A Presence Event Package for the Session Initiation Protocol (SIP)
RFC 3856

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Network Working Group                                       J. Rosenberg
Request for Comments: 3856                                   dynamicsoft
Category: Standards Track                                    August 2004

   A Presence Event Package for the Session Initiation Protocol (SIP)

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 (2004).

Abstract

   This document describes the usage of the Session Initiation Protocol
   (SIP) for subscriptions and notifications of presence.  Presence is
   defined as the willingness and ability of a user to communicate with
   other users on the network.  Historically, presence has been limited
   to "on-line" and "off-line" indicators; the notion of presence here
   is broader.  Subscriptions and notifications of presence are
   supported by defining an event package within the general SIP event
   notification framework.  This protocol is also compliant with the
   Common Presence Profile (CPP) framework.

Table of Contents

   1.  Introduction ................................................   2
   2.  Terminology .................................................   3
   3.  Definitions .................................................   3
   4.  Overview of Operation .......................................   4
   5.  Usage of Presence URIs ......................................   6
   6.  Presence Event Package ......................................   7
       6.1.  Package Name ..........................................   8
       6.2.  Event Package Parameters ..............................   8
       6.3.  SUBSCRIBE Bodies ......................................   8
       6.4.  Subscription Duration .................................   9
       6.5.  NOTIFY Bodies .........................................   9
       6.6.  Notifier Processing of SUBSCRIBE Requests .............   9
             6.6.1. Authentication .................................  10
             6.6.2. Authorization ..................................  10
       6.7.  Notifier Generation of NOTIFY Requests ................  11

Rosenberg                   Standards Track                     [Page 1]
RFC 3856                      SIP Presence                   August 2004

       6.8.  Subscriber Processing of NOTIFY Requests ..............  13
       6.9.  Handling of Forked Requests ...........................  13
       6.10. Rate of Notifications .................................  14
       6.11. State Agents ..........................................  14
             6.11.1. Aggregation, Authentication, and Authorization.  14
             6.11.2. Migration .....................................  15
   7.  Learning Presence State .....................................  16
       7.1.  Co-location ...........................................  16
       7.2.  REGISTER ..............................................  16
       7.3.  Uploading Presence Documents ..........................  17
   8.  Example Message Flow ........................................  17
   9.  Security Considerations .....................................  20
       9.1.  Confidentiality .......................................  20
       9.2.  Message Integrity and Authenticity ....................  21
       9.3.  Outbound Authentication ...............................  22
       9.4.  Replay Prevention .....................................  22
       9.5.  Denial of Service Attacks Against Third Parties .......  22
       9.6.  Denial Of Service Attacks Against Servers .............  23
   10. IANA Considerations .........................................  23
   11. Contributors ................................................  24
   12. Acknowledgements ............................................  25
   13. Normative References ........................................  25
   14. Informative References ......................................  26
   15. Author's Address ............................................  26
   16. Full Copyright Statement ....................................  27

1.  Introduction

   Presence, also known as presence information, 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.  In that model, a presence service is a
   system that accepts, stores, and distributes presence information to
   interested parties, called watchers.  A presence protocol is a
   protocol for providing a presence service over the Internet or any IP
   network.

   This document proposes the usage of the Session Initiation Protocol