SIMPLE WG M. Lonnfors
Internet-Draft Nokia Research Center
Expires: November 18, 2003 J. Costa-Requena
E. Leppanen
H. Khartabil
Nokia
May 20, 2003
Partial Notification of Presence Information
draft-lonnfors-simple-partial-notify-01
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on November 18, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
A Presence service can have constraints for delivering presence
information to devices with low data processing capabilities, small
display, and limited battery power. Other limitations can be caused
by the interface between the terminal and the network, i.e. over
radio links with high latency and low bandwidth. This memo presents a
solution that aids in reducing the impact of those constrains and to
increase efficiency, by introducing a mechanism called partial
notification.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Introduction of the partial notification mechanism . . . . . 4
3.1 Normal presence server operation . . . . . . . . . . . . . . 4
3.2 Operation of the partial notification . . . . . . . . . . . 4
4. Client and server operations . . . . . . . . . . . . . . . . 5
4.1 Content-type for partial notifications . . . . . . . . . . . 5
4.2 Watcher generating SUBSCRIBE requests . . . . . . . . . . . 5
4.3 Notifier processing of SUBSCRIBE requests . . . . . . . . . 5
4.4 Notifier generating partial notifications . . . . . . . . . 6
4.5 Watcher processing of partial notifications . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . 8
5.1 URN sub-namespace registration for
'urn:ietf:params:xml:ns:pidf-partial' . . . . . . . . . . . 8
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1 Subscription with partial notification as optional . . . . . 9
6.2 Subscription with partial notification as requirement . . . 13
7. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 17
8. Security Considerations . . . . . . . . . . . . . . . . . . 19
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
10. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1 Changes since -00 . . . . . . . . . . . . . . . . . . . . . 20
Normative references . . . . . . . . . . . . . . . . . . . . 20
Informative references . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 21
Intellectual Property and Copyright Statements . . . . . . . 23
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1. Introduction
SIP extensions for presence [4] allow users ('watchers') to subscribe
to other users' ('presentities') presence information. The presence
information is composed of multiple pieces of data that are delivered
to the watcher. The size of the presence information document can be
large (i.e. the presence document can contain an arbitrary number of
elements called presence tuples that convey data). It may not be
reasonable to send the complete presence information over low
bandwidth and high latency links when only part of that information
changes. This may end up degrading the presence service and causing
bad perception at the watcher side.
Presence based applications in wireless terminals have certain
limitations because it is envisioned that the presence service may
demand high bandwidth. Requirements for wireless environments can be
found in [12].
There are some mechanisms, such as signaling compression [14] and
content indirection [11], [10] that might be used to help in this
problem. However, none of the existing solutions are optimal because
they set additional requirements on basic network functionalities
such as security. Some of the existing solutions enforce certain
requirements on the network and terminals for supporting compression
mechanism, while other solutions require having a specific server to
store the requested presence information until the terminal fetches
it using another protocol (HTTP) and therefore increases possible
security concerns.
This draft presents a solution to these problems, called Partial
Notifications. Requirements for this mechanism are presented in [3].
Other set of requirements can be found from [12]. The idea is already
identified by the SIP Extensions for Presence document [4] as a
potential solution.
In general, the partial notification approach means that the Presence
Server (PS) delivers to the watchers only those parts of the presence
information that have changed compared to the presence information
sent in the previous notification. Note that partial notification is
not IMPP compliant.
This document introduces a new MIME-Type 'application/pidf-
partial+xml' and a Require header extension 'partial-notification'.
2. Conventions
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
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and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
indicate requirement levels for compliant implementations.
3. Introduction of the partial notification mechanism
This chapter briefly introduces the current functionality of the
presence service, and gives an overview of the partial notification
solution and new items needed to implement it.
3.1 Normal presence server operation
The presence service normally operates so that the watcher sends the
SIP SUBSCRIBE request targeted to the presentity. The request is
routed up to the presence server responsible for terminating the
request. The SUBSCRIBE request MAY include an Accept header field for
indicating the supported content types [5]
The PS receives the SUBSCRIBE request and if there is no Accept
header indicating the supported content types, the PS will generate
the presence notification using the default PIDF format [6]. The PIDF
may contain one or multiple tuples and presence document level
information. The tuples include a set of elements defined in the
presence model [2] for representing the presence information. The
presence information is sent to the watcher in the body of the NOTIFY
request according to [7]. By default, the presence information
contains the full state corresponding to the presence status of the
presentity, as determinated by the PS local policy and authorization
rules.
3.2 Operation of the partial notification
The mechanism for implementing the partial notification consists of
defining a new content type. The new content type is named as
'application/pidf-partial+xml'. It is similar to PIDF [6] except that
it adds new XML items to <presence> element in order to enable the
partial notifications. The new XML attributes are "version" and
"state". The new XML element is "removed".
The "version" attribute is a sequence number that is progressively
incremented for each watcher when notification is sent. The "state"
attribute indicates the nature of the presence information included
in the notified document, whether it contains full or partial state
corresponding to the cases when the full presence information or only
changed parts of the presence information are delivered. The use of
these attributes is similar to the watcher information template
package [9].
In the scope of this document the partial updates apply only to
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<tuple> level XML elements and everything what is contained inside
these elements, in other words: tuples are considered to be atomic
data elements. This means the when an update is send to a tuple it is
assumed that the whole tuple is completely replaced by the new one.
All the data which is located outside the <tuple> elements must be
processed as specified in [4]. Usually this means that all those XML
elements (for example the <note> element) must be included in every
notification.
4. Client and server operations
This document assumes that unless otherwise specified in this
document the normal subscriber and notifier behavior is applied as
defined in [4]. The watcher has the same behavior as a subscriber.
4.1 Content-type for partial notifications
The entities supporting the partial notification extension described
in this document MUST support the 'application/pidf-partial+xml'
content-type.
4.2 Watcher generating SUBSCRIBE requests
The SUBSCRIBE request can be used to negotiate the preferred content
type to be used in the notifications. The Accept header is used for
this purpose as specified in [5]. When watcher wants to allow PS to
send partial notifications it MUST include Accept header value
'application/pidf-partial+xml' into SUBSCRIBE request.
OPEN ISSUE: The watcher MAY include the Require header with the value
'partial-notification' if the watcher wants to be sure that the PS
supports and uses the extensions defined in this specification.
4.3 Notifier processing of SUBSCRIBE requests
The Presence Server receives the subscriptions from the watchers and
generates the notifications according to [4]. If the watcher has
indicated the supported content types in the Accept header the
Presence Server compares the content types included in the Accept
header with the supported ones, and decide which one to use according
to its local policy.
OPEN ISSUE: The watcher MAY have included the Require header with the
value 'partial-notification'. If the PS does not support the
'partial-notification' extension, it rejects the request as defined
in [5]. If the PS supports the extension, it MUST use the
'application/pidf-partial+xml' content type in all subsequent NOTIFY
requests.
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4.4 Notifier generating partial notifications
If the content type negotiation between the watcher and the PS
resulted in the agreement to use partial notifications, then the PS
MUST use the 'application/pidf-partial+xml' content type in the
NOTIFY requests.
The PS MUST deliver the full state of the presence information
according to [4] in the first notification. In this case, the "state"
attribute of the <presence> element in the presence document MUST be
set to the value "full". The "version" attribute MUST also be present
and it MUST be initialized to value zero.
When the PS generates subsequent notifications, the presence document
includes only the tuples that have changed compared to the previous
notification. It is up to the local policy to determine what is
considered as a change to the previous state. The "state" attribute's
value MUST be set to "partial".
The PS constructs the presence document according to the following
logic:
o The delivered presence information is constructed according to [4]
in such a way that only the changed tuples are delivered. New
tuples are also be added to the presence information, if any.
o The "version" and "state" attributes are also included in the
presence document. The version number is incremented by one
compared to the earlier delivered presence document to the watcher
associated with a certain subscription. The version number should
follow the COUNTER32 format so that after reaching the maximum
value it starts from zero [15].
o When there are changes (e.g. in the authorization) which lead to
removal of tuples from the previously delivered presence
information the PS lists the IDs of the removed tuples in the
"removed" element.
o All the presence information outside the <tuple> elements MUST be
included in each notification, i.e., all the notifications which
convey partial notifications MUST always have that data.
4.5 Watcher processing of partial notifications
If the negotiation between the watcher and the PS resulted in the
agreement to use the partial notifications, then the watcher receives
'application/pidf-partial+xml' content type in the subsequent NOTIFY
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requests.
The watcher receives the full state of the presence information
according to [4] in the first notification. In this case, the "state"
element of the presence document has the value "full". When the
watcher receives the full state notification it MUST perform the
following actions:
o The watcher MUST discard all previously received presence
information from that particular presentity.
o The watcher MUST initialize an internal version counter, related
that particular presentity or subscription, to the value received
in the notification.
o The watcher MUST store the values of all tuple IDs together with
the content received in the notification.
When the watcher receives subsequent notifications, the presence
document includes only those tuples that have changed compared to the
previous notification. The "state" element includes the value of
"partial" telling to the watcher that the notification includes
partial information. The watcher MUST construct the presence
information according to the following logic:
o The "version" attribute of the <presence> element is compared with
the version information in the previously received presence
document. If the version number is incremented by one, the watcher
continues handling the content present in the notification.
o The Watcher compares tuple IDs to the tuple IDs received in the
previous notifications. If a tuple ID in the notification matches
an existing tuple ID, the existing tuple is replaced with the
newly received in the notification. If the tuple ID does not match
to those received in the earlier notifications, it is stored as
new tuple.
o If the presence document includes the "removed" element the tuples
which IDs are listed are removed from the local storage.
o Tuples whose IDs are missing in the NOTIFY remain unchanged.
In case the watcher receives a partial notification with the
"version" attribute value higher than the stored value by more than
one, the watcher assumes that one or more NOTIFY were lost and SHOULD
either refresh the subscription within the existing dialog in order
to receive a complete update (full state) of the presence information
or terminate the subscription. If the watcher receives a notification
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with "state" attribute value "partial" and the "version" attribute
value equal or smaller than the one in the previous notification, it
is considered a PS failure and the watcher SHOULD either refresh or
terminate the subscription.
All information received in the notification which is located outside
the <tuple> element must be processed as specified in [4]. I.e., the
watcher must replace the existing data with data received in the
latest notification.
OPEN ISSUE: It is possible that the PS changes the content type used
in notifications within existing dialog. If this happens watcher must
discard all state related to 'application/PIDF-partial+xml' and
process new MIME type as specified by that MIME type.
5. IANA Considerations
This memo calls for IANA to register a new XML namespace URN per [8].
A new content type 'application/pidf-partial+xml' is defined to
represent an XML MIME for the partial presence information content.
This specification follows the guidelines of RFC3023 [13].
OPEN ISSUE: IANA registration may be needed for the value
'partial-notification' of the Require header as a SIP extension.
5.1 URN sub-namespace registration for
'urn:ietf:params:xml:ns:pidf-partial'
URI:
uurn:ietf:params:xml:ns:pidf-partial
Description:
This is the XML namespace for XML elements defined by [[[RFCXXXX]]]
to describe the 'application/pidf-partial+xml' content type for
partial notifications.
Registrant Contact:
IETF, SIMPLE working group, <simple@ietf.org>
Mikko Lonnfors, <mikko.lonnfors@nokia.com>
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>PIDF extension for partial notifications</title>
</head>
<body>
<h1>Namespace for PIDF extension for partial
notifications</h1>
<h2>application/pidf-partial+xml</h2>
<p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
6. Examples
The following message flows show examples applying the partial
notifications mechanism. The document of the 'application/
pidf-partial+xml' format mentioned in the message details is
constructed according to the XML schema described in the chapter
Section 7.
6.1 Subscription with partial notification as optional
The watcher sends a SUBSCRIBE request including the default presence
format (PIDF) and the content type for the partial notification in
the Accept header field. The PS accepts the subscription and based on
a local policy it selects to send partial notifications in NOTIFY
requests according to the logic described in this document. The first
NOTIFY request includes the full state of presence information
represented in the 'application/pidf-partial+xml' content type. The
following notifications only include the delta of the presence
information from the previous NOTIFY request.
Watcher Presence Server PUA
| F1 SUBSCRIBE | |
|-------------------------->| |
| F2 200 OK | |
|<--------------------------| |
| F3 NOTIFY | |
|<--------------------------| |
| F4 200 OK | |
|-------------------------->| |
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| | |
| | Update presence |
| |<----------------------- |
| | |
| F5 NOTIFY | |
|<--------------------------| |
| F6 200 OK | |
|-------------------------->| |
Message Details
F1 SUBSCRIBE watcher->example.com server
SUBSCRIBE sip:resource@example.com SIP/2.0
Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
To: sip:resource@example.com
From: sip:watcher@somewhere.com ;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17766 SUBSCRIBE
Max-Forwards: 70
Event: presence
Accept: application/cpim-pidf+xml, application/pidf-partial+xml
Contact: user@watcherhost.example.com
Expires: 600
Content-Length: 0
F2 200 OK example.com server->watcher
The Presence Server accepts the subscription and based on the local
policy it applies the partial notitifcations. (See that the value
'application/pidf-partial+xml' in the Content-Type header).
SIP/2.0 200 OK
Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
;received=192.0.2.1
To: sip:resource@example.com;tag=ffd2
From: sip:watcher@somewhere.com;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17766 SUBSCRIBE
Event: presence
Expires: 600
Contact: sip:server.example.com
Content-Length: 0
F3 NOTIFY example.com server-> watcher
NOTIFY sip:user@watcherhost.example.com SIP/2.0
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Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
Event: presence
Subscription-State: active;expires=599
Max-Forwards: 70
CSeq: 8775 NOTIFY
Contact: sip:server.example.com
Content-Type: application/pidf-partial+xml
Content-Length: ..
PIDF-PARTIAL+XML Document with FULL STATE information:
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:pidf-partial"
entity="pres:someone@example.com" version="1" state="full">
<impp:tuple id="sg89ae">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="0.8">tel:09012345678</impp:contact>
</impp:tuple>
<impp:tuple id="cg231jcr">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="1.0">
im:pep@example.com</impp:contact>
</impp:tuple>
<impp:tuple id="r1230d">
<impp:status><impp:basic>closed</impp:basic></impp:status>
<impp:contact priority="0.9">
sip:pep@example.com</impp:contact>
</impp:tuple>
</impp:presence>
F4 200 OK watcher-> example.com server
SIP/2.0 200 OK
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
;received=192.0.2.2
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
CSeq: 8775 NOTIFY
Content-Length: 0
F5 NOTIFY example.com server -> watcher
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It is the local policy issue to construct the 'PIDF-partial+xml'
formated document including the delta from the previous NOTIFY.
Note that the tuple which id was "r1230d" was deleted.
NOTIFY sip:user@watcherhost.example.com SIP/2.0
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sl
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
CSeq: 8776 NOTIFY
Event: presence
Subscription-State: active;expires=543
Max-Forwards: 70
Contact: sip:server.example.com
Content-Type: application/pidf-partial+xml
Content-Length: ...
New PIDF-PARTIAL+XML Document with PARTIAL STATE information:
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:pidf-partial"
entity="pres:someone@example.com" version="2" state="partial">
<impp:removed><impp:t_id>r1230d</impp:t_id></impp:removed>
<impp:tuple id="cg231jcr">
<impp:status><impp:basic>closed</impp:basic></impp:status>
<impp:contact priority="1.0">
im:pep@examploe.com</impp:contact>
<impp:notexml:lang="en">This is an update of existing tuple
sent in previous notification</note>
</impp:tuple>
<impp:tuple id="wsqw798jcr">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="0.4">
im:mac@hut.com</impp:contact>
<impp:note xml:lang="en">This is a completely new tuple not
sent in previous notification</note>
</impp:tuple>
</impp:presence>
F6 200 OK watcher-> example.com server
SIP/2.0 200 OK
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sl
;received=192.0.2.2
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
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Call-ID: 2010@watcherhost.example.com
CSeq: 8776 NOTIFY
Content-Length: 0
6.2 Subscription with partial notification as requirement
The watcher sends SUBSCRIBE request including the
'partial-notification' extension in the Require header field. The PS
does not support the extension, so it rejects the subscription. The
watcher re-subscribed without including the Require header.
Watcher Presence Server PUA
| F1 SUBSCRIBE | |
|-------------------------->| |
| F2 420 Bad Extension | |
|<--------------------------| |
| F3 SUBSCRIBE | |
|-------------------------->| |
| F4 200 OK | |
|<--------------------------| |
| F5 NOTIFY | |
|<--------------------------| |
| F6 200 OK | |
|-------------------------->| |
| | |
| | Update presence |
| |<----------------------- |
| | |
| F7 NOTIFY | |
|<--------------------------| |
| F8 200 OK | |
|-------------------------->| |
Message Details:
F1 SUBSCRIBE watcher->example.com server
SUBSCRIBE sip:resource@example.com SIP/2.0
Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
To: sip:resource@example.com
From: sip:watcher@somewhere.com;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17766 SUBSCRIBE
Max-Forwards: 70
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Event: presence
Require: partial-notification
Contact: sip:user@watcherhost.example.com
Expires: 600
Content-Length: 0
F2 420 Bad Extension example.com server->watcher
The Presence Server does not support the extension indicated in the
Require header and the subscription is rejected.
SIP/2.0 420 OK
Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
;received=192.0.2.1
To: sip:resource@example.com
From: sip:watcher@somewhere.com;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17766 SUBSCRIBE
Event: presence
Expires: 600
Unsupported: partial-notification
Contact: sip:server.example.com
Content-Length: 0
F3 SUBSCRIBE watcher -> example.com server
The watcher makes subscribtion without any requirements for the partial
notifications. The default presence service and PDIF format are applied.
SUBSCRIBE sip:resource@example.com SIP/2.0
Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
To: sip:resource@example.com
From: sip:watcher@somewhere.com;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17767 SUBSCRIBE
Max-Forwards: 70
Event: presence
Contact: sip:user@watcherhost.example.com
Expires: 600
Content-Length: 0
F4 200 OK example.com server->watcher
SIP/2.0 200 OK
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Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
;received=192.0.2.1
To: sip:resource@example.com
From: sip:watcher@somewhere.com;tag=xfg9
Call-ID: 2010@watcherhost.example.com
CSeq: 17767 SUBSCRIBE
Event: presence
Expires: 600
Contact: sip:server.example.com
Content-Length: 0
F5 NOTIFY example.com server -> watcher
NOTIFY sip:user@watcherhost.example.com SIP/2.0
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
Event: presence
Subscription-State: active;expires=599
Max-Forwards: 70
CSeq: 8775 NOTIFY
Contact: sip:server.example.com
Content-Type: application/cpim-pidf+xml
Content-Length: ..
CPIM-PIDF+XML formatted document:
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:cpim-pidf"
entity="pres:someone@example.com">
<impp:tuple id="sg89ae">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="0.8">tel:09012345678</impp:contact>
</impp:tuple>
<impp:tuple id="cg231jcr">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="1.0">
im:pep@example.com</impp:contact>
</impp:tuple>
</impp:presence>
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F6 200 OK watcher-> example.com server
SIP/2.0 200 OK
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
;received=192.0.2.2
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
CSeq: 8775 NOTIFY
Content-Length: 0
F7 NOTIFY example.com server -> watcher
NOTIFY sip:user@watcherhost.example.com SIP/2.0
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sl
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
CSeq: 8776 NOTIFY
Event: presence
Subscription-State: active;expires=543
Max-Forwards: 70
Contact: sip:server.example.com
Content-Type: application/cpim-pidf+xml
Content-Length: ...
New CPIM-PIDF+XML formatted_document:
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:cpim-pidf"
entity="pres:someone@example.com">
<impp:tuple id="sg89ae">
<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="0.8">tel:09012345678</impp:contact>
</impp:tuple>
<impp:tuple id="cg231jcr">
<impp:status><impp:basic>closed</impp:basic></impp:status>
<impp:contact priority="1.0">
im:pep@example.com</impp:contact>
<impp:note xml:lang="en">This is an update of existing
tuple sent in previous notification</note>
</impp:tuple>
<impp:tuple id="wsqw798jcr">
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<impp:status><impp:basic>open</impp:basic></impp:status>
<impp:contact priority="0.4">
im:mac@hut.com</impp:contact>
<impp:note xml:lang="en">This is a completely new tuple not
sent in previous notification</note>
</impp:tuple>
</impp:presence>
F8 200 OK
SIP/2.0 200 OK
Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sl
;received=192.0.2.2
To: sip:watcher@somewhere.com;tag=xfg9
From: sip:resource@example.com;tag=ffd2
Call-ID: 2010@watcherhost.example.com
CSeq: 8776 NOTIFY
Content-Length: 0
7. XML Schema
The XML schema for the 'pidf-partial+xml' data format.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:ietf:params:xml:ns:pidf-partial"
xmlns:tns="urn:ietf:params:xml:ns:pidf-partial"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<!-- This import brings in the XML language attribute xml:lang-->
<xs:import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2001/xml.xsd"/>
<xs:element name="presence" type="tns:presence"/>
<xs:complexType name="presence">
<xs:sequence>
<xs:element name="tuple" type="tns:tuple"
maxOccurs="unbounded"/>
<xs:element name="note" type="tns:note" minOccurs="0"
maxOccurs="unbounded"/>
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<xs:element name="removed" type="tns:removed_tuple" minOccurs="0"
maxOccurs="1"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="entity" type="xs:anyURI" use="required"/>
<xs:attribute name="version" type="xs:nonNegativeInteger"
use="required"/>
<xs:attribute name="state" use="required">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="full"/>
<xs:enumeration value="partial"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
<xs:complexType name="tuple">
<xs:sequence>
<xs:element name="status" type="tns:status"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
<xs:element name="contact" type="tns:contact" minOccurs="0"/>
<xs:element name="note" type="tns:note" minOccurs="0"
maxOccurs="unbounded"/>
<xs:element name="timestamp" type="xs:dateTime" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="id" type="xs:ID" use="required"/>
</xs:complexType>
<xs:complexType name="status">
<xs:sequence>
<xs:element name="basic" type="tns:basic" minOccurs="0"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="basic">
<xs:restriction base="xs:string">
<xs:enumeration value="open"/>
<xs:enumeration value="closed"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="contact">
<xs:simpleContent>
<xs:extension base="xs:anyURI">
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<xs:attribute name="priority" type="tns:qvalue"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="note">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute ref="xml:lang"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:simpleType name="qvalue">
<xs:restriction base="xs:decimal">
<xs:pattern value="0(.[0-9]{0,3})?"/>
<xs:pattern value="1(.0{0,3})?"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="removed_tuple">
<xs:sequence>
<xs:element name="t_id" type="xs:ID" minOccurs="1"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<!-- Global Attributes -->
<xs:attribute name="mustUnderstand" type="xs:boolean" default="0">
<xs:annotation>
<xs:documentation>
This attribute may be used on any element within an optional
PIDF extension to indicate that the corresponding element must
be understood by the PIDF processor if the enclosing optional
element is to be handled.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:schema>
8. Security Considerations
Presence information may contain highly sensitive information about
the presentities. Presence related security considerations are
extensively discussed in [4] and all those identified security
consideration apply to this document as well. Partial notification
mechanism does not add anything new which (in term of the security)
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is not already specified in [4] and [5]. Thus no new security
considerations are introduced here.
9. Acknowledgements
The authors would like to thank Jyrki Aarnos, Jonathan Rosenberg,
Dean Willis, Kriztian Kiss, Juha Kalliokulju and Tim Moran for their
valuable comments.
10. Changes
10.1 Changes since -00
o Section comparing the existing mechanisms removed.
o Solution on the removal of the tuple changed. Texts, XML Schema
and examples modified accordinly.
o Reduntant texts and issues specified in other specifications
removed.
o Other editorial changes, e.g., more normative style, references
devided into Informal and Normative.
Normative references
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
Instant Messaging", RFC 2778, February 2000.
[3] Lonnfors, M., Leppanen, E., Requena, J. and H. Khartabil,
"Requirements for Efficient Delivery of Presence Information",
draft-ietf-simple-presinfo-deliv-reg-00 (work in progress),
April 2003.
[4] Rosenberg, J., "SIP Extensions for Presence",
draft-ietf-simple-presence-10 (work in progress), January 2003.
[5] Rosenberg, J., "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[6] Sugano, H., "CPIM presence information data format",
draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003.
[7] Roach, A., "SIP-Specific Event Notification", RFC 3265, June
2002.
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Informative references
[8] Mealling, M., "The IETF XML Registry",
draft-mealling-iana-xmlns-registry-04 (work in progress), June
2002.
[9] Rosenberg, J., "A Watcher Information Event Template-Package
for the Session Initiation Protocol (SIP)",
draft-ietf-simple-winfo-package-05 (work in progress), January
2003.
[10] Khartabil, H., "Congestion safety and Content Indirection",
draft-khartabil-sip-congestionsafe-ci-02 (work in progress),
March 2003.
[11] Olson, S., "Mechanism for Content Indirection in Session
Initiation Protocol (SIP) Messages",
draft-ietf-sip-content-indirect-mech-02 (work in progress),
February 2003.
[12] Kiss, K., "Requirements for Presence Service based on 3GPP
specifications and wireless environment characheristics",
draft-kiss-simple-presence-wireless-reqs-01 (work in progress),
February 2003.
[13] Murata, M., "XML media types", RFC 3023, January 2001.
[14] Price, R., "Signaling Compression (SigComp)", RFC 3320, January
2003.
[15] McCloghrie, K., "Structure of Management Information Version 2
(SMIv2)", RFC 2578, April 1999.
Authors' Addresses
Mikko Lonnfors
Nokia Research Center
Itamerenkatu 11-13 00180
Helsinki
Finland
Phone: +358 50 4836402
EMail: mikko.lonnfors@nokia.com
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Jose Costa-Requena
Nokia
Valimotie 9 00380
Helsinki
Finland
Phone: +358 71 8008000
EMail: jose.costa-requena@nokia.com
Eva Leppanen
Nokia
P.O BOX 785
Tampere
Finland
Phone: +358 7180 77066
EMail: eva-maria.leppanen@nokia.com
Hisham Khartabil
Nokia
P.O. Box 321
Helsinki
Finland
Phone: +358 7180 76161
EMail: hisham.khartabil@nokia.com
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