Internet Engineering Task Force SIMPLE WG Internet Draft J. Rosenberg dynamicsoft D. Willis dynamicsoft R. Sparks dynamicsoft B. Campbell dynamicsoft H. Schulzrinne Columbia U. J. Lennox Columbia U. C. Huitema Microsoft B. Aboba Microsoft D. Gurle Microsoft draft-ietf-simple-winfo-format-01.txt March 1, 2002 Expires: September 2002 An XML Based Format for Watcher Information 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 Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt To view the list Internet-Draft Shadow Directories, see http://www.ietf.org/shadow.html. J. Rosenberg et. al. [Page 1] Internet Draft Watcher Info March 1, 2002 Abstract Watchers are defined as entities that request (i.e., subscribe to) information about a resource. There is fairly complex state associated with these subscriptions. The union of the state for all subscriptions to a particular resource is called the watcher information for that resource. This state is dynamic, changing as subscribers come and go. As a result, it is possible, and indeed useful, to subscribe to the watcher information for a particular resource. In order to enable this, a format is needed to describe the state of watchers on a resource. This specification describes an XML document format for such state. J. Rosenberg et. al. [Page 2] Internet Draft Watcher Info March 1, 2002 Table of Contents 1 Introduction ........................................ 4 2 Structure of Watcher Information .................... 4 3 Document Identifiers ................................ 6 4 Example ............................................. 6 5 XML DTD ............................................. 7 6 Security Considerations ............................. 8 7 IANA Considerations ................................. 8 8 Authors Addresses ................................... 8 9 Normative References ................................ 9 10 Informative References .............................. 9 J. Rosenberg et. al. [Page 3] Internet Draft Watcher Info March 1, 2002 1 Introduction Watchers are defined as entities that request (i.e., subscribe to) information about a resource, using the SIP Events framework [1]. There is fairly complex state associated with these subscriptions. This state includes the identity of the subscriber, the state of the subscription, and so on. The union of the state for all subscriptions to a particular resource is called the watcher information for that resource. This state is dynamic, changing as subscribers come and go. As a result, it is possible, and indeed useful, to subscribe to the watcher information for a particular resource. An important application of this is the ability of a user to find out the set of subscribers to their presentity [4]. This would allow the user to provide an authorization decision for the subscription. To support subscriptions to watcher information, two components are needed. The first is the definition of a SIP Events package for watcher information. The other is the definition of a data format to represent watcher information. The former is specified in [2], and the latter is specified here. 2 Structure of Watcher Information Watcher information is an XML document that begins with the root element tag "watcherinfo". It consists of any number of "resource" sub-elements, describing all the resources being watched. Each resource element has an attribute giving the URI for the resource, and an attribute for indicating the event package for which watcher information on that resource is being provided. The resource element contains sub-elements representing a list of the watchers for this resource. package CDATA #REQUIRED> The watcher element describes a user watching the enclosing resource. J. Rosenberg et. al. [Page 4] Internet Draft Watcher Info March 1, 2002 Mr. Subscriber 5 XML DTD package CDATA #REQUIRED>