A SIP Event Package for Subscribing to Changes to an HTTP Resource
RFC 5989

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Internet Engineering Task Force (IETF)                        A.B. Roach
Request for Comments: 5989                                       Tekelec
Category: Standards Track                                   October 2010
ISSN: 2070-1721

   A SIP Event Package for Subscribing to Changes to an HTTP Resource

Abstract

   The Session Initiation Protocol (SIP) is increasingly being used in
   systems that are tightly coupled with Hypertext Transport Protocol
   (HTTP) servers for a variety of reasons.  In many of these cases,
   applications can benefit from being able to discover, in near real-
   time, when a specific HTTP resource is created, changed, or deleted.
   This document proposes a mechanism, based on the SIP Event Framework,
   for doing so.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5989.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Roach                        Standards Track                    [Page 1]
RFC 5989                 SIP HTTP Subscriptions             October 2010

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Associating Monitoring SIP URIs with HTTP URLs ..................3
      3.1. Monitoring a Single HTTP Resource ..........................4
      3.2. Monitoring Multiple HTTP Resources .........................5
   4. HTTP Change Event Package .......................................6
      4.1. Event Package Name .........................................6
      4.2. Event Package Parameters ...................................6
      4.3. SUBSCRIBE Bodies ...........................................7
      4.4. Subscription Duration ......................................7
      4.5. NOTIFY Bodies ..............................................8
           4.5.1. Use of message/http in HTTP Monitor Event Package ...8
      4.6. Notifier Processing of SUBSCRIBE Requests ..................9
      4.7. Notifier Generation of NOTIFY Requests .....................9
      4.8. Subscriber Processing of NOTIFY Requests ...................9
      4.9. Handling of Forked Requests ...............................10
      4.10. Rate of Notifications ....................................10
      4.11. State Agents .............................................10
   5. Example Message Flow ...........................................10
   6. Security Considerations ........................................14
   7. IANA Considerations ............................................15
      7.1. New Link Relations ........................................15
           7.1.1. New Link Relation: monitor .........................15
           7.1.2. New Link Relation: monitor-group ...................16
      7.2. New SIP Event Package: http-monitor .......................16
      7.3. New Event Header Field Parameter: body ....................16
   8. Acknowledgements ...............................................16
   9. References .....................................................17
      9.1. Normative References ......................................17
      9.2. Informative References ....................................18
   Appendix A.  Rationale: Other Approaches Considered ...............19

Roach                        Standards Track                    [Page 2]
RFC 5989                 SIP HTTP Subscriptions             October 2010

1.  Introduction

   The Session Initiation Protocol (SIP) [3] is increasingly being used
   in systems that are tightly coupled with Hypertext Transport Protocol
   (HTTP) [2] servers for a variety of reasons.  In many of these cases,
   applications can benefit from learning of changes to specified HTTP
   resources in near real-time.  For example, user agent terminals may