An Extensible Markup Language (XML)-Based Format for Event Notification Filtering
RFC 4661

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Network Working Group                                       H. Khartabil
Request for Comments: 4661                                         Telio
Category: Standards Track                                    E. Leppanen
                                                             M. Lonnfors
                                                        J. Costa-Requena
                                                                   Nokia
                                                          September 2006

          An Extensible Markup Language (XML)-Based Format for
                      Event Notification Filtering

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

   The SIP event notification framework describes the usage of the
   Session Initiation Protocol (SIP) for subscriptions and notifications
   of changes to a state of a resource.  The document does not describe
   a mechanism whereby filtering of event notification information can
   be achieved.  Filtering is a mechanism for defining the preferred
   notification information to be delivered and for specifying triggers
   that cause that information to be delivered.  In order to enable
   this, a format is needed to enable the subscriber to describe the
   state changes of a resource that cause notifications to be sent to it
   and what those notifications are to contain.  This document presents
   a format in the form of an XML document.

Khartabil, et al.           Standards Track                     [Page 1]
RFC 4661             XML Based Format for Filtering       September 2006

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Structure of XML-Encoded Simple-Filter . . . . . . . . . . . .  4
       3.1.  MIME Type for Simple-Filter Document . . . . . . . . . .  4
       3.2.  The <filter-set> Root Element  . . . . . . . . . . . . .  4
       3.3.  The <ns-bindings> Element  . . . . . . . . . . . . . . .  4
       3.4.  The <filter> Element . . . . . . . . . . . . . . . . . .  5
       3.5.  The <what> Element . . . . . . . . . . . . . . . . . . .  6
             3.5.1.  The <include> Element  . . . . . . . . . . . . .  6
             3.5.2.  The <exclude> Element  . . . . . . . . . . . . .  7
             3.5.3.  The 'type' Attribute . . . . . . . . . . . . . .  7
       3.6.  The <trigger> Element  . . . . . . . . . . . . . . . . .  8
             3.6.1.  The <changed> Element  . . . . . . . . . . . . .  8
             3.6.2.  The <added> Element  . . . . . . . . . . . . . .  9
             3.6.3.  The <removed> Element  . . . . . . . . . . . . . 10
   4.  XML Schema Extensibility . . . . . . . . . . . . . . . . . . . 10
   5.  Syntax for Referencing XML Items and Making Logical
       Expressions  . . . . . . . . . . . . . . . . . . . . . . . . . 10
   6.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
       6.1.  Filter Criteria Using <what> Element . . . . . . . . . . 12
       6.2.  Filter Criteria Using <trigger> Element  . . . . . . . . 13
       6.3.  Filter Criteria Using <what> and <trigger> Elements  . . 13
       6.4.  Content Filter Using Namespaces  . . . . . . . . . . . . 14
       6.5.  Content Filter Using Only <include> Elements . . . . . . 14
       6.6.  Two Content Filters as Filter Criteria . . . . . . . . . 15
   7.  XML Schema for Filter Criteria . . . . . . . . . . . . . . . . 16
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
       9.1.  application/simple-filter+xml MIME TYPE  . . . . . . . . 19
       9.2.  URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:simple-filter . . . . . . . . . . . 20
       9.3.  Schema Registration  . . . . . . . . . . . . . . . . . . 20
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
       11.1. Normative References . . . . . . . . . . . . . . . . . . 20
       11.2. Informative References . . . . . . . . . . . . . . . . . 21

Khartabil, et al.           Standards Track                     [Page 2]
RFC 4661             XML Based Format for Filtering       September 2006

1.  Introduction

   The SIP event notification framework [2] describes the usage of the
   Session Initiation Protocol (SIP) for subscriptions and notifications
   of changes to a state of a resource.  The document does not describe