A Data Model for Presence
RFC 4479
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RFC - Proposed Standard
(July 2006; Errata)
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Last updated |
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2015-10-14
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IETF
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plain text
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(None)
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No shepherd assigned
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IESG state |
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RFC 4479 (Proposed Standard)
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Unknown
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Telechat date |
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Responsible AD |
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Ted Hardie
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Network Working Group J. Rosenberg
Request for Comments: 4479 Cisco Systems
Category: Standards Track July 2006
A Data Model for Presence
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines the underlying presence data model used by
Session Initiation Protocol (SIP) for Instant Messaging and Presence
Leveraging Extensions (SIMPLE) presence agents. The data model
provides guidance on how to map various communications systems into
presence documents in a consistent fashion.
Rosenberg Standards Track [Page 1]
RFC 4479 Presence Data Model July 2006
Table of Contents
1. Introduction ....................................................2
2. Definitions .....................................................3
3. The Model .......................................................5
3.1. Presentity URI .............................................6
3.2. Person .....................................................7
3.3. Service ....................................................8
3.3.1. Characteristics .....................................9
3.3.2. Reach Information ..................................10
3.3.3. Relative Information ...............................13
3.3.4. Status .............................................13
3.4. Device ....................................................15
3.5. Modeling Ambiguity ........................................17
3.6. The Meaning of Nothing ....................................19
3.7. Status vs. Characteristics ................................19
3.8. Presence Document Properties ..............................20
4. Motivation for the Model .......................................21
5. Encoding .......................................................22
5.1. XML Schemas ...............................................24
5.1.1. Common Schema ......................................24
5.1.2. Data Model .........................................25
6. Extending the Presence Model ...................................26
7. Example Presence Document ......................................26
7.1. Basic IM Client ...........................................27
8. Security Considerations ........................................29
9. Internationalization Considerations ............................29
10. IANA Considerations ...........................................30
10.1. URN Sub-Namespace Registration ...........................30
10.2. XML Schema Registrations .................................31
10.2.1. Common Schema .....................................31
10.2.2. Data Model ........................................31
11. Acknowledgements ..............................................31
12. References ....................................................32
12.1. Normative References .....................................32
12.2. Informative References ...................................32
1. Introduction
Presence conveys the ability and willingness of a user to communicate
across a set of devices. RFC 2778 [10] defines a model and
terminology for describing systems that provide presence information.
RFC 3863 [1] defines an XML [5] [6] [7] document format for
representing presence information. In these specifications, presence
information is modeled as a series of tuples, each of which contains
a status, communications address, and other markup. However, neither
specification gives guidance on exactly what a tuple is meant to
model, or how to map real-world communications systems (and in
Rosenberg Standards Track [Page 2]
RFC 4479 Presence Data Model July 2006
particular, those built around the Session Initiation Protocol (SIP)
[11]) into a presence document.
In particular, several important concepts are not clearly modeled or
well delineated by RFCs 2778 and 3863. These are the following:
Service: A communications service, such as instant messaging (IM) or
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