SIMPLE J. Rosenberg Internet-Draft dynamicsoft Expires: November 24, 2003 May 26, 2003 An Extensible Markup Language (XML) Configuration Access Protocol (XCAP) Usage for Presence Lists draft-rosenberg-simple-xcap-list-usage-00 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. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on November 24, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document describes a usage of the Extensible Markup Language (XML) Configuration Access Protocol (XCAP) for manipulating lists of presentities (also known as buddy lists or rosters). It does so by specifying an XML Schema that contains a list of presentities that a user is interested in watching. Rosenberg Expires November 24, 2003 [Page 1] Internet-Draft XCAP Usage for Presence Lists May 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Application Unique ID . . . . . . . . . . . . . . . . . . . 5 4. Structure of a Presence List . . . . . . . . . . . . . . . . 6 5. Computed Data . . . . . . . . . . . . . . . . . . . . . . . 8 6. Additional Constraints . . . . . . . . . . . . . . . . . . . 9 7. Naming Conventions . . . . . . . . . . . . . . . . . . . . . 10 8. Authorization Policies . . . . . . . . . . . . . . . . . . . 11 9. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. Example Document . . . . . . . . . . . . . . . . . . . . . . 13 11. Security Considerations . . . . . . . . . . . . . . . . . . 14 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 15 12.1 XCAP Application Usage ID . . . . . . . . . . . . . . . . . 15 12.2 application/presence-lists+xml MIME Type . . . . . . . . . . 15 12.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:presence-lists . . . . . . . . . . . 16 Normative References . . . . . . . . . . . . . . . . . . . . 17 Informative References . . . . . . . . . . . . . . . . . . . 18 Author's Address . . . . . . . . . . . . . . . . . . . . . . 18 Intellectual Property and Copyright Statements . . . . . . . 19 Rosenberg Expires November 24, 2003 [Page 2] Internet-Draft XCAP Usage for Presence Lists May 2003 1. Introduction The Session Initiation Protocol (SIP) for Instant Messaging and Presence (SIMPLE) specifications allow a user, called a watcher, to subscribe to another user, called a presentity [7], in order to learn their presence information [8]. In many cases, a watcher will be interested in not just a single presentity, but a list of presentities. Such a list of presentities is called a presence list. When a user wants to subscribe to their presence list, the procedures in [8] require the watcher to create and manage a subscription for each presentity in their list. For large lists, the bandwidth required to do this can be a problem, particularly for wireless networks. An extension to the SIP events framework [9] has been defined. The extension allows a watcher to subscribe to a list of resources, using a single subscription [10]. This mechanism assumes that a server, called the Resource List Server (RLS) has a copy of the presence list that the user wishes to subscribe to. By using protocols such as the XML Configuration Access Protocol (XCAP) [12], a client can place this list on the server, and manipulate it as needed. XCAP requires application usages to standardize several pieces of information, including an application unique ID (AUID), an XML schema, and various other pieces of information. This specification fulfills those requirements. The XML schema defined here has several other usages outside of XCAP: 1. A PC client application will need to know the users in the presence list, so that it can generate a subscription to each one. This information represents user provisioned data for the application. Typically, this information is stored on local disk in a proprietary file format. By defining a standard format, the same list can be used by a multiplicity of different client applications, providing portability across them. 2. It is common for users to share presence lists. As an example, user A may have three people in their list that they wish to tell user B about. User A would like to send an email to user B with an attachment describing these three people. Should user B open the attachment, the three people can be added to their own presence list. Doing this requires a standardized format for exchanging lists over email, instant messaging, and other communications protocols. Rosenberg Expires November 24, 2003 [Page 3] Internet-Draft XCAP Usage for Presence Lists May 2003 2. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and indicate requirement levels for compliant implementations. Rosenberg Expires November 24, 2003 [Page 4] Internet-Draft XCAP Usage for Presence Lists May 2003 3. Application Unique ID XCAP requires application usages to define a unique application usage ID (AUID) in either the IETF tree or a vendor tree. This specification defines the "presence-lists" AUID within the IETF tree, via the IANA registration in Section 12. Rosenberg Expires November 24, 2003 [Page 5] Internet-Draft XCAP Usage for Presence Lists May 2003 4. Structure of a Presence List A presence list is an XML [2] document that MUST be well-formed and SHOULD be valid. Presence list documents MUST be based on XML 1.0 and MUST be encoded using UTF-8. This specification makes use of XML namespaces for identifying presence list documents and document fragments. The namespace URI for elements defined by this specification is a URN [3], using the namespace identifier 'ietf' defined by [5] and extended by [6]. This URN is: urn:ietf:params:xml:ns:presence-lists A presence list document begins with the root element tag ``presence-lists''. It consists of any number of ``list'' sub-elements, each of which is a presence list. Other elements from different namespaces MAY be present for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. There are three attributes associated with this element. The first two, "name", and "subscribable" MUST be present: name: This attribute is a descriptive name for the list. It MUST be unique amongst all other list elements within the same parent element. subscribable: This boolean attribute indicates whether or not the list is subscribable or not. The other attribute, "uri" MAY be present: uri: This attribute provides a URI that can be used to subscribe to the list, using the SIP event notification extension for lists [10]. As a result, the URI MUST be either a SIP URI or a pres URI [11]. [[OPEN ISSUE: Do we want this to be a comma separated list, so that a presence list can have any number of valid aliases?]] [[OPEN ISSUE: We also need to define policy about who is allowed to subscribe to the list. We can either integrate that into the list definition described here, or handle that as a separate policy specification. The SEACAP proposal kept them together. I believe now that they should be kept separate.]] Each list element is composed of a sequence of entry elements or list elements. The ability of a list element to contain other list elements means that a presence list can be hierarchically structured. An entry element describes a single presentity that is part of the list. A list element can also contain elements from other namespaces, for the purposes of extensibility. Rosenberg Expires November 24, 2003 [Page 6] Internet-Draft XCAP Usage for Presence Lists May 2003 The entry element describes a single presentity. The entry element has two attributes: name: This mandatory attribute is a unique identifier amongst all other entry elements of the same parent. uri: This optional attribute is a URI that is used to subscribe to the presentity. It MUST be either a SIP or pres URI. The entry element contains a sequence of other elements. Only one such element is defined at this time, which is the display-name. This element provides a UTF-8 encoded string, meant for consumption by the user, that describes the presentity. Unlike the "name" attribute of the entry element, the display-name has no uniqueness requirements. [[OPEN ISSUE: Do we need this in addition to the name attribute?]]. Other elements from other namespaces MAY be included. This is meant to support the inclusion of other information about the entry, such as a phone number or postal address. Rosenberg Expires November 24, 2003 [Page 7] Internet-Draft XCAP Usage for Presence Lists May 2003 5. Computed Data An XCAP server supporting this application usage need only worry about a single piece of computed data - the "uri" attribute of the list element. If the "uri" attribute is absent in a document written to an XCAP server, but the "subscribable" flag is true, the XCAP server MUST allocate a URI for this list. This allocated URI MUST be globally unique, and MUST route to an RLS which will handle list subscriptions for the list defined by the document. The server MUST set the uri attribute of the document with this URI. A server MUST NOT delete the "uri" attribute, however, should a client change the subscribable flag to false after the server has allocated a URI. Rosenberg Expires November 24, 2003 [Page 8] Internet-Draft XCAP Usage for Presence Lists May 2003 6. Additional Constraints There are no constraints on the document beyond those described in the schema. Rosenberg Expires November 24, 2003 [Page 9] Internet-Draft XCAP Usage for Presence Lists May 2003 7. Naming Conventions There are no naming conventions that need to be defined for this application usage. A subscription to a presence list will be to a specific URI. That URI will be one of the "uri" attributes defined in a list within one of the documents managed by an XCAP server. Rosenberg Expires November 24, 2003 [Page 10] Internet-Draft XCAP Usage for Presence Lists May 2003 8. Authorization Policies This application usage does not modify the default XCAP authorization policy, which is that only a user can read, write or modify their own documents. A server can allow priveleged users to modify documents that they don't own, but the establishment and indication of such policies is outside the scope of this document. Rosenberg Expires November 24, 2003 [Page 11] Internet-Draft XCAP Usage for Presence Lists May 2003 9. XML Schema The following is the XML schema definition of the presence list: Rosenberg Expires November 24, 2003 [Page 12] Internet-Draft XCAP Usage for Presence Lists May 2003 10. Example Document The following is an example of a document compliant to the schema: Bill Doe Joe Smith Nancy Gross Rosenberg Expires November 24, 2003 [Page 13] Internet-Draft XCAP Usage for Presence Lists May 2003 11. Security Considerations The configuration information defined by this application usage is particularly sensitive. It represents the principle set of people with whom a user would like to communicate. As a result, clients SHOULD use TLS when contacting servers in order to fetch this information. Note that this does not represent a change in requirement strength from XCAP. Rosenberg Expires November 24, 2003 [Page 14] Internet-Draft XCAP Usage for Presence Lists May 2003 12. IANA Considerations There are several IANA considerations associated with this specification. 12.1 XCAP Application Usage ID This section registers a new XCAP Application Usage ID (AUID) according to the IANA procedures defined in [12]. Name of the AUID: presence-lists Description: A presence list application is a usage of the SIP events framework (RFC 3265) [9] along with its list extension [10], for subscribing to a list of presentities (RFC2778) [7] stored at a server. 12.2 application/presence-lists+xml MIME Type MIME media type name: application MIME subtype name: presence-lists+xml Mandatory parameters: none Optional parameters: Same as charset parameter application/xml as specified in RFC 3023 [4]. Encoding considerations: Same as encoding considerations of application/xml as specified in RFC 3023 [4]. Security considerations: See Section 10 of RFC 3023 [4] and Section 11 of this specification. Interoperability considerations: none. Published specification: This document. Applications which use this media type: This document type has been used to support subscriptions to lists of users [10] for SIP-based presence [8]. Additional Information: Magic Number: None Rosenberg Expires November 24, 2003 [Page 15] Internet-Draft XCAP Usage for Presence Lists May 2003 File Extension: .pl or .xml Macintosh file type code: "TEXT" Personal and email address for further information: Jonathan Rosenberg, jdrosen@jdrosen.net Intended usage: COMMON Author/Change controller: The IETF. 12.3 URN Sub-Namespace Registration for urn:ietf:params:xml:ns:presence-lists This section registers a new XML namespace, as per the guidelines in [6] URI: The URI for this namespace is urn:ietf:params:xml:ns:presence-lists. Registrant Contact: IETF, SIMPLE working group, (simple@mailman.dynamicsoft.com), Jonathan Rosenberg (jdrosen@jdrosen.net). XML: BEGIN Presence Lists Namespace

Namespace for Presence Lists

application/presence-lists+xml

See RFCXXXX.

END Rosenberg Expires November 24, 2003 [Page 16] Internet-Draft XCAP Usage for Presence Lists May 2003 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C REC REC-xml-20001006, October 2000. [3] Moats, R., "URN Syntax", RFC 2141, May 1997. [4] Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC 3023, January 2001. [5] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999. [6] Mealling, M., "The IETF XML Registry", draft-mealling-iana-xmlns-registry-04 (work in progress), July 2002. Rosenberg Expires November 24, 2003 [Page 17] Internet-Draft XCAP Usage for Presence Lists May 2003 Informative References [7] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [8] Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work in progress), January 2003. [9] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [10] Rosenberg, J., Roach, A. and B. Campbell, "A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists", draft-ietf-simple-event-list-03 (work in progress), May 2003. [11] Peterson, J., "Common Profile for Presence (CPP)", draft-ietf-impp-pres-03 (work in progress), May 2003. [12] Rosenberg, J., "The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)", draft-rosenberg-simple-xcap-00 (work in progress), May 2003. Author's Address Jonathan Rosenberg dynamicsoft 600 Lanidex Plaza Parsippany, NJ 07052 US Phone: +1 973 952-5000 EMail: jdrosen@dynamicsoft.com URI: http://www.jdrosen.net Rosenberg Expires November 24, 2003 [Page 18] Internet-Draft XCAP Usage for Presence Lists May 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION Rosenberg Expires November 24, 2003 [Page 19] Internet-Draft XCAP Usage for Presence Lists May 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Rosenberg Expires November 24, 2003 [Page 20]