Network Working Group H. Sugano
INTERNET-DRAFT S. Fujimoto
Fujitsu
G. Klyne
Baltimore Technologies
A. Bateman
VisionTech
W. Carr
Intel
Expires: November 2002 May 2002
Common Presence and Instant Messaging (CPIM)
Presence Information Data Format
<draft-ietf-impp-cpim-pidf-05.txt>
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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Please send comments to the authors or to the impp@iastate.edu
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Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This memo specifies the Common Presence and Instant Messaging (CPIM)
Presence Information Data Format (PIDF) as a common presence data
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format for CPIM-compliant Instant Messaging and Presence protocols,
and also defines a new media type "application/cpim-pidf+xml" to
represent the XML MIME entity for PIDF.
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Table of Content
1. Introduction ......................................... 4
1.1. Terminology and Conventions .......................... 4
2. Design Decisions ..................................... 5
2.1. Minimal Model ........................................ 5
2.2. Added Features ....................................... 6
2.3. XML Encoding Decision ................................ 6
3. Overview of Presence Information Data Format ......... 6
3.1. The 'application/cpim-pidf+xml' Content Type ......... 7
3.2. Presence Information Contents ........................ 7
4. XML-encoded Presence Data Format ..................... 7
4.1. XML Format Definitions ............................... 7
4.1.1. The <presence> element ............................... 8
4.1.2. The <tuple> element .................................. 8
4.1.3. The <status> element ................................. 9
4.1.4. The <basic> element .................................. 9
4.1.5. The <contact> element ................................ 9
4.1.6. The <note> element ................................... 10
4.1.7. The <timestamp> element .............................. 10
4.2. Presence Information Extensibility ................... 10
4.2.1. XML Namespaces Background ............................ 10
4.2.2. XML Namespaces In Presence Information ............... 11
4.2.3. Handling Of Unrecognized Element Names ............... 12
4.2.4. Status Value Extensibility ........................... 13
4.3. Examples ............................................. 13
4.3.1. Default Namespace with Status Extensions ............. 13
4.3.2. Presence with Other Extension Elements ............... 14
4.3.3. Example Mandatory To Understand Extensions ........... 15
4.4. XML Schema Definitions ............................... 15
5. IANA Considerations .................................. 17
5.1. Content-type registration for 'application/cpim-pidf+xml'
.................................................. 17
5.2. URN sub-namespace registration for
'urn:ietf:params:xml:ns:cpim-pidf' ............... 18
6. Security Considerations .............................. 19
7. Internationalization Considerations .................. 19
8. Normative References ................................. 20
9. Informative References ............................... 21
10. Authors' Addresses .................................. 21
11. Appendix A. Document Type Definitions ............... 22
12. Full Copyright Statement ............................ 23
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1. Introduction
The Common Profile for Instant Messaging (CPIM) specifications define
a set of common operations and various formats to achieve
interoperability between different Instant Messaging and Presence
protocols which meet RFC 2779 [RFC2779]. The CPIM core specification
[CPIM] defines a set of common operations and their parameters to be
supported by interworking Presence and IM protocols in order to allow
straightforward gatewaying between them. The work on CPIM Message
Format [CPIM-MSG] defines a common format for instant messages, which
enables secure end-to-end IM exchange through the gateways.
This memo further defines the CPIM Presence Information Data Format
(PIDF) as a common presence data format for CPIM-compliant presence
protocols. The significance of the common presence format primarily
resides in the fact that it alleviates the load of gatewaying of
messages with presence data payloads. Without such a common presence
data format, a gateway must process and transform the presence data
payload from one format to another every time it gateways the
protocol messages. Such payload processing also disables the
validity of digitally signed presence data. Utilizing the common
presence data format allows secure transfer of the presence payloads
across the boundary of different protocol domains.
The format specified in this memo is intended to define the base
presence format and extensibility required by RFC 2779. It only
defines a minimal set of presence status values defined by the IMPP
Model document [RFC2778]. However, a presence application is able to
define its own status values using the extensibility framework
provided by this memo. Defining such extended status values is
beyond the scope of this memo.
Note also that this memo only defines the format for a presence data
payload only and how the presence data is transferred within a
specific protocol frame would be defined in actual protocol
specifications.
1.1. Terminology and Conventions
This memo makes use of the vocabulary defined in the IMPP Model
document [RFC2778]. Terms such as CLOSED, INSTANT MESSAGE, OPEN,
PRESENCE SERVICE, PRESENTITY, WATCHER, and WATCHER USER AGENT in the
memo are used in the same meaning as defined therein.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in RFC 2119 [RFC2119].
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[[[Editorial comments and questions about outstanding issues are
provided in triple brackets like this. These working comments should
be resolved and removed prior to final publication.]]]
2. Design Decisions
We have adopted the IMPP Model and Requirements documents [RFC2778,
RFC2779] as the starting point of our discussion. The two RFCs
contains a number of statements about presence information, which can
be regarded as a basic set of constraints for the format design.
Also, we took the minimalist approach to the design based on them.
Starting from the minimal model, only the features that are necessary
to solve particular problems have been combined.
2.1. Minimal Model
This specification is based on the minimal model extracted from the
IMPP Model and Requirements documents. The model consists of the
following items. Each of them is accompanied with the corresponding
RFCs and their section numbers as its grounds, e.g. (RFC2778:Sec.2.4)
refers to Section 2.4 of RFC 2778.
(a) PRESENCE INFORMATION consists of one or more PRESENCE TUPLES,
where a PRESENCE TUPLE consists of a STATUS, an optional
COMMUNICATION ADDRESS, and optional OTHER PRESENCE MARKUP.
(RFC2778:Sec.3)
(b) STATUS has at least the mutually-exclusive values OPEN and
CLOSED, which have meaning for the acceptance of INSTANT
MESSAGES, and may have meaning for other COMMUNICATION MEANS.
There may be other values of STATUS that do not imply anything
about INSTANT MESSAGE acceptance. These other values of STATUS
may be combined with OPEN and CLOSED or they may be mutually-
exclusive with those values. (RFC2778:Sec.3, RFC2779:Sec.4.4.1-
4.4.3)
(c) STATUS may consist of single or multiple values. (RFC2778:Sec.2.4)
(d) There must be a means of extending the common presence format
to represent additional information not included in the common
format. The extension and registration mechanisms must be
defined for presence information schema, including new STATUS
conditions and new forms for OTHER PRESENCE MARKUP. (RFC2779:
Sec.3.1.4-3.1.5)
(e) The common presence format must include a means to uniquely
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identify the PRESENTITY whose PRESENCE INFORMATION is reported.
(RFC2779:Sec.3.1.2)
(f) The common presence format must allow the source of the presence
data (i.e. PRESENTITY) to utilize some security mechanism (e.g.
digital signature or encryption) for the secure transportation
of the data. (RFC2779:Sec.5.2.1, 5.3.1, 5.3.3)
(g) The common presence format must be extensible to represent
additional information not defined in this memo. (RFC2779:
Sec.3.1.4)
2.2. Added Features
In addition to the minimal model described above, the format
specified in this specification has the following features.
(a) Relative priorities of contact addresses should be specifiable
in order to allow the source of PRESENCE INFORMATION to tell the
receiver (WATCHER USER AGENTS) its preference over multiple contact
means.
(b) The presence format should be able to contain the timestamp of
the creation of the PRESENCE INFORMATION. The timestamp in the
presence document lets the receiver know the time of the creation
of the data even if the message containing it arrives late for
some reason. It can also be used to detect a replay attack,
independent of the underlying signature mechanism.
2.3. XML Encoding Decision
The CPIM Presence Information Data Format encodes presence
information in XML (eXtensible Markup Language [XML]), which is
rapidly gaining broad acceptance as a syntactic framework to encode
structured data transferred over the Internet. Regarding the
features of PRESENCE INFORMATION discussed above, such that it has a
hierarchical structure and it should be fully extensible, XML is
considered as the most desirable framework over other candidates such
as vCard [RFC2426].
3. Overview of Presence Information Data Format
This section describes an overview of the presence data format
defined in this memo.
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3.1. The 'application/cpim-pidf+xml' Content Type
This memo defines a new content type "application/cpim-pidf+xml" to
represent an XML MIME entity which encodes a presence information
document conformant to this specification. Because the new content
type is XML-based, this specification follows the recommendations and
conventions described in [RFC3023], including the naming convention
of the type ('+xml' suffix) and the usage of the 'charset' parameter.
As for the 'charset' parameter, although it is defined as optional,
the use of that parameter is STRONGLY RECOMMENDED. If the 'charset'
parameter is not specified, conforming XML processors to [XML] MUST
follow the requirements in section 4.3.3 of [XML].
3.2. Presence Information Contents
This subsection outlines types of information included in an
"application/cpim-pidf+xml" type document. The real definition of the
content type will be presented in Section 4.
o PRESENTITY URL: specifies the "pres" URL of the PRESENTITY.
o List of presence tuples
- Status: OPEN/CLOSED for Instant Messaging or status for
other communication means.
- Communication address: communication means and contact
address of this tuple. (optional)
- Relative priority: numerical value specifying the priority
of this communication address. (optional)
- Timestamp: timestamp of the change of this tuple.(optional)
- Human readable comment: free text memo about this tuple
(optional)
o PRESENTITY human readable comment: free text memo about the
PRESENTITY (optional).
4. XML-encoded Presence Data Format
This section defines an XML-encoded presence data format of the
content type "application/cpim-pidf+xml" for presence payloads. A
presence payload of this type is expected to be produced by the
PRESENTITY (the source of the PRESENCE INFORMATION) and transported
to the WATCHERS by the presence servers or gateways without any
interpretation or modification.
4.1. XML Format Definitions
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An "application/cpim-pidf+xml" object is a well formed XML document.
It MUST have the XML declaration and it SHOULD contain an encoding
declaration in the XML declaration, e.g. "<?XML version='1.0'
encoding='UTF-8'?>". If the charset parameter of the MIME content
type declaration is present and it is different from the encoding
declaration, the charset parameter takes precedence.
4.1.1. The <presence> element
The root element of the "application/cpim-pidf+xml" object is defined
as <presence>. This element contains one or more <tuple> elements,
followed by any number (including 0) of OPTIONAL <note> elements,
followed by any number of OPTIONAL extension elements from other
namespaces.
The <presence> element MUST have an 'entity' attribute. The value of
the 'entity' attribute is the 'pres' URL of the PRESENTITY publishing
this presence document.
The <presence> element MUST contain a namespace declaration ('xmlns')
to indicate the namespace on which the presence document is based.
The presence document compliant to this specification MUST have the
namespace 'urn:ietf:params:xml:ns:cpim-pidf:'.
It MAY contain other namespace declarations for the extensions used
in the presence XML document.
4.1.2. The <tuple> element
The <tuple> element is used to carry a piece of PRESENCE INFORMATION
defined as PRESENCE TUPLE in RFC2778. Thus, it contains one
mandatory <status> element, followed by any number of OPTIONAL
extension elements from other namespaces, followed by one OPTIONAL
<contact> elements, followed by any number of OPTIONAL <note>
elements, followed by one OPTIONAL <timestamp> elements.
The <tuple> element MUST contain an 'id' attribute which is used to
distinguish this tuple from other tuples in the same XML document.
The value of an 'id' attribute MUST be unique within 'id' attribute
values of other tuples in the same document. An 'id' value is used
by applications processing the presence document to identify the
corresponding tuple in the previously acquired PRESENCE INFORMATION
of the same PRESENTITY. The value of the 'id' attribute SHOULD be
treated as just a CDATA value (no semantics).
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The <contact> element is OPTIONAL because a PRESENTITY might need to
hide its communication address or there might be tuples not related
to any communication means.
4.1.3. The <status> element
The <status> element contains one OPTIONAL <basic> elements, followed
by any number of OPTIONAL extension elements from other namespaces,
under the restriction that at least one child element appears in the
<status> element. These children elements of <status> contain status
values of this tuple. By allowing multiple status values in a single
<tuple> element, different types of status values, e.g. reachability
and location, can be represented by a <tuple>. See Section 4.3 for an
example with multiple status values.
This memo only defines the <basic> status value element. Other status
values may be included using the standard extensibility framework
(see Section 4.2.4). Applications encountering unrecognized elements
within <status> may ignore them, unless they carry a
mustUnderstand="true" or mustUnderstand="1" attribute (see section
4.2.3).
Note that, while the <status> element MUST have at least one status
value element, this status value may not be the <basic> element.
4.1.4. The <basic> element
The <basic> element contains one of the following strings: "open" or
"closed". The values "open" and "closed" has the same meaning as
OPEN and CLOSED defined in RFC 2778 respectively, and stand for
availability of receiving instant messages if the <tuple> is for an
instant messaging address. They also have meanings of general
availability for other communication means. But, this memo does not
specify them in detail.
4.1.5. The <contact> element
The <contact> element contains a URL of the contact address. It
optionally has a 'priority' attribute, whose value means a relative
priority of this contact address over the others. The value of the
attribute MUST be a decimal number between 0 and 1 inclusive with at
most 3 digits after the decimal point. Higher values indicate higher
priority. Examples of priority values are 0, 0.021, 0.5, 1.00. If the
'priority' attribute is omitted, applications MUST understand that
the contact address has the lowest priority. If the 'priority' value
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is out of the range, applications just SHOULD ignore the value and
process it as if the attribute was not present.
It is RECOMMENDED that applications handles a tuple with higher
priority than another one so that the priority is recognizable by
users. How to handle tuples with the same priority is up to
implementations.
4.1.6. The <note> element
The <note> element contains a string value, which is usually used for
a human readable comment. A <note> element MAY appear as a child
element of <presence> or as a child element of the <tuple> element.
In the former case, the comment is about the PRESENTITY and, in the
latter case, the comment is regarding the particular tuple.
The <note> element SHOULD have a special attribute 'xml:lang' to
specify the language used in the contents of this element as defined
in Section 2.12 of [XML]. The value of this attribute is the
language indentifier as defined by [RFC 1766]. It MAY be omitted when
the language used is implied by the larger context such as the
encoding information of the contents, e.g. the 'Shift_JIS' encoding
imples the language 'ja'.
4.1.7. The <timestamp> element
The <timestamp> element contains a string indicating the date and
time of the status change of this tuple. The value of this element
MUST follow the IMPP datetime format [DateTime].
While the IMPP datetime format allows use of either 'z' or 'Z' and
also 't' or 'T', XML Schema's dateTime requires using only 'T' and
'Z'. Timestamps that contain 'T' or 'Z' MUST use the capitalized
forms [XMLSchema2].
4.2. Presence Information Extensibility
The presence information extensibility framework is based on XML
namespaces [XML-NS].
4.2.1. XML Namespaces Background
All elements and some attributes are associated with a "namespace",
which is in turn associated with a globally unique URI. Any
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developer can introduce their own element names, avoiding conflict by
choosing an appropriate namespace URI.
Within the presence data, element or attribute names are associated
with a particular namespace by a namespace prefix, which is a leading
part of the name, followed by a colon (":"); e.g.
<prefix:element-name ...> ... </prefix:element-name>
Where, 'prefix' is the header name prefix, 'element-name' is a name
which is scoped by the namespace associated with 'prefix'. Note that
the choice of 'prefix' is quite arbitrary; it is the corresponding
URI that defines the naming scope. Two different prefixes associated
with the same namespace URI refer to the same namespace.
A default namespace can be declared for XML elements without a
namespace prefix. The default namespace does NOT apply to attribute
names, but interpretation of an unprefixed attribute can be
determined by the containing element.
A namespace is identified by a URI. In this usage, the URI is used
simply as a globally unique identifier, and there is no requirement
that it can be used to retrieve a web resource, or for any other
purpose. Any legal globally unique URI MAY be used to identify a
namespace. (By "globally unique", we mean constructed according to
some set of rules so that it is reasonable to expect that nobody else
will use the same URI for a different purpose.)
For further details, see the XML namespace specification [XML-NS].
4.2.2. XML Namespaces In Presence Information
A URI used as a namespace identifier in PRESENCE INFORMATION data
MUST be a full absolute-URI, per RFC 2396 [URI]. (Relative URIs and
URI- references containing fragment identifiers MUST NOT be used for
this purpose.)
The namespace URI for elements defined by this specification is a URN
[URN], using the namespace identifier 'ietf' defined by [URN-NS-IETF]
and extended by [XML-Registry]:
urn:ietf:params:xml:ns:cpim-pidf
Thus, simple presence data might be thus:
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:cpim-pidf"
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entity="pres:someone@example.com">
<impp:tuple id="mobile-phone">
<impp:status>
<impp:basic>open</impp:basic>
</impp:status>
<impp:contact priority="0.8">tel:09012345678</impp:contact>
</impp:tuple>
</impp:presence>
or, using a default XML namespace:
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
entity="pres:someone@example.com">
<tuple id="mobile-phone">
<status>
<basic>open</basic>
</status>
<contact priority="0.8">tel:09012345678</contact>
</tuple>
</presence>
As is generally the case in XML, the xmlns attribute can be used on
any element in the presence information to define either the default
namespace or a namespace associated with a namespace prefix.
4.2.3. Handling Of Unrecognized Element Names
Except as noted below, a processor of PRESENCE INFORMATION MUST
ignore any XML element with an unrecognized name (i.e. having an
unrecognized namespace URI, or an unrecognized local name within that
namespace). This includes all of the element content, even if it
appears to use recognized names.
It may be that some extensions must be understood in order for the
presence information to be properly understood. In such cases, the
element name is qualified with a mustUnderstand='true' or
mustUnderstand='1' attribute, which attribute name is associated with
the CPIM presence namespace.
NOTE: a mustUnderstand='true' or mustUnderstand='1' attribute
within an element that is being ignored is itself ignored. The
writer of nested mandatory-to-understand information is responsible
for ensuring that any enclosing element is also labelled with a
mustUnderstand='true' or mustUnderstand='1' attribute, if
necessary.
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This specification defines (section 4.1) elements within the
'urn:ietf:params:xml:ns:cpim-pidf' namespace that MUST be recognized
in CPIM presence data. Processors MUST handle these as described,
even if they do not carry a mustUnderstand attribute. The XML Schema
Definition (section 4.4) indicates those elements that MUST be
present in a valid presence information document.
If an agent receives PRESENCE INFORMATION containing an unrecognized
element with a mustUnderstand='true' (or '1') attribute, it should
treat the entire PRESENCE INFORMATION as unrecognized and not attempt
to process it.
4.2.4. Status Value Extensibility
This memo only defines the <basic> status value with values of "open"
and "closed". Other status values are possible using the standard
namespace-based extensibility rules defined above.
For example, a location status value might be included thus:
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
xmlns:local="urn:example-com:pidf-status-type"
entity="pres:someone@example.com">
<tuple id="im">
<status>
<basic>open</basic>
<local:location>home</local:location>
</status>
<contact>im:someone@example.com</contact>
</tuple>
</presence>
Some new status values will 'extend' the value of the <basic>
element. For example, a status value defined for use with instant
messaging may include values such as 'away', 'busy' and 'offline'. In
order that some level of interoperability be maintained with user
agents that don't recognise the new extension, the <basic> status
value must also be included. This means that extensions are not
obligated to define a mapping from each of their values to OPEN or
CLOSED.
4.3. Examples
4.3.1. Default Namespace with Status Extensions
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<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
xmlns:im="urn:ietf:params:xml:ns:cpim-pidf:im"
xmlns:myex="http://id.example.com/cpim-presence/"
entity="pres:someone@example.com">
<tuple id="mobile-im">
<status>
<basic>open</basic>
<im:im>busy</im:im>
<myex:location>home</myex:location>
</status>
<contact priority="0.8">im:someone@mobilecarrier.net</contact>
<note xml:lang="en">Don't Disturb Please!</note>
<note xml:lang="fr">Ne derangez pas, s'il vous plait</note>
<timestamp>2001-10-27T16:49:29Z</timestamp>
</tuple>
<tuple id="email">
<status>
<basic>open</basic>
</status>
<contact priority="1.0">mailto:someone@example.com</contact>
</tuple>
<note>I'll be in Tokyo next week</note>
</presence>
4.3.2. Presence with Other Extension Elements
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:cpim-pidf"
xmlns:myex="http://id.example.com/cpim-presence/"
entity="pres:someone@example.com">
<impp:tuple id="mobile-phone">
<impp:status>
<impp:basic>open</impp:basic>
</impp:status>
<myex:mytupleelement>Extended value in tuple</myex:mytupleelement>
<impp:contact priority="0.65">tel:09012345678</impp:contact>
</impp:tuple>
<impp:tuple id="mobile-im">
<impp:status>
<impp:basic>open</impp:basic>
</impp:status>
<impp:contact priority="1.0">
im:someone@mobilecarrier.net</impp:contact>
</impp:tuple>
<myex:mytag>My extended presentity information</myex:mytag>
</impp:presence>
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4.3.3. Example Mandatory To Understand Extensions
<?xml version="1.0" encoding="UTF-8"?>
<impp:presence xmlns:impp="urn:ietf:params:xml:ns:cpim-pidf"
xmlns:myex="http://id.mycompany.com/cpim-presence/"
entity="pres:someone@example.com">
<impp:tuple id="mobile-phone">
<impp:status>
<impp:basic>open</impp:basic>
</impp:status>
<myex:complexExtension impp:mustUnderstand="1">
<myex:ex1 impp:mustUnderstand="1">val1</myex:ex1>
<myex:ex2>val2</myex:ex2>
</myex:complexExtension>
<impp:contact priority="0.725">tel:09012345678</impp:contact>
</impp:tuple>
<myex:mytag>My extended presentity information</myex:mytag>
</impp:presence>
Here, <myex:complexExtension>, <myex:ex1> must be understood, but
<myex:mytag> and <myex:ex2> may be ignored if they are not
recognized.
4.4. XML Schema Definitions
This section gives the XML Schema Definition [XMLSchema1] of the
"application/cpim-pidf+xml" format. This is presented as a formal
definition of the "application/cpim-pidf+xml" format. Note that the
XML Schema definition is not intended to be used with on-the-fly
validation of the presence XML document.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:ietf:params:xml:ns:cpim-pidf"
xmlns:tns="urn:ietf:params:xml:ns:cpim-pidf"
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"
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maxOccurs="unbounded"/>
<xs:element name="note" type="tns:note" minOccurs="0"
maxOccurs="unbounded"/>
<xs:any namespace="##other" processContents="lax" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="entity" type="xs:anyURI" use="required"/>
</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">
<xs:attribute name="priority" type="tns:qvalue"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="note">
<xs:simpleContent>
<xs:extension base="xs:string">
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<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>
<!-- Global Attributes -->
<xs:attribute name="mustUnderstand" type="xs:boolean" default="0"/>
</xs:schema>
5. IANA Considerations
This memo calls for IANA to:
- register a new MIME content-type application/cpim-pidf+xml,
per [RFC 2048],
- register a new XML namespace URN per [XML-Registry].
The registration templates for these are below.
5.1. Content-type registration for 'application/cpim-pidf+xml'
To: ietf-types@iana.org
Subject: Registration of MIME media type application/cpim-pidf+xml
MIME media type name: application
MIME subtype name: cpim-pidf+xml
Required parameters: (none)
Optional parameters: charset
Indicates the character encoding of enclosed XML. Default is UTF-8.
Encoding considerations:
Uses XML, which can employ 8-bit characters, depending on the
character encoding used.
See RFC 3023 [RFC 3023], section 3.2.
Security considerations:
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This content type is designed to carry presence data, which may
be considered private information. Appropriate precautions should
be adopted to limit disclosure of this information.
Interoperability considerations:
This content type provides a common format for exchange of presence
information across different CPIM compliant protocols.
Published specification:
RFCXXXX (this document)
Applications which use this media type:
Presence and instant messaging systems.
Additional information:
Magic number(s):
File extension(s):
Macintosh File Type Code(s):
Person & email address to contact for further information:
Hiroyasu Sugano
E-mail: sugano.h@jp.fujitsu.com
Intended usage:
LIMITED USE
Author/Change controller:
This specification is a work item of the IETF IMPP working group,
with mailing list address <impp@iastate.edu>.
Other information:
This media type is a specialization of application/xml [RFC 3023],
and many of the considerations described there also apply to
application/cpim-pidf+xml.
5.2. URN sub-namespace registration for 'urn:ietf:params:xml:ns:cpim-
pidf'
URI
urn:ietf:params:xml:ns:cpim-pidf
Description:
This is the XML namespace URI for XML elements defined by [RFCXXXX]
to describe CPIM presence information in application/cpim-pidf+xml
content type.
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Registrant Contact
IETF, IMPP working group, <impp@iastate.edu>
Hiroyasu Sugano, <sugano.h@jp.fujitsu.com>
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"/>
<meta name="generator" content="Adobe GoLive 6"/>
<title>Welcome to Adobe GoLive 6</title>
</head>
<body>
<h1>Namespace for CPIM presence information</h1>
<h2>application/cpim-pidf+xml</h2>
<p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
6. Security Considerations
Because presence is very privacy-sensitive information, the transport
protocol for the presence information SHOULD have capabilities to
protect protocol messages from possible threats, such as
eavesdropping, corruption, tamper and replay attacks. The protocols
SHOULD be able to use security mechanisms which are standardized or
being standardized in IETF. However, it depends on the actual
transport protocols which security mechanisms should be used, and it
is beyond the scope of this memo.
7. Internationalization Considerations
This memo does not specify the use of specific character encodings by
itself. However, all the processors MUST be able to use the UTF-8
encoding because it is one of the mandatory character encodings for
XML conforming processors and also RFC 2277 requires the handling of
UTF-8 for the Internet protocols [RFC2277].
Other character encodings may be used if a particular protocol or
application using this specification needs them. In this case, a
conscious decision is needed about which character encoding(s) to
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allow in order to promote the interoperability.
8. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC2778] M. Day, J. Rosenberg, H. Sugano, "A Model for Presence and
Instant Messaging", RFC 2778, February 2000.
[RFC2779] M. Day, S. Aggarwal, G. Mohr, and J. Vincent, "Instant
Messaging / Presence Protocol Requirements", RFC 2779, February 2000.
[RFC3023] M. Murata, S. St.Laurent, D. Kohn, "XML Media Types",
RFC 3023, January 2001.
[XML] T. Bray, J. Paoli, C. Sperberg-McQueen and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)",
W3C Recommendation, October 2000,
<http://www.w3.org/TR/2000/REC-xml-20001006>
[MIME] Multipurpose Internet Mail Extensions. See RFC 822, RFC 2045,
RFC 2046, RFC 2047, RFC 2048, and RFC 2049.
[RFC1766] H. Alvestrand, "Tags for the Identification of Languages",
RFC 1766, March 1995.
[DateTime] G. Klyne and C.Newman, "Date and Time on the Internet:
Timestamps", draft-ietf-impp-datetime-05.txt, Work in Progress.
[XML-NS] Tim Bray, Dave Hollander, and Andrew Layman "Namespaces in
XML", W3C recommendation: xml-names, 14 January 1999,
<http://www.w3.org/TR/REC-xml-names>
[URI] T. Berners-Lee, R.T.Fielding and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
[URN] R. Moats, "URN Syntax", RFC 2141, May 1997.
[URN-NS-IETF] R. Moats, "A URN Namespace for IETF Documents", RFC
2648, August 1999.
[XML-Registry] M. Mealling, "The IETF XML Registry",
draft-mealling-iana-xmlns-registry-03, Work in Progress.
[RFC2277] H. Alvestrand, "IETF Policy on Character Sets and
Languages", RFC 2277, BCP 18, January 1998.
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[XMLSchema1] Thompson, H., Beech, D., Maloney, M. and N. Mendelsohn,
"XML Schema Part 1: Structures", W3C REC-xmlschema-1, May 2001,
<http://www.w3.org/TR/xmlschema-1/>.
[XMLSchema2] Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes",
W3C REC-xmlschema-2, May 2001, <http://www.w3.org/TR/xmlschema-2/>.
9. Informative References
[CPIM] D. Crocker et al., "Common Presence and Instant Messaging
(CPIM)", draft-ietf-impp-cpim-02.txt, Work in Progress.
[CPIM-MSG] D. Atkins and G. Klyne, "Common Presence and Instant
Messaging Message Format", draft-ietf-impp-cpim-msgfmt-06.txt,
Work in Progress.
[vCard] F. Dawson and T. Howes, "vCard MIME Directory Profile",
RFC 2426, September 1998.
10. Authors' Addresses
Hiroyasu Sugano
Fujitsu Laboratories Ltd.
64, Nishiwaki
Ohkubo-cho
Akashi 674-8555
Japan
E-mail: sugano.h@jp.fujitsu.com
Shingo Fujimoto
Fujitsu Laboratories Ltd.
64, Nishiwaki
Ohkubo-cho
Akashi 674-8555
Japan
E-mail: shingo_fujimoto@jp.fujitsu.com
Graham Klyne
Baltimore Technologies - Content Security Group,
1310 Waterside,
Arlington Business Park
Theale
Reading, RG7 4SA
United Kingdom.
Telephone: +44 118 903 8000
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Facsimile: +44 118 903 9000
E-mail: GK@ACM.ORG
Adrian Bateman
VisionTech Limited
Colton, Staffordshire, WS15 3LD
United Kingdom
E-mail: bateman@acm.org
Wayne Carr
Intel Corporation
2111 NE 25th Avenue
Hillsboro, OR 97124
USA
E-mail: wayne.carr@intel.com
11. Appendix A. Document Type Definitions
The Document Type Definition for the "application/cpim-pidf+xml"
format is described. The DTD here is presented only for
informational for those who may not familiar with the XML Schema
definition.
Note: the DTD does not show where extension elements can be added.
See the XML Schema for that information.
<!ENTITY % URL "CDATA">
<!ENTITY % URI "CDATA">
<!ENTITY % TUPLEID "CDATA">
<!ENTITY % DATETIME "CDATA">
<!ENTITY % VALUETYPE "CDATA">
<!ENTITY % PRIORITY "CDATA">
<!ENTITY % NOTE "CDATA">
<!ELEMENT presence ((tuple+),note?)>
<!ATTLIST presence
xmlns %URI; #REQUIRED
entity %URL; #REQUIRED
>
<!ELEMENT tuple (status,contact?,note?,timestamp?)>
<!ATTLIST tuple
id %TUPLEID; #REQUIRED
>
<!ELEMENT status (basic?)>
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<!ELEMENT basic CDATA>
<!ELEMENT contact %URL;>
<!ATTLIST contact
priority %PRIORITY; #IMPLIED
>
<!ELEMENT note %NOTE;>
<!ELEMENT timestamp %DATETIME;>
12. Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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