>
<Event:subscribe/>
</next>
</Queue:enqueue>
</failed>
</call>
</UI:command>
<Event:notification>
<Event:event-switch>
<Event:event activity="normal">
<!-- User {message.origin} to represent the sender of the notification-->
<Queue:dequeue queue="callback" match="{message.origin}">
<success>
<call/>
</success>
</Queue:dequeue>
</Event:event>
</Event:event-switch>
</Event:notification>
</less>
17.2.6 Call forwarding busy line (CFBL)
"This service permits calls attempting to terminate to a busy line to
be redirected to another customer-specified line." The following
script can handle the service.
<less>
<incoming>
<status-switch status-name="active-calls">
<status greater="1">
<location url="sip:phone2@example.com">
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<redirect/>
</location>
</status>
</status-switch>
</incoming>
</less>
17.2.7 Call forwarding busy line--incoming only
"This service provides that only incoming DID calls are forwarded to
the specified business group line on busy. Intragroup call attempts
and attempts from private facilities to terminate to the busy line
receive busy treatment." This is in fact address-based call
forwarding services.
<less>
<incoming>
<status-switch status-name="active-calls">
<status greater="1">
<address-switch field="origin">
<address isnot="sip:*@example.com">
<location url="sip:phone2@example.com">
<redirect/>
</location>
</address>
</address-switch>
</status>
</status-switch>
</incoming>
</less>
17.2.8 Call forwarding--don't answer
"This service forwards incoming calls to a station when the called
station is not answered after a customer-specified number of ringing
cycles." The script below can handle the service.
<less>
<incoming>
<alert timeout="2000">
<timeout>
<location url="sip:phone2@example.com">
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<redirect/>
</location>
</timeout>
</alert>
</incoming>
</less>
17.2.9 Unconditional call forwarding
"This service forwards all incoming calls to another telephone." We
can simply handle the service by using <redirect/> action.
<less>
<incoming>
<location url="sip:bob@room123.example.com">
<redirect/>
</location>
</incoming>
</less>
17.2.10 Call hold
"This service allows a station user to 'hold' a call in progress by
flashing and then dialing the call hold code. This frees the line for
originating another call, answering a waiting call, or returning to a
held call." In LESS, we use the action <Media:mediaupdate/> to
change the media source for "hold" and "unhold" service.
...
<!-- hold -->
<Media:media media="audio" input="music.au" mode="sendonly">
<Media:mediaupdate/>
</Media:media>
...
<!-- unhold -->
<Media:media media="audio" input="microphone" mode="sendrecv">
<Media:mediaupdate/>
</Media:media>
17.2.11 Call transfer--individual--all calls
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"This service allows a station user to transfer any established call
to another station within or outside the PBX or business group
without the assistance of the attendant. This is accomplished by
flashing while on a stable 2-party call, dialing the desired party,
and hanging up the telephone." The <transfer/> action can handle
this service.
<less>
<incoming>
<media media="audio" input="transfer.au" mode="sendonly">
<accept>
<next>
<location url="sip:bob@room123.example.com">
<transfer>
<failed>
<media media="audio" input="failed.au" mode="sendonly">
<mediaupdate/>
</media>
</failed>
</transfer>
</location>
</next>
</accept>
</media>
</incoming>
</less>
17.2.12 Call waiting and cancel call waiting
Since an Internet telephony end system usually have multiple lines,
users do not have to use flash button to switch calls. However, users
should be able to control how many active calls an end device can
handle. The following script can help to configure the maximum
number of calls.
<less>
<incoming>
<status-switch status-name="active-calls">
<status greater="3">
<reject reason="busy"/>
</status>
</status-switch>
</incoming>
</less>
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17.2.13 Circle hunting
"This service allows all lines in a multiline hunt group to be tested
for busy, regardless of the point of entry into the group. When a
call is made to a line in an MLHG, a regular hunt is performed
starting at the terminal associated with the dialed number. It
continues to the last terminal in the MLHG, then proceeds to the
first terminal in the group and continues to hunt sequentially
through the remaining lines in the group. Busy tone is returnedif the
called terminal is reached without finding one that is idle." This
service is more suitable for a proxy server to handle. However, we
can also handle it in an end system by using <transfer/> action.
<less>
<incoming>
<media type="audio" input="wait.au" mode="sendonly">
<accept>
<next>
<lookup source="sip:bob@ex.com sip:tom@ex.com"
order="sequential">
<success>
<transfer>
<succeed>
<stop/>
</succeed>
</transfer>
</success>
</lookup>
</next>
</accept>
</media>
</incoming>
</less>
17.2.14 Conference calling
"The service allows a station user to establish a conference call
involving up to five other parties without attendant assistance."
This service is almost the same as the attendant conferencing service
we discussed before, it requires an end system to support mixing, and
to merge an incoming call to an existing conference call. We use
<merge/> action to handle the merge.
17.2.15 Customer-changeable speed calling
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"This service allows subscribers to assign their own Speed Calling
codes directly and immediately from their own telephone by dialing a
change Speed Calling list access code, an abbreviated code and a new
telephone number. It is available for 1- and or 2-digit Speed Calling
list owners." In an end system, speed dialing modification should be
done by editing service scripts from a local GUI. Below is a script
for speed dialing handling.
<less>
<UI:command command="call">
<address-switch field="destination" subfield="user">
<address is="1">
<location url="sip:bob@example.com">
<call/>
</location>
</address>
</address-switch>
</UI:command>
</less>
17.2.16 Direct connect
"This service automatically places a call to a preselected called
number when a station goes off-hook. This feature can be used for
introffice and interoffice calls and does not affect termination to a
line." This service requires a specially configured UA. The service
should not be handled by a service script.
17.2.17 Distinctive ringing
This service applies a distinctive ringing to determine the source of
an incoming call. The following script handles the service.
<less>
<incoming>
<address-switch field="origin">
<address is="sip:bob@example.com">
<alert audio="bob.au"/>
</address>
</address-switch>
</incoming>
</less>
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17.2.18 Four- and eight-party
"This service provides POTS for up to four or eight customers sharing
the same line. It provides fully selective ringing or semiselective
ringing for up to four customers and semiselective ringing for five
to eight customers." The following script plays distinctive ringing
for different user sharing the same phone.
<less>
<incoming>
<address-switch field="destination">
<address is="sip:bob@example.com">
<alert audio="bob.au"/>
</address>
<otherwise>
<address-switch field="destination">
<address is="sip:tom@example.com">
<alert audio="tom.au"/>
</address>
<otherwise>
<address-switch field="destination">
<address is="sip:mary@example.com">
<alert audio="mary.au"/>
</address>
</address-switch>
</otherwise>
</address-switch>
</otherwise>
</address-switch>
</incoming>
</less>
17.2.19 Recorded telephone dictation
"This service permits access to and control of customer-owned
dictating equipment from a station in the customer group." This
service requires an end system to be able to record and playback a
phone call.
<less>
<UI:command command="accept">
<address-switch field="origin">
<address is="sip:bob@example.com">
<log record="true"/>
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</address>
</address-switch>
</UI:command>
</less>
17.2.20 Time-of-Day features
"This kind of features can perform automatic actions based on time-
of-day. For example, Slumber Service (also known as Do Not Disturb)
can temporarily prohibit an individual customer station or a
functional group of individual stations from receiving calls. It is
used in hospitals to restrict incoming calls to patients during the
night or any designated period." We can use LESS time-switch to
handle the service.
<less>
<incoming>
<time-switch>
<time dtstart="20040716T230000Z"
duration="PT8H" freq="daily">
<reject reason="Do not disturb"/>
</time>
</time-switch>
</incoming>
</less>
17.2.21 Message services
ISDN Message Services provides centralized and personalized call
coverage of message answering capabilities. For Basic Message
Service, calls to a message service client are redirected via one of
the following features.
Call forward -- busy line
Call forward -- don't answer
Call forward -- variable
To provide the personalized call coverage, message service
attendants can be equipped with special ISDN station sets that
display call information on calls directed to the message
service center. The following information is available for
display: Call type, Originating party DN, Calling party DN. This
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service requires an end system can identify a message service,
e.g., a voicemail server. The following script forward a call to
a voicemail server when the user is busy.
<less>
<incoming>
<status-switch status-name="active-calls">
<status greater="2">
<location url="sip:bob@voicemail.example.com">
<redirect/>
</location>
</status>
</status-switch>
</incoming>
</less>
There can be additional features for message services, for example,
message waiting indicator, which can inform a client that he/she has
message(s) waiting. The Message Waiting Indication Event Package for
SIP [21] can provide required message information. An end system
should be able to handle the event for the message waiting indicator
service.
<less>
<Event:notification>
<Event:event-switch>
<Event:event package="message-summary" message-waiting="yes">
<alert message="There are new messages for you" audio="mwi.au"/>
</Event:event>
</Event:event-switch>
</Event:notification>
</less>
17.2.22 Multibutton key telephone system (MBKS)
"Feature Function Buttons on the MBKS set can be assigned to activate
certain features. For example, a user can press the function button
assigned to Automatic Callback on Busy when a busy number is dialed."
We can bind a script to a specific button for this kind of services.
17.2.23 Group alerting
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"This service permits the controller (or alerting party), upon
dialing a code, to signal a preselected number of telephones
simultaneously. One-way communication is established from the
controller to all members of the group that responded to the signal."
The script below can handle the service.
<less>
<UI:command command="call">
<!-- define name="Alerting group"
values="sip:security@abc.com sip:fire@abc.com" -->
<address-switch field="destination">
<address is="sip:alert@example.com">
<lookup source="sip:security@abc.com sip:fire@abc.com">
<media mode="sendonly">
<call subject="Alert">
<success>
<merge subject="Alert"/>
</success>
</call>
</media>
</lookup>
</address>
</address-switch>
</UI:command>
</less>
17.3 Services defined in CSTA Phase III
In this section, we investigate the services in ECMA standard ECMA-
269, "Services for Computer Supported Telecommunications Applications
(CSTA) Phase III" [18]. The call model of CSTA services is to use
protocol messages to control end systems. Many CSTA services are in
fact simply actions in LESS. For example, Accept Call is a CSTA
control service, but just an action, <accept/>, in LESS.
CSTA Phase III categorizes services into System Services, Monitoring
Services, Snapshot Services, Call Control Services and Events, Call
Associated Features, Media Attachment Services and Events, Routing
Services, Physical Device Features, Logical Device Features, Device
Maintenance Events, I/O Services, Data Collection Services, Voice
Services and Events, and Call Detail Record (CDR) Services. Among
these services, System Services are used to handle the relationship
between switch functions and CSTA service functions and are out of
the scope of LESS, Monitoring Services are like to define the DPs
(Detection Points) in Intelligent Network (IN) and are also out of
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the scope of LESS. Snapshot Services are used to send device
information to switch functions, not suitable for LESS. The Routing
Services are not end system services and are also not suitable for
LESS. The Device Maintenance Events, I/O Services, and Data
Collection Services are too low-level for end user oriented service
programming, thus they are not suitable for LESS. We will discuss the
other services below.
17.3.1 Accept call
This service can be mapped to <alert/> action in LESS.
17.3.2 Alternate call
This service places an existing active call on hold and then retrieve
a previously held call. This service in fact involves several
actions. We can use the <Media:mediaupdate/> action to put a call
held/unheld and put held calls into a queue by enqueue action.
17.3.3 Answer call
This service can be mapped to <accept/> action in LESS.
17.3.4 Call back call-related
The Call Back Call-Related service allows a computing function to
request that the calling device retry the call to the called device
when the called device is in an appropriate state to accept the call.
This is the same as the ACB service described in Section 17.2.5.
17.3.5 Call back message call-related
The Call Back Message Call-Related service allows a computing
function to request that the switching function leave a pre-defined
message requesting that the called device call the calling device.
For example, the called device may have been busy when called.
<less>
<incoming>
<status-switch status-name="activity">
<status is="on-the-phone">
<alert message="Please call back {message.origin}">
<next>
<Queue:enqueue queue="callback"/>
</next>
</alert>
</status>
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</status-switch>
</incoming>
</less>
17.3.6 Camp on call
The Camp On Call service allows the computing function to queue a
call for a device (that typically is busy) until that device becomes
available. The script below can handle the service.
<less>
<incoming>
<status-switch status-name="active-name">
<status greater="1">
<media type="audio" input="wait.au" mode="sendonly">
<accept>
<next>
<Queue:enqueue queue="callback"/>
</next>
</accept>
</media>
</status>
</status-switch>
</incoming>
</less>
17.3.7 Clear call
The Clear Call service releases all devices from an existing call.
In the case of a conference call, this results in all devices in the
conference call being released from the call. This service can be
mapped to the <terminate/> action.
17.3.8 Clear connection
The Clear Connection service releases a specific device from a call.
In the case of a two-party call, this may result in the call being
torn down. In the case of a conference call, this results in the
specific party being removed from the conference. For a two-party
call, it is the same as Clear Call and can be represented by the
<terminate/> action. For a conference call, we need to provide a
parameter to the <terminate/> action to indicate which call leg
should be disconnected. We can use a SIP url to identify the call
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leg.
17.3.9 Conference call
The Conference Call service provides a conference of an existing held
call and another active call at a conferencing device. This is the
same as the 3-way calling service. It requires LESS to have a
<merge/> command to merge multiple two-party calls into a conference
call.
17.3.10 Consultation call
The Consultation Call service places an existing active call at a
device on hold and initiates a new call from the same device. This is
in fact two actions in LESS, using <Media:mediaupdate/> to put a call
on hold and using <call/> to initiate a new call.
17.3.11 Deflect call
The Deflect Call service allows the computing function to divert a
call to another destination that may be inside or outside the
switching sub-domain. This can be mapped to LESS <transfer/> action.
17.3.12 Dial digits
The Dial Digits service allows the computing function to perform a
dialing sequence that is associated with a call that has already been
initiated. This service is used to send message out after a call
invitation and we use <IM:sendmsg> to handle the action.
17.3.13 Directed pickup call
The Directed Pickup Call service moves a specified call and connects
it at a new specified destination. This results in the connection
being diverted to a new destination inside the switching sub-domain.
This service should not be handled by end systems, but by an
application server in the network.
17.3.14 Group pickup call
The Group Pickup Call service moves a call that is a member of a
specified or default pickup group to a new specified destination. The
same as Directed Pickup Call, this service should be handled by an
application server in the network.
17.3.15 Hold call
The Hold Call service places a connected connection on hold at the
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same device. The <Media:mediaupdate/> action in LESS handles this
service and <enqueue> action can put a call in a queue.
17.3.16 Intrude call
The Intrude Call service adds the calling device to a call at a busy
called device. Depending upon the switching function, the result will
be that the calling device is either actively or silently
participating in the called device's existing call or consulting with
the called device with a new call. This can be handled by LESS
<merge/> action with the <media> modifier set as mode="sendonly" for
silently participating.
17.3.17 Join call
The Join Call service allows a computing function to request, on
behalf of a device, that the device be joined into an existing call.
This can also be handled by LESS <merge/> action.
17.3.18 Make call
The Make Call service allows the computing function to set up a call
between a calling device and a called device. This can be handled by
LESS <call/> action.
17.3.19 Make predictive call
The Make Predictive Call service shall originate a call between two
devices by first creating a connection to the called device. The
service returns a positive acknowledgement that provides the
connection at the called device. Subsequent actions are taken
depending upon the call progress and the actions requested. This
service makes additional actions based on the result of <call/>
action. For example,
<less>
<UI:command command="call">
<call>
<success>
....
</success>
<redirected>
...
</redirected>
<rejected>
...
</rejected>
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</call>
</UI:command>
</less>
17.3.20 Park call
The Park Call service moves a specified call at a device to a
specified (parked-to) destination. Two ways to handle this in an end
system, the first is to transfer the call to a resource server, the
second is to change the media input of the call as described in
Section 17.1.10.
17.3.21 Reconnect call
The Reconnect Call service will clear a specified connection at the
reconnecting device and retrieve a specified held connection at the
same device. This service can be handled by using the action
<terminate/> to terminate an existing call and using
<Media:mediaupdate/> and <dequeue> to retrieve a held call.
17.3.22 Retrieve call
The Retrieve Call service connects a specified held connection. This
can be handled by <dequeue> and <Media:mediaupdate/> actions.
17.3.23 Send message
The Send Message service allows the computing function to send a
message to one or more devices. The message, composed of one or more
MIME body parts, is included in the Send Message service request.
This service can be used to send messages for many different types of
applications (Instant Messaging, Email, Pager, and Short Message
Service (SMS), etc). In LESS, we use <Message:sendmsg/> action to
send a message, and <Email:send/> to send an email.
17.3.24 Single step conference call
The Single Step Conference Call joins a new device into an existing
call. This service can be repeated to make n-device conference calls
(subject to switching function limits). This can be handled by the
action <merge/>.
17.3.25 Single step transfer call
The Single Step Transfer Call service transfers an existing
connection at a device to another device. This transfer is performed
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in a single-step, that is the device doing the transfer does not have
to place the existing call on hold before issuing the Single Step
Transfer Call service. This can be handled by the action
<transfer/>.
17.3.26 Transfer call
The Transfer Call service transfers a call held at a device to an
active call at the same device. The held and active calls at the
transferring device shall be merged into a new call. Also, the
Connections of the held and active calls at the transferring device
shall become Null and their ConnectionIDs shall be released (i.e.,
the transferring device is no longer involved with the call). This
service is in fact merge a held call and an existing call into a 3-
way calling. It should be handled by LESS <merge> action.
17.4 New services
One of the biggest advantage of Internet telephony is its ability to
easily integrate other Internet services, such as presence
information, email, and web. The integration can introduce many new
services which are impossible for PSTN networks. These new services
are not mentioned in Q.1211 or 5ESS service documents.
17.4.1 Email
For email, we usually care about three things, receivers, subject,
and content. We can use <location> or <lookup> modifier to specify
receivers, use subject parameter in <email> action for subject
information, and put content as the data of an <email> tag. For
example,
<location url="mailto:bob@example.com">
<Email:send subject="This is a test">
We simply send this as a test for our LESS scripts.
</Email:send>
</location>
There is no output of the email action.
17.4.2 Web
There are two parameters for a web service action, one is the URI to
visit, the other is the HTTP method. The URI parameter can be handled
by the <location> and <lookup> modifiers. We use different action to
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represent different HTTP methods. For example, <Web:get> represents
HTTP GET method, <Web:post> represents HTTP POST method. Below is a
service example,
<location uri="http://www.example.com">
<Web:get/>
</location>
The output of the a web action can be succeed, redirect, or failed.
17.4.3 Instant messaging
People use instant messaging as a complementary communication method
for voice call and email. We introduce two toplevel actions
<IM::message-coming> for incoming message, <UI:command
command="sendmsg"> for an outgoing message, and one action
<IM::sendmsg> for sending a message out. For example,
<less>
<IM:message-coming>
<address-switch field="origin">
<address is="sip:bob@example.com">
<location url="sip:bob@example.com">
<IM:sendmsg>Hi, Bob</IM:sendmsg>
</location>
</address>
</address-switch>
</IM:message-coming>
</less>
17.4.4 Event subscription and notification
Below is an example for address-based event subscription handling.
<Event:subscription>
<address-switch field="origin">
<address is="sip:bob@example.com">
<Event:approve>
<next>
<Event:notify status="closed"/>
</next>
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</Event:approve>
</address>
</address-switch>
</Event:subscription>
17.4.5 Event notification and event-based services
Event notifications can trigger many new services. For example,
<Event:notification>
<address-switch field="origin">
<address is="sip:bob@example.com">
<Event:event-switch>
<Event:event status="online">
<location url="sip:bob@example.com">
<call/>
</location>
</Event:event>
</Event:event-switch>
</address>
</address-switch>
</Event:notification>
17.4.6 Location-based services
Location information gets more and more important in people's
communications. It is not only used for tracking, but also for
guarding appropriate communication behaviors, triggering
communication actions, and discovering available resources in a
context. Below is an example showing location-based call decision
making.
<incoming>
<Location:where-switch>
<Location:where placytype="movie-theatre">
<alert style="vibrate"/>
</Location:where>
</Location:where-switch>
</incoming>
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18 Feature Interaction Handling Algorithm for LESS Scripts
For LESS-based services, due to the tree-like structure of LESS, we
consider it simple and efficient to design an algorithm to merge
multiple LESS decision trees into one. After merging, for a specific
trigger, there is only one active LESS script at a device. The
merging algorithm is good for single component services. For service
scripts on different devices, for example, the single user multiple
components (SUMC) call control services the merging algorithm can
only detect feature interactions, it cannot merge all the scripts
into one to resolve the interactions. After merging, we will still
keep the original scripts so users can modify them independently.
This way, no conflicts in service execution because for a given
trigger, it only needs to go through one decision tree to perform
services. In the mean time, we can still ensure the service
modularity so users can create their services efficiently.
18.1 Tree merging algorithm
The overall multi-script merging process is as below.
set base-rule-set empty
foreach LESS-tree {
convert the LESS-tree into a rule set
foreach rule in the rule set {
normalize the rule
}
merge the normalized rule set into base-rule-set
}
convert base-rule-set into a decision tree
The merging operation is in fact to merge every set of rules into
base-rule-set, then convert the base-rule-set back to a decision
tree. We will explain every step of the process below.
A rule of a LESS decision tree is defined as which actions get
executed under a certain condition for a specific trigger. Based on
the LESS design principles we introduced in Section 2.1, the path
from the root of a decision tree to each leaf node consists a
decision rule. We construct a rule as a composition of a trigger,
the actions in accordance to the trigger, and a list of switch nodes
that in the path from the root to the action node, we name the list
of switch nodes rule path. For example, for the script below, we can
represent a decision rule as "{incoming,accept,{{string-
switch,organization="ABC Inc."},{address-switch,
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origin="sip:tom@abc.com"},{string-switch,subject="group meeting"}}}".
<less>
<incoming>
<string-switch field="organization">
<string is="ABC Inc.">
<address-switch field="origin">
<address is="sip:tom@abc.com">
<string-switch field="subject">
<string is="group meeting">
<accept/>
</string>
</string-switch>
</address>
<otherwise>
<location url="sip:tom@voicemail.abc.com">
<redirect/>
</location>
</otherwise>
</address-switch>
</string>
</string-switch>
</incoming>
</less>
To facilitate rule merging, we need to normalize the rules generated
from LESS decision trees. The normalization process sorts rule paths
to a specific order, e.g., in the order of "address-switch", "time-
switch", "status-switch", "string-switch", "priority-switch",
"where-switch", and "language-switch". It will also merge the switch
nodes with the same switch name into one node in a rule path. For
example, a normalized rule for the script above is "{incoming,
accept, {address-switch, origin="sip:tom@abc.com"},
{string-switch, subject="ABC group meeting", organization="ABC
Inc."}}". Because switches are independent of each other, normalized
rules are functionally equal to original rules. After normalization,
we can follow the process below to detect feature interactions
between two normalized rules.
if (two rules have different triggers) {
no rule conflict
} elseif actions in two rules do not conflict {
no rule conflict
} elseif no overlap between rule path in two rules {
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no rule conflict
} else {
two rules conflict with each other,
return the rule path overlap and action conflict information
prompt to the script owner to judge
}
During the process, we use the action conflict table defined in our
technical report "Feature Interactions in Internet Telephony End
Systems" [15]. to check whether two actions interact with each other
or not. If actions in two rules conflict with each other, we need to
check whether there are conditions matching both rule paths. We name
this kind of conditions the overlap between two rule paths. We
employ the following algorithm to get the overlap.
set overlap-set empty
foreach switch-node1 in rule-path1 {
if there is a switch-node2 in rule-path2 has the same switch name {
if the switch-overlap between switch-node1 and switch-node2 is empty {
return empty overlap-set
} else {
insert the switch-overlap into overlap-set
}
} else {
insert switch-node1 into overlap-set
}
}
foreach switch-node2 in rule-path2 {
if there is not a switch-node1 in rule-path1 has the same switch name {
insert switch-node2 into overlap-set
}
}
return overlap-set
During the overlap handling process, different switch types have
different overlap detection method. We will not detail the overlap
handling for each switch type in this paper.
Once we find the overlap-set and the conflicting actions, we can
present the information to users to make decisions. We can record
the decision made by the user and build a normalized rule set without
conflicts.
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To convert a set of normalized rules back to a decision tree is
straightforward. The pseudo code below shows the algorithm.
set tree empty
foreach rule in the merged rule set {
foreach switch node in the rule path {
//since each rule is normalized, the switch node appears in order
go along the tree from the root
if the switch node matches a tree node {
go to the matched branch, and continue for the next switch node
} else {
if there is an unmatched branch {
go to unmatched branch, continue the test
} else {
create an unmatched branch
put the rest rule path (including current switch node)
in the unmatched branch
}}}}
19 The XML Schema for LESS and Commonly Used Extensions
19.1 XML Schema for LESS
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:ietf:params:xml:ns:less" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:complexType name="TriggerType" abstract="true">
<xs:group ref="Node"/>
</xs:complexType>
<xs:element name="trigger" type="TriggerType"/>
<xs:complexType name="ActionType" abstract="true" mixed="true">
<xs:all>
<xs:element name="next" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
</xs:complexType>
<xs:element name="action" type="ActionType"/>
<xs:complexType name="SwitchType" abstract="true"/>
<xs:element name="switch" type="SwitchType"/>
<xs:complexType name="ModifierType" abstract="true"/>
<xs:element name="modifier" type="ModifierType"/>
<xs:complexType name="SubAction">
<xs:attribute name="ref" type="xs:string" use="required"/>
</xs:complexType>
<xs:element name="sub" type="SubAction"/>
<xs:complexType name="SubactionType">
<xs:group ref="Node"/>
<xs:attribute name="id" use="required"/>
</xs:complexType>
<xs:complexType name="AncillaryType"/>
<xs:group name="Node">
<xs:choice>
<xs:element ref="switch" minOccurs="0"/>
<xs:element ref="modifier" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="sub" minOccurs="0"/>
<xs:element ref="action" minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
</xs:group>
<xs:complexType name="OtherwiseAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:complexType name="NotPresentAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:complexType name="LESSType">
<xs:sequence>
<xs:element name="ancillary" type="AncillaryType" minOccurs="0"/>
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<xs:element name="subaction" type="SubactionType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="trigger" minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>Any toplevel action MUST NOT appear more than once.</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element name="less" type="LESSType"/>
<xs:simpleType name="YesNoType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="yes"/>
<xs:enumeration value="no"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="StatusType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="busy"/>
<xs:enumeration value="notfound"/>
<xs:enumeration value="reject"/>
<xs:enumeration value="error"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:complexType name="IncomingType">
<xs:complexContent>
<xs:extension base="TriggerType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="incoming" type="IncomingType" substitutionGroup="trigger"/>
<xs:complexType name="TimerType">
<xs:complexContent>
<xs:extension base="TriggerType">
<xs:attribute name="dtstart" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="dtend" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
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</xs:attribute>
<xs:attribute name="duration" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DURATION</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="freq" type="FreqType" use="optional"/>
<xs:attribute name="interval" type="xs:positiveInteger" default="1"/>
<xs:attribute name="until" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="count" type="xs:positiveInteger" use="optional"/>
<xs:attribute name="bysecond" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of seconds within a minute. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byminute" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of minutes within an hour. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byhour" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of hours of the day. Valid values are 0 to 23.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the week. Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". These values are not case-sensitive. Each can be preceded by a positive (+n) or negative (-n) integer.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonthday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the month. Valid values are 1 to 31 or -31 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byyearday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the year. Valid values are 1 to 366 or -366 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byweekno" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of ordinals specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.</xs:documentation>
</xs:annotation>
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</xs:attribute>
<xs:attribute name="bymonth" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of months of the year. Valid values are 1 to 12.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="wkst" type="DayType" default="MO"/>
<xs:attribute name="bysetpos" type="YearDayType"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="timer" type="TimerType" substitutionGroup="trigger"/>
<xs:simpleType name="OrderingType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="parallel"/>
<xs:enumeration value="sequential"/>
<xs:enumeration value="first-only"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="AddressFieldType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="origin"/>
<xs:enumeration value="destination"/>
<xs:enumeration value="original-destination"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:simpleType name="AddressSubfieldType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="address-type"/>
<xs:enumeration value="user"/>
<xs:enumeration value="host"/>
<xs:enumeration value="port"/>
<xs:enumeration value="tel"/>
<xs:enumeration value="display"/>
<xs:enumeration value="password"/>
<xs:enumeration value="alias-type"/>
</xs:restriction>
</xs:simpleType>
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<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:complexType name="AddressType">
<xs:annotation>
<xs:documentation>Exactly one of the three attributes must appear</xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>for "display" only</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="subdomain-of" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>for "host", "tel" only</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="AddressSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="address" type="AddressType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="address" type="AddressType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="AddressFieldType" use="required"/>
<xs:attribute name="subfield" type="AddressSubfieldType" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="address-switch" type="AddressSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="StringFieldType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="subject"/>
<xs:enumeration value="organization"/>
<xs:enumeration value="user-agent"/>
<xs:enumeration value="display"/>
</xs:restriction>
</xs:simpleType>
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<xs:complexType name="StringType">
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="StringSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="string" type="StringType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="string" type="StringType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="StringFieldType" use="required">
<xs:annotation>
<xs:documentation>Strings are matched as case-insensitive Unicode strings.</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="string-switch" type="StringSwitchType" substitutionGroup="switch"/>
<xs:complexType name="LanguageType">
<xs:group ref="Node"/>
<xs:attribute name="matches" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>The value of one of these parameters is a language-tag, as defined in RFC 3066.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="LanguageSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="language" type="LanguageType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="language" type="LanguageType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
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</xs:complexType>
<xs:element name="language-switch" type="LanguageSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="FreqType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[s|S][e|E][c|C][o|O][n|N][d|D][l|L][y|Y]"/>
<xs:pattern value="[m|M][i|I][n|N][u|U][t|T][e|E][l|L][y|Y]"/>
<xs:pattern value="[h|H][o|O][u|U][r|R][l|L][y|Y]"/>
<xs:pattern value="[d|D][a|A][i|I][l|L][y|Y]"/>
<xs:pattern value="[w|W][e|E][e|E][k|K][l|L][y|Y]"/>
<xs:pattern value="[m|M][o|N][n|N][t|T][h|H][l|L][y|Y]"/>
<xs:pattern value="[y|Y][e|E][a|A][r|R][l|L][y|Y]"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="YearDayType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="-366"/>
<xs:maxInclusive value="-1"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="1"/>
<xs:maxExclusive value="366"/>
</xs:restriction>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:simpleType name="DayType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[m|M][o|O]"/>
<xs:pattern value="[t|T][u|U]"/>
<xs:pattern value="[w|W][e|E]"/>
<xs:pattern value="[t|T][h|H]"/>
<xs:pattern value="[f|F][r|R]"/>
<xs:pattern value="[s|S][a|A]"/>
<xs:pattern value="[s|S][u|U]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TimeType">
<xs:annotation>
<xs:documentation>Exactly one of the two attributes "dtend" and "duration" must occur. None of the attributes following freq are meaningful unless freq appears. </xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="dtstart" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
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</xs:annotation>
</xs:attribute>
<xs:attribute name="dtend" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="duration" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DURATION</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="freq" type="FreqType" use="optional"/>
<xs:attribute name="interval" type="xs:positiveInteger" default="1"/>
<xs:attribute name="until" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="count" type="xs:positiveInteger" use="optional"/>
<xs:attribute name="bysecond" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of seconds within a minute. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byminute" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of minutes within an hour. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byhour" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of hours of the day. Valid values are 0 to 23.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the week. Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". These values are not case-sensitive. Each can be preceded by a positive (+n) or negative (-n) integer.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonthday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the month. Valid values are 1 to 31 or -31 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byyearday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the year. Valid values are 1 to 366 or -366 to -1.</xs:documentation>
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</xs:annotation>
</xs:attribute>
<xs:attribute name="byweekno" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of ordinals specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonth" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of months of the year. Valid values are 1 to 12.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="wkst" type="DayType" default="MO"/>
<xs:attribute name="bysetpos" type="YearDayType"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:simpleType name="TZIDType">
<xs:restriction base="xs:string"/>
</xs:simpleType>
<xs:simpleType name="TZURLType">
<xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:complexType name="TimeSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="time" type="TimeType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="time" type="TimeType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="tzid" type="TZIDType"/>
<xs:attribute name="tzurl" type="TZURLType"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="time-switch" type="TimeSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="PriorityValues">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[e|E][m|M][e|E][r|R][g|G][e|E][n|N][c|C][y|Y]"/>
<xs:pattern value="[u|U][r|R][g|G][e|E][n|N][t|T]"/>
<xs:pattern value="[n|N][o|O][r|R][m|M][a|A][l|L]"/>
<xs:pattern value="[n|N][o|O][n|N]-[u|U][r|R][g|G][e|E][n|N][t|T]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="PriorityType">
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<xs:annotation>
<xs:documentation>Exactly one of the three attributes must appear </xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="less" type="PriorityValues"/>
<xs:attribute name="greater" type="PriorityValues"/>
<xs:attribute name="equal" type="xs:string">
<xs:annotation>
<xs:documentation>case-insensitive</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="PrioritySwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="priority" type="PriorityType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="priority" type="PriorityType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="priority-switch" type="PrioritySwitchType" substitutionGroup="switch"/>
<xs:complexType name="UserStatusType">
<xs:group ref="Node"/>
<xs:attribute name="less" type="xs:integer"/>
<xs:attribute name="greater" type="xs:integer"/>
<xs:attribute name="equal" type="xs:integer"/>
<xs:attribute name="is">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="contains">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
<xs:complexType name="StatusSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
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<xs:element name="status" type="UserStatusType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="status" type="UserStatusType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="uri" type="xs:anyURI" use="optional"/>
<xs:attribute name="status-name">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="active-calls"/>
<xs:enumeration value="presence"/>
<xs:enumeration value="activity"/>
<xs:enumeration value="mood"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="status-switch" type="StatusSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="LocationPriorityType">
<xs:restriction base="xs:float">
<xs:minInclusive value="0.0"/>
<xs:maxInclusive value="1.0"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="LocationType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
<xs:attribute name="priority" type="LocationPriorityType" use="optional" default="1.0"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="location" type="LocationType" substitutionGroup="modifier"/>
<xs:complexType name="LookupType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
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<xs:element name="notfound" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="source" type="xs:string" use="required"/>
<xs:attribute name="order" use="optional" default="parallel">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="parallel"/>
<xs:enumeration value="sequential"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="timeout" type="xs:positiveInteger" default="30"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="lookup" type="LookupType" substitutionGroup="modifier"/>
<xs:complexType name="RemoveLocationType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:group ref="Node"/>
<xs:attribute name="location" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="remove-location" type="RemoveLocationType" substitutionGroup="modifier"/>
<xs:complexType name="LogAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="name" type="xs:string" use="optional"/>
<xs:attribute name="comment" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="log" type="LogAction" substitutionGroup="action"/>
<xs:complexType name="MailAction">
<xs:complexContent>
<xs:extension base="ActionType">
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<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="mail" type="MailAction" substitutionGroup="action"/>
<xs:complexType name="WaitAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="duration" type="xs:duration" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="wait" type="WaitAction" substitutionGroup="action"/>
<xs:complexType name="AcceptActionType">
<xs:complexContent>
<xs:extension base="ActionType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="accept" type="AcceptActionType" substitutionGroup="action"/>
<xs:complexType name="RedirectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="permanent" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="redirect" type="RedirectAction" substitutionGroup="action"/>
<xs:complexType name="RejectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="status" type="StatusType" use="required"/>
<xs:attribute name="reason" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="reject" type="RejectAction" substitutionGroup="action"/>
<xs:complexType name="AuthenticateAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
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<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="method" use="optional" default="digest">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="digest"/>
<xs:enumeration value="basic"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="realm" type="xs:string"/>
<xs:attribute name="user" type="xs:string"/>
<xs:attribute name="target">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="remote"/>
<xs:enumeration value="local"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="authenticate" type="AuthenticateAction" substitutionGroup="action"/>
<xs:complexType name="CallActionType">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:all>
<xs:element name="accepted" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="busy" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
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<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="call" type="CallActionType" substitutionGroup="action"/>
<xs:complexType name="TerminateActionType">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="uri">
<xs:simpleType>
<xs:list itemType="xs:anyURI"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="subject">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="calls">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="all"/>
<xs:enumeration value="last"/>
<xs:enumeration value="this"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="terminate" type="TerminateActionType" substitutionGroup="action"/>
</xs:schema>
19.2 XML Schema for LESS Media Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="urn:ietf:params:xml:ns:less" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:complexType name="TriggerType" abstract="true">
<xs:group ref="Node"/>
</xs:complexType>
<xs:element name="trigger" type="TriggerType"/>
<xs:complexType name="ActionType" abstract="true" mixed="true">
<xs:all>
<xs:element name="next" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
</xs:complexType>
<xs:element name="action" type="ActionType"/>
<xs:complexType name="SwitchType" abstract="true"/>
<xs:element name="switch" type="SwitchType"/>
<xs:complexType name="ModifierType" abstract="true"/>
<xs:element name="modifier" type="ModifierType"/>
<xs:complexType name="SubAction">
<xs:attribute name="ref" type="xs:string" use="required"/>
</xs:complexType>
<xs:element name="sub" type="SubAction"/>
<xs:complexType name="SubactionType">
<xs:group ref="Node"/>
<xs:attribute name="id" use="required"/>
</xs:complexType>
<xs:complexType name="AncillaryType"/>
<xs:group name="Node">
<xs:choice>
<xs:element ref="switch" minOccurs="0"/>
<xs:element ref="modifier" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="sub" minOccurs="0"/>
<xs:element ref="action" minOccurs="0" maxOccurs="unbounded"/>
</xs:choice>
</xs:group>
<xs:complexType name="OtherwiseAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:complexType name="NotPresentAction">
<xs:group ref="Node"/>
</xs:complexType>
<xs:complexType name="LESSType">
<xs:sequence>
<xs:element name="ancillary" type="AncillaryType" minOccurs="0"/>
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<xs:element name="subaction" type="SubactionType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="trigger" minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>Any toplevel action MUST NOT appear more than once.</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:element name="less" type="LESSType"/>
<xs:simpleType name="YesNoType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="yes"/>
<xs:enumeration value="no"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="StatusType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="busy"/>
<xs:enumeration value="notfound"/>
<xs:enumeration value="reject"/>
<xs:enumeration value="error"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:complexType name="IncomingType">
<xs:complexContent>
<xs:extension base="TriggerType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="incoming" type="IncomingType" substitutionGroup="trigger"/>
<xs:complexType name="TimerType">
<xs:complexContent>
<xs:extension base="TriggerType">
<xs:attribute name="dtstart" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="dtend" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
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</xs:attribute>
<xs:attribute name="duration" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DURATION</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="freq" type="FreqType" use="optional"/>
<xs:attribute name="interval" type="xs:positiveInteger" default="1"/>
<xs:attribute name="until" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="count" type="xs:positiveInteger" use="optional"/>
<xs:attribute name="bysecond" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of seconds within a minute. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byminute" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of minutes within an hour. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byhour" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of hours of the day. Valid values are 0 to 23.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the week. Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". These values are not case-sensitive. Each can be preceded by a positive (+n) or negative (-n) integer.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonthday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the month. Valid values are 1 to 31 or -31 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byyearday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the year. Valid values are 1 to 366 or -366 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byweekno" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of ordinals specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.</xs:documentation>
</xs:annotation>
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</xs:attribute>
<xs:attribute name="bymonth" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of months of the year. Valid values are 1 to 12.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="wkst" type="DayType" default="MO"/>
<xs:attribute name="bysetpos" type="YearDayType"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="timer" type="TimerType" substitutionGroup="trigger"/>
<xs:simpleType name="OrderingType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="parallel"/>
<xs:enumeration value="sequential"/>
<xs:enumeration value="first-only"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="AddressFieldType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="origin"/>
<xs:enumeration value="destination"/>
<xs:enumeration value="original-destination"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:simpleType name="AddressSubfieldType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="address-type"/>
<xs:enumeration value="user"/>
<xs:enumeration value="host"/>
<xs:enumeration value="port"/>
<xs:enumeration value="tel"/>
<xs:enumeration value="display"/>
<xs:enumeration value="password"/>
<xs:enumeration value="alias-type"/>
</xs:restriction>
</xs:simpleType>
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<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:complexType name="AddressType">
<xs:annotation>
<xs:documentation>Exactly one of the three attributes must appear</xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>for "display" only</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="subdomain-of" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>for "host", "tel" only</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="AddressSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="address" type="AddressType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="address" type="AddressType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="AddressFieldType" use="required"/>
<xs:attribute name="subfield" type="AddressSubfieldType" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="address-switch" type="AddressSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="StringFieldType">
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="subject"/>
<xs:enumeration value="organization"/>
<xs:enumeration value="user-agent"/>
<xs:enumeration value="display"/>
</xs:restriction>
</xs:simpleType>
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<xs:complexType name="StringType">
<xs:group ref="Node"/>
<xs:attribute name="is" type="xs:string" use="optional"/>
<xs:attribute name="contains" type="xs:string" use="optional"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="StringSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="string" type="StringType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="string" type="StringType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="field" type="StringFieldType" use="required">
<xs:annotation>
<xs:documentation>Strings are matched as case-insensitive Unicode strings.</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="string-switch" type="StringSwitchType" substitutionGroup="switch"/>
<xs:complexType name="LanguageType">
<xs:group ref="Node"/>
<xs:attribute name="matches" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>The value of one of these parameters is a language-tag, as defined in RFC 3066.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="LanguageSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="language" type="LanguageType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="language" type="LanguageType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
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</xs:complexType>
<xs:element name="language-switch" type="LanguageSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="FreqType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[s|S][e|E][c|C][o|O][n|N][d|D][l|L][y|Y]"/>
<xs:pattern value="[m|M][i|I][n|N][u|U][t|T][e|E][l|L][y|Y]"/>
<xs:pattern value="[h|H][o|O][u|U][r|R][l|L][y|Y]"/>
<xs:pattern value="[d|D][a|A][i|I][l|L][y|Y]"/>
<xs:pattern value="[w|W][e|E][e|E][k|K][l|L][y|Y]"/>
<xs:pattern value="[m|M][o|N][n|N][t|T][h|H][l|L][y|Y]"/>
<xs:pattern value="[y|Y][e|E][a|A][r|R][l|L][y|Y]"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="YearDayType">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="-366"/>
<xs:maxInclusive value="-1"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="1"/>
<xs:maxExclusive value="366"/>
</xs:restriction>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:simpleType name="DayType">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[m|M][o|O]"/>
<xs:pattern value="[t|T][u|U]"/>
<xs:pattern value="[w|W][e|E]"/>
<xs:pattern value="[t|T][h|H]"/>
<xs:pattern value="[f|F][r|R]"/>
<xs:pattern value="[s|S][a|A]"/>
<xs:pattern value="[s|S][u|U]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TimeType">
<xs:annotation>
<xs:documentation>Exactly one of the two attributes "dtend" and "duration" must occur. None of the attributes following freq are meaningful unless freq appears. </xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="dtstart" type="xs:string" use="required">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
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</xs:annotation>
</xs:attribute>
<xs:attribute name="dtend" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="duration" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DURATION</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="freq" type="FreqType" use="optional"/>
<xs:attribute name="interval" type="xs:positiveInteger" default="1"/>
<xs:attribute name="until" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>RFC 2445 DATE-TIME</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="count" type="xs:positiveInteger" use="optional"/>
<xs:attribute name="bysecond" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of seconds within a minute. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byminute" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of minutes within an hour. Valid values are 0 to 59.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byhour" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of hours of the day. Valid values are 0 to 23.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the week. Valid values are "MO", "TU", "WE", "TH", "FR", "SA" and "SU". These values are not case-sensitive. Each can be preceded by a positive (+n) or negative (-n) integer.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonthday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the month. Valid values are 1 to 31 or -31 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="byyearday" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of days of the year. Valid values are 1 to 366 or -366 to -1.</xs:documentation>
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</xs:annotation>
</xs:attribute>
<xs:attribute name="byweekno" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of ordinals specifying weeks of the year. Valid values are 1 to 53 or -53 to -1.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="bymonth" type="xs:string" use="optional">
<xs:annotation>
<xs:documentation>Comma-separated list of months of the year. Valid values are 1 to 12.</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="wkst" type="DayType" default="MO"/>
<xs:attribute name="bysetpos" type="YearDayType"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:simpleType name="TZIDType">
<xs:restriction base="xs:string"/>
</xs:simpleType>
<xs:simpleType name="TZURLType">
<xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:complexType name="TimeSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="time" type="TimeType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="time" type="TimeType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="tzid" type="TZIDType"/>
<xs:attribute name="tzurl" type="TZURLType"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="time-switch" type="TimeSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="PriorityValues">
<xs:restriction base="xs:NMTOKEN">
<xs:pattern value="[e|E][m|M][e|E][r|R][g|G][e|E][n|N][c|C][y|Y]"/>
<xs:pattern value="[u|U][r|R][g|G][e|E][n|N][t|T]"/>
<xs:pattern value="[n|N][o|O][r|R][m|M][a|A][l|L]"/>
<xs:pattern value="[n|N][o|O][n|N]-[u|U][r|R][g|G][e|E][n|N][t|T]"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="PriorityType">
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<xs:annotation>
<xs:documentation>Exactly one of the three attributes must appear </xs:documentation>
</xs:annotation>
<xs:group ref="Node"/>
<xs:attribute name="less" type="PriorityValues"/>
<xs:attribute name="greater" type="PriorityValues"/>
<xs:attribute name="equal" type="xs:string">
<xs:annotation>
<xs:documentation>case-insensitive</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:complexType>
<xs:complexType name="PrioritySwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
<xs:element name="priority" type="PriorityType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="priority" type="PriorityType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="priority-switch" type="PrioritySwitchType" substitutionGroup="switch"/>
<xs:complexType name="UserStatusType">
<xs:group ref="Node"/>
<xs:attribute name="less" type="xs:integer"/>
<xs:attribute name="greater" type="xs:integer"/>
<xs:attribute name="equal" type="xs:integer"/>
<xs:attribute name="is">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="contains">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
<xs:complexType name="StatusSwitchType">
<xs:complexContent>
<xs:extension base="SwitchType">
<xs:sequence>
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<xs:element name="status" type="UserStatusType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="NotPresentAction"/>
<xs:element name="status" type="UserStatusType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="uri" type="xs:anyURI" use="optional"/>
<xs:attribute name="status-name">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="active-calls"/>
<xs:enumeration value="presence"/>
<xs:enumeration value="activity"/>
<xs:enumeration value="mood"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="status-switch" type="StatusSwitchType" substitutionGroup="switch"/>
<xs:simpleType name="LocationPriorityType">
<xs:restriction base="xs:float">
<xs:minInclusive value="0.0"/>
<xs:maxInclusive value="1.0"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="LocationType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
<xs:attribute name="priority" type="LocationPriorityType" use="optional" default="1.0"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="location" type="LocationType" substitutionGroup="modifier"/>
<xs:complexType name="LookupType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
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<xs:element name="notfound" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="source" type="xs:string" use="required"/>
<xs:attribute name="order" use="optional" default="parallel">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="parallel"/>
<xs:enumeration value="sequential"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="timeout" type="xs:positiveInteger" default="30"/>
<xs:attribute name="clear" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="lookup" type="LookupType" substitutionGroup="modifier"/>
<xs:complexType name="RemoveLocationType">
<xs:complexContent>
<xs:extension base="ModifierType">
<xs:group ref="Node"/>
<xs:attribute name="location" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="remove-location" type="RemoveLocationType" substitutionGroup="modifier"/>
<xs:complexType name="LogAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="name" type="xs:string" use="optional"/>
<xs:attribute name="comment" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="log" type="LogAction" substitutionGroup="action"/>
<xs:complexType name="MailAction">
<xs:complexContent>
<xs:extension base="ActionType">
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<xs:group ref="Node"/>
<xs:attribute name="url" type="xs:anyURI" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="mail" type="MailAction" substitutionGroup="action"/>
<xs:complexType name="WaitAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="duration" type="xs:duration" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="wait" type="WaitAction" substitutionGroup="action"/>
<xs:complexType name="AcceptActionType">
<xs:complexContent>
<xs:extension base="ActionType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="accept" type="AcceptActionType" substitutionGroup="action"/>
<xs:complexType name="RedirectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="permanent" type="YesNoType" default="no"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="redirect" type="RedirectAction" substitutionGroup="action"/>
<xs:complexType name="RejectAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:attribute name="status" type="StatusType" use="required"/>
<xs:attribute name="reason" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="reject" type="RejectAction" substitutionGroup="action"/>
<xs:complexType name="AuthenticateAction">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
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<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="method" use="optional" default="digest">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="digest"/>
<xs:enumeration value="basic"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="realm" type="xs:string"/>
<xs:attribute name="user" type="xs:string"/>
<xs:attribute name="target">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="remote"/>
<xs:enumeration value="local"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="authenticate" type="AuthenticateAction" substitutionGroup="action"/>
<xs:complexType name="CallActionType">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:all>
<xs:element name="accepted" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="busy" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
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<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="call" type="CallActionType" substitutionGroup="action"/>
<xs:complexType name="TerminateActionType">
<xs:complexContent>
<xs:extension base="ActionType">
<xs:group ref="Node"/>
<xs:attribute name="uri">
<xs:simpleType>
<xs:list itemType="xs:anyURI"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="subject">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="calls">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="all"/>
<xs:enumeration value="last"/>
<xs:enumeration value="this"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="terminate" type="TerminateActionType" substitutionGroup="action"/>
</xs:schema>
19.3 XML Schema for LESS Mid-call handling Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<!-- edited with XML Spy v4.3 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:midcall" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" xmlns="urn:ietf:params:xml:ns:less:midcall">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:complexType name="TransferActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="accepted" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="busy" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger" use="optional" default="20"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="transfer" type="TransferActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="MergeAction">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:attribute name="uri">
<xs:simpleType>
<xs:list itemType="xs:anyURI"/>
</xs:simpleType>
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</xs:attribute>
<xs:attribute name="subject">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="merge" type="MergeAction" substitutionGroup="LESS:action"/>
</xs:schema>
19.4 XML Schema for LESS User Interaction Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<!-- edited with XML Spy v4.3 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:ui" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" xmlns="urn:ietf:params:xml:ns:less:ui">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:complexType name="CommandType">
<xs:complexContent>
<xs:extension base="LESS:TriggerType">
<xs:attribute name="command" type="xs:string" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="command" type="CommandType" substitutionGroup="LESS:trigger"/>
<xs:complexType name="AlertActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="timeout" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="duration" type="xs:dateTime" use="optional"/>
<xs:attribute name="priority" type="LESS:PriorityValues" use="optional"/>
<xs:attribute name="message" type="xs:string" use="optional"/>
<xs:attribute name="icon" type="xs:string" use="optional"/>
<xs:attribute name="input" type="xs:anyURI" use="optional"/>
<xs:attribute name="style" use="optional" default="sound">
<xs:simpleType>
<xs:list>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="viberate"/>
<xs:enumeration value="flash"/>
<xs:enumeration value="sound"/>
<xs:enumeration value="text"/>
</xs:restriction>
</xs:simpleType>
</xs:list>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="alert" type="AlertActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="GetinputActionType">
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<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:duration" use="optional"/>
<xs:attribute name="source" use="optional">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="screen"/>
<xs:enumeration value="audio"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="target" use="optional">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="remote"/>
<xs:enumeration value="local"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="getinput" type="GetinputActionType" substitutionGroup="LESS:action"/>
</xs:schema>
19.5 XML Schema for LESS Instant Messaging Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<!-- edited with XML Spy v4.3 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:im" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" xmlns="urn:ietf:params:xml:ns:less:im">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:complexType name="MessageType">
<xs:complexContent>
<xs:extension base="LESS:TriggerType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="message" type="MessageType" substitutionGroup="LESS:trigger"/>
<xs:complexType name="SendmsgActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:attribute name="type">
<xs:simpleType>
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="dtmf"/>
<xs:enumeration value="text"/>
<xs:enumeration value="image"/>
<xs:enumeration value="file"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="message" type="xs:string"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="sendmsg" type="SendmsgActionType" substitutionGroup="LESS:action"/>
</xs:schema>
19.6 XML Schema for LESS Event Handling Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:event" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" xmlns="urn:ietf:params:xml:ns:less:event" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:element name="subscription" type="SubscriptionType" substitutionGroup="LESS:trigger"/>
<xs:complexType name="SubscriptionType">
<xs:complexContent>
<xs:extension base="LESS:TriggerType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="notification" type="NotificationType" substitutionGroup="LESS:trigger"/>
<xs:complexType name="NotificationType">
<xs:complexContent>
<xs:extension base="LESS:TriggerType"/>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="EventType">
<xs:group ref="LESS:Node"/>
<xs:attribute name="package" use="required">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="is" use="optional">
<xs:simpleType>
<xs:list itemType="xs:string"/>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
<xs:complexType name="EventSwitchType">
<xs:sequence>
<xs:element name="event" type="EventType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="LESS:NotPresentAction"/>
<xs:element name="event" type="EventType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="LESS:OtherwiseAction" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="event-switch" type="EventSwitchType" substitutionGroup="LESS:switch"/>
<xs:complexType name="ApproveActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:attribute name="expires" type="xs:integer">
<xs:annotation>
<xs:documentation>Expiration in seconds</xs:documentation>
</xs:annotation>
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</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="approve" type="ApproveActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="DenyActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:attribute name="reason" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="deny" type="DenyActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="DeferActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType"/>
</xs:complexContent>
</xs:complexType>
<xs:element name="defer" type="DeferActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="SubscribeActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="approved" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="denied" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="pending" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
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<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger" use="optional" default="20"/>
<xs:attribute name="expires" type="xs:integer">
<xs:annotation>
<xs:documentation>Expiration in seconds</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="package" type="xs:string" use="required"/>
<xs:attribute name="content" type="xs:string" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="subscribe" type="SubscribeActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="NotifyActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="accepted" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="redirection" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="noanswer" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="LESS:Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="timeout" type="xs:positiveInteger" use="optional" default="20"/>
<xs:attribute name="package" type="xs:string" use="required"/>
<xs:attribute name="event" type="xs:string" use="required"/>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:extension>
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</xs:complexContent>
</xs:complexType>
<xs:element name="notify" type="NotifyActionType" substitutionGroup="LESS:action"/>
</xs:schema>
19.7 XML Schema for LESS Location-based Services Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:location" xmlns="urn:ietf:params:xml:ns:less:location" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:complexType name="WhereSwitchType">
<xs:sequence>
<xs:element name="where" type="WhereType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="LESS:NotPresentAction"/>
<xs:element name="where" type="WhereType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="LESS:OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="type" use="required">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="geospatial"/>
<xs:enumeration value="civil"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="uri" type="xs:anyURI"/>
</xs:complexType>
<xs:element name="where-switch" type="WhereSwitchType" substitutionGroup="LESS:switch"/>
<xs:complexType name="WhereType">
<xs:group ref="LESS:Node"/>
<xs:attribute name="changed" type="xs:boolean" default="true"/>
<xs:attribute name="longitude" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is geospatial</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="latitude" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is geospatial</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="altitude" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is geospatial</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="A1" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
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<xs:attribute name="A2" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="A3" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="A4" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="A5" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="A6" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="PRD" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="POD" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="STS" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="HNO" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="HNS" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
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</xs:annotation>
</xs:attribute>
<xs:attribute name="LMK" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="LOC" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="FLR" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="NAM" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="PC" type="xs:string">
<xs:annotation>
<xs:documentation>Valid only if type is civil</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="distance">
<xs:annotation>
<xs:documentation>Valid only if geospatial or civil location presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:decimal">
<xs:minInclusive value="0"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="condition" default="at">
<xs:annotation>
<xs:documentation>Valid only if distance presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="in"/>
<xs:enumeration value="out"/>
<xs:enumeration value="at"/>
</xs:restriction>
</xs:simpleType>
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</xs:attribute>
<xs:attribute name="unit" default="m">
<xs:annotation>
<xs:documentation>Valid only if distance presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="m"/>
<xs:enumeration value="km"/>
<xs:enumeration value="mi"/>
<xs:enumeration value="in"/>
<xs:enumeration value="ft"/>
<xs:enumeration value="yd"/>
<xs:enumeration value="naut mi"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="direction">
<xs:annotation>
<xs:documentation>Valid only if geospatial or civil location presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="south"/>
<xs:enumeration value="north"/>
<xs:enumeration value="east"/>
<xs:enumeration value="west"/>
<xs:enumeration value="above"/>
<xs:enumeration value="below"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:complexType>
<xs:complexType name="WhereRelationSwitchType">
<xs:sequence>
<xs:element name="where-relation" type="WhereRelationType" minOccurs="0" maxOccurs="unbounded"/>
<xs:sequence minOccurs="0">
<xs:element name="not-present" type="LESS:NotPresentAction"/>
<xs:element name="where-relation" type="WhereRelationType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:element name="otherwise" type="LESS:OtherwiseAction" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="uri1" type="xs:anyURI" use="required"/>
<xs:attribute name="uri2" type="xs:anyURI"/>
</xs:complexType>
<xs:element name="where-relation-switch" type="WhereRelationSwitchType" substitutionGroup="LESS:switch"/>
<xs:simpleType name="WhereAttributes">
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<xs:restriction base="xs:string">
<xs:enumeration value="latitude"/>
<xs:enumeration value="longitude"/>
<xs:enumeration value="altitude"/>
<xs:enumeration value="country"/>
<xs:enumeration value="A1"/>
<xs:enumeration value="A2"/>
<xs:enumeration value="A3"/>
<xs:enumeration value="A4"/>
<xs:enumeration value="A5"/>
<xs:enumeration value="A6"/>
<xs:enumeration value="PRD"/>
<xs:enumeration value="POD"/>
<xs:enumeration value="STS"/>
<xs:enumeration value="HNO"/>
<xs:enumeration value="HNS"/>
<xs:enumeration value="LMK"/>
<xs:enumeration value="LOC"/>
<xs:enumeration value="FLR"/>
<xs:enumeration value="NAM"/>
<xs:enumeration value="PC"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="WhereRelationType">
<xs:group ref="LESS:Node"/>
<xs:attribute name="distance">
<xs:annotation>
<xs:documentation>Valid only if geospatial or civil location presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:decimal">
<xs:minInclusive value="0"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="condition" default="at">
<xs:annotation>
<xs:documentation>Valid only if distance presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="in"/>
<xs:enumeration value="out"/>
<xs:enumeration value="at"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="unit" default="m">
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<xs:annotation>
<xs:documentation>Valid only if distance presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="m"/>
<xs:enumeration value="km"/>
<xs:enumeration value="mi"/>
<xs:enumeration value="in"/>
<xs:enumeration value="ft"/>
<xs:enumeration value="yd"/>
<xs:enumeration value="naut mi"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="direction">
<xs:annotation>
<xs:documentation>Valid only if geospatial or civil location presented</xs:documentation>
</xs:annotation>
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="south"/>
<xs:enumeration value="north"/>
<xs:enumeration value="east"/>
<xs:enumeration value="west"/>
<xs:enumeration value="above"/>
<xs:enumeration value="below"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="same">
<xs:simpleType>
<xs:list itemType="WhereAttributes"/>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="difference">
<xs:simpleType>
<xs:list itemType="WhereAttributes"/>
</xs:simpleType>
</xs:attribute>
<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:complexType>
</xs:schema>
19.8 XML Schema for LESS Queue Handling Extension
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<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSPY v2004 rel. 2 U (http://www.xmlspy.com) by Xiaotao Wu (Columbia University Computer Science Dept) -->
<xs:schema targetNamespace="urn:ietf:params:xml:ns:less:queue" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:LESS="urn:ietf:params:xml:ns:less" xmlns="urn:ietf:params:xml:ns:less:queue" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:import namespace="urn:ietf:params:xml:ns:less" schemaLocation="less.xsd"/>
<xs:simpleType name="QueueName">
<xs:union>
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="callback"/>
<xs:enumeration value="hold"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:union>
</xs:simpleType>
<xs:complexType name="EnqueueActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="full" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
</xs:all>
<xs:attribute name="queue" type="QueueName" use="optional"/>
<xs:attribute name="maxlen" type="xs:positiveInteger" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="enqueue" type="EnqueueActionType" substitutionGroup="LESS:action"/>
<xs:complexType name="DequeueActionType">
<xs:complexContent>
<xs:extension base="LESS:ActionType">
<xs:all>
<xs:element name="success" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
<xs:element name="failure" minOccurs="0">
<xs:complexType>
<xs:group ref="Node"/>
</xs:complexType>
</xs:element>
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</xs:all>
<xs:attribute name="queue" type="QueueName" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="dequeue" type="DequeueActionType" substitutionGroup="LESS:action"/>
</xs:schema>
20 References
20.1 Normative References
[1] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," RFC 2119, Internet Engineering Task Force, Mar. 1997.
[2] J. Lennox, X. Wu, and H. Schulzrinne, "Call processing language
(CPL): a language for user control of Internet telephony services,"
rfc, Internet Engineering Task Force, Oct. 2004. Standard.
[3] T. Bray, J. Paoli, and C. M. Sperberg-McQueen, "Extensible markup
language (XML) 1.0 (second edition)," W3C Recommendation REC-xml-
20001006, World Wide Web Consortium (W3C), Oct. 2000. Available at
http://www.w3.org/XML/.
[4] D. C. Fallside, "XML schema part 0: Primer," W3C Candidate
Recommendation CR-xmlschema-0-20001024, World Wide Web Consortium
(W3C), Oct. 2000. Available at http://www.w3.org/TR/xmlschema-0/.
[5] H. Schulzrinne, "RPID -- rich presence information data format,"
Internet Draft draft-ietf-simple-rpid-01, Internet Engineering Task
Force, Feb. 2004. Work in progress.
[6] R. Moats, "URN syntax," RFC 2141, Internet Engineering Task
Force, May 1997.
[7] R. Moats, "A URN namespace for IETF documents," RFC 2648,
Internet Engineering Task Force, Aug. 1999.
[8] R. Mahy, "The ietf xml registry," RFC 3688, Internet Engineering
Task Force, Jan. 2004.
[9] M. Murata, S. S. Laurent, and D. Kohn, "XML media types," RFC
3023, Internet Engineering Task Force, Jan. 2001.
[10] T. Bray, D. Hollander, and A. Layman, "Namespaces in XML," W3C
Recommendation REC-xml-names-19900114, World Wide Web Consortium
(W3C), Jan. 1999. Available at http://www.w3.org/TR/REC-xml-names/.
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20.2 Informative References
[11] X. Wu and H. Schulzrinne, "Where should services reside in
Internet telephony systems?," in IP Telecom Services Workshop,
(Atlanta, Georgia), Sept. 2000.
[12] X. Wu and H. Schulzrinne, "Programmable end system services
using SIP," in Conference Record of the International Conference on
Communications (ICC), May 2003.
[13] R. Stansifer, Study of Programming Languages, vol. 1. Florida
Institute of Technology: Prentice Hall, 1994.
[14] A. D. Falkoff and K. E. Iverson, "The design of APL," SIGAPL APL
Quote Quad, vol. 6, no. 1, pp. 5--14, 1975.
[15] X. Wu and H. Schulzrinne, "Feature interactions in Internet
telephony end systems," tech. rep., Department of Computer Science,
Columbia University, Jan. 2004.
[16] International Telecommunication Union, "General recommendations
on telephone switching and signaling -- intelligent network:
Introduction to intelligent network capability set 1," Recommendation
Q.1211, International Telecommunication Union, Geneva, Switzerland,
Mar. 1993.
[17] AT&T, 5ESS Switch, The Premier Solution, Feature Handbook, Issue
4. AT&T, Sept. 1987.
[18] E. International, "Services for computer supported
telecommunications applications (CSTA) Phase III," Standard 269, Ecma
International, June 2004.
[19] J. Lennox, H. Schulzrinne, and T. L. Porta, "Implementing
intelligent network services with the session initiation protocol,"
Technical Report CUCS-002-99, Columbia University, New York, New
York, Jan. 1999.
[20] VoiceXML Forum, "Voicexml home page." http://www.voicexml.org/.
[21] R. Mahy, "A message summary and message waiting indication event
package for the session initiation protocol (SIP)," RFC 3842,
Internet Engineering Task Force, Aug. 2004.
Authors' Addresses
Xiaotao Wu
Dept. of Computer Science
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Columbia University
1214 Amsterdam Avenue, MC 0401
New York, NY 10027
USA
electronic mail: xiaotaow@cs.columbia.edu
Henning Schulzrinne
Dept. of Computer Science
Columbia University
1214 Amsterdam Avenue, MC 0401
New York, NY 10027
USA
electronic mail: schulzrinne@cs.columbia.edu
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