SIMPLE WG O. Levin Internet-Draft Microsoft Corporation Expires: May 1, 2004 Nov 2003 Ad-hoc Resource Lists using SUBSCRIBE in SIMPLE draft-levin-simple-adhoc-list-01.txt 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 May 1, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document presents an extension to the Session Initiation Protocol (SIP)-Specific Event Notification mechanism for subscribing to a homogeneous list of resources. Instead of the subscriber sending a SUBSCRIBE for each resource individually, the subscriber can define an ad-hoc resource list, subscribe to it, and maintain it – all within a single SUBSCRIBE dialog. Changes in the state of the resources are reported using NOTIFY within the same dialog in any standard SIMPLE format for conveying notifications for lists of resources or for individual resources and specified as "accepted" during the SUBSCRIBE dialog establishment. Levin Expires May 1, 2004 [Page 1] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 Table of Contents 1. Conventions and Terminology . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Overview of Operation . . . . . . . . . . . . . . . . . . . . 3 4. Example Message Flow . . . . . . . . . . . . . . . . . . . . . 4 5. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1 Formal Definition . . . . . . . . . . . . . . . . . . . . . . 8 5.2 XML Document Examples . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7.1 New SIP Option Tag: adhoclist . . . . . . . . . . . . . . . . 9 7.2 New MIME type for Resource List Meta-Information . . . . . . . 9 7.3 URN Sub-Namespace . . . . . . . . . . . . . . . . . . . . . . 11 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 Normative References . . . . . . . . . . . . . . . . . . . . . 11 Informational References . . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . 13 Levin Expires May 1, 2004 [Page 2] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 1. Conventions and Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. This document uses the Resource List Server (RLS) definition from [8]. 2. Introduction This document presents an extension to the Session Initiation Protocol (SIP)-Specific Event Notification mechanism for subscribing to a homogeneous list of resources. Instead of the subscriber sending a SUBSCRIBE for each resource individually, the subscriber can define an ad-hoc resource list, subscribe to it, and maintain it – all within a single SUBSCRIBE dialog. Changes in the state of the resources are reported using the same dialog in any standard SIMPLE format for conveying notifications for lists of resources (such as [8] and [9]) or individual resources (such as [6]) and agreed during the SUBSCRIBE dialog establishment. This document defines a new XML schema for creation and maintenance of a homogeneous list of resources and a new SIP option tag for expressing support for this schema. 3. Overview of Operation Before using the ad-hoc list subscription, a subscriber needs to know that the RLS supports this mode of operation. In order to do so, the subscriber SHOULD issue OPTIONS request and ensure that the SIP "adhoclist" option tag is included in the RLS response. Once the subscriber knows that the RLS supports ad-hoc list operations, a Require header MUST be set to "adhoclist" and an initial resources list can be included in the SUBSCRIBE. It is the responsibility of the subscriber to create the list name. The "adhoclist" attributes "uri" and "name" together MUST uniquely identify the list within the SUBSCRIBE dialog. The value in the Request URI in SUBSCRIBE MAY match the value of "uri" attribute of the "adhoclist". The RLS MUST store and maintain the ad-hoc list for the life of the SUBSCRIBE dialog. Notification format is negotiated by including appropriate SIP option tags in the Accept headers of SUBSCRIBE and corresponding Responses and is out of scope of this document. Levin Expires May 1, 2004 [Page 3] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 The subscriber can update the list by using the defined "create", "add", and "delete" primitives. "create" primitive means that the old list MUST be removed and replaced with the new data. Consequently, "create" primitive with an empty list means that the old list MUST be emptied. Adding an already existing resource MUST result in triggering of appropriate notifications. Deleting of a non-existent resource SHOULD NOT result in an error condition. If a subset of the resources specified in (re-)SUBSCRIBE cannot be served within the context of this dialog, error or redirection indications (preferably specified per resource) SHOULD be reported using subsequent NOTIFY(s) in accordance with the notification format(s) established for this SUBSCRIBE dialog. When any in-band operation is performed on a resource in the list, the RLS SHOULD generate a NOTIFY as if the operation has been performed by any possible out-of-band means and in accordance with the notification mechanism and the format established for this dialog. 4. Example Message Flow This message flow illustrates how a User (i.e. watcher) subscribes to its Presence Server for a list of resources, receives presence information about the resources, manipulates the list and receives updated information about the resources. When the value of the Content-Length header field is "..." this means that the value is whatever the computed length of the body is. For brevity some of the headers (e.g. Via, CSeq, and Max-Forwards) are omitted from the message flows. User Local RLS Resource | F1 SUBSCRIBE | | |----------------------->| | | F2 200 OK | | |<-----------------------| | | F3 NOTIFY | | |<-----------------------| | | F4 200 OK | | |----------------------->| | | | | | |F5 Update presence | | |<------------------ | Levin Expires May 1, 2004 [Page 4] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 | | | | F6 NOTIFY | | |<-----------------------| | | F7 200 OK | | |----------------------->| | | F8 SUBSCRIBE | | |----------------------->| | | F9 200 OK | | |<-----------------------| | | F10 NOTIFY | | |<-----------------------| | | F11 200 OK | | |----------------------->| | F1 SUBSCRIBE user (watcher) -> server (local RLS) SUBSCRIBE sip:user@pres.example.com SIP/2.0 To: From: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Require: adhoclist Accept: application/cpim-pidf+xml Accept: application/rlmi+xml Contact: Content-Type: application/adrl+xml Content-Length: ... [ADRL Document] F2 200 OK server -> user SIP/2.0 200 OK To: ;tag=33333 From: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Accept: application/adrl+xml Contact: sip:pres.example.com Content-Length: 0 F3 NOTIFY server -> user NOTIFY sip:user@terminal.example.com SIP/2.0 Levin Expires May 1, 2004 [Page 5] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Subscription-State: active;expires=750 Contact: sip:pres.example.com Content-Type: application/rlmi+xml Content-Length: ... [RLMI Document] F4 200 OK user -> server SIP/2.0 200 OK From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Content-Length: 0 F5 Resources’ information on the RLS is being updated by SIP or non-SIP means. Details are out of scope of this specification. F6 NOTIFY server -> user NOTIFY sip:user@terminal.example.com SIP/2.0 From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Subscription-State: active;expires=750 Contact: sip:pres.example.com Content-Type: application/rlmi+xml Content-Length: ... [RLMI Document] F7 200 OK user -> server SIP/2.0 200 OK From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Content-Length: 0 F8 SUBSCRIBE user (watcher) -> server (local RLS) SUBSCRIBE sip:user@pres.example.com SIP/2.0 To: Levin Expires May 1, 2004 [Page 6] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 From: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Require: adhoclist Accept: application/cpim-pidf+xml Accept: application/rlmi+xml Contact: Content-Type: application/adrl+xml Content-Length: ... [ADRL Document] F9 200 OK server -> user SIP/2.0 200 OK To: ;tag=33333 From: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Accept: application/adrl+xml Contact: sip:pres.example.com Content-Length: 0 F10 NOTIFY server -> user NOTIFY sip:user@terminal.example.com SIP/2.0 From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Event: presence Subscription-State: active;expires=650 Contact: sip:pres.example.com Content-Type: application/rlmi+xml Content-Length: ... [RLMI Document] F11 200 OK user -> server SIP/2.0 200 OK From: ;tag=33333 To: ;tag=22222 Call-ID: 2345@terminal.example.com Content-Length: 0 Levin Expires May 1, 2004 [Page 7] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 5. XML Schema 5.1 Formal Definition The schema for the adrl+xml XML document is given below. 5.2 XML Document Examples The example shows an update on Ann's ad-hoc list of friends: three Levin Expires May 1, 2004 [Page 8] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 friends are added to the list and one is deleted. 6. Security Considerations The functionality described in this document doesn't introduce new security risks beyond described in [7] for subscription to a single resource. Note that security considerations related to conveying resources' information using NOTIFYs are addressed by corresponding drafts (e.g. [8], [9], and [6]). 7. IANA Considerations 7.1 New SIP Option Tag: adhoclist This section defines a new option tag for the registry established by section 27.1 of RFC 3261[1]. Option Tag Name: adhoclist Description: Extension to allow creation of and subscription to lists of resources Published specification: RFC xxxx [[Note to RFC editor: replace xxxx with the RFC number of this document when published]] 7.2 New MIME type for Resource List Meta-Information MIME Media Type Name: application MIME subtype name: adrl+xml Levin Expires May 1, 2004 [Page 9] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 Required parameters: None Optional parameters: charset See RFC 3023 [12] for a discussion of the charset parameter on XML-derived MIME types. Since this MIME type is used exclusively in SIP, the use of UTF-8 encoding is strongly encouraged. Encoding considerations: 8-bit text Security considerations: Security considerations specific to uses of this MIME type are discussed in RFC xxxx [[Note to RFC editor: replace xxxx with the RFC number of this document when published]]. RFC-1874 [4] and RFC-3023 [5] discuss security issues common to all uses of XML. Interoperability considerations: The use of this MIME body is intended to be generally interoperable. No unique considerations have been identified. Published specification: RFC xxxx [[Note to RFC editor: replace xxxx with the RFC number of this document when published]] Applications which use this media type: This media type is used to convey meta-information for the state of lists of resources within a Session Initiation Protocol (SIP) subscription. Additional information: Magic Number(s): None. File Extension(s): None. Macintosh File Type Code(s): None. Object Identifier(s) or OID(s): None. Intended usage: Limited Use Other Information/General Comment: None. Person to contact for further information: Name: Orit Levin E-Mail: oritl@microsoft.com Levin Expires May 1, 2004 [Page 10] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 7.3 URN Sub-Namespace URI: urn:ietf:params:xml:ns:adrl Description: This is the XML namespace URI for XML elements defined by [RFCXXXX] to describe identifiers of resources when the information about such resources is aggregated within a single SIP subscription. It is used in the application/adrl+xml body type. Registrant Contact: Name: Orit Levin E-Mail: oritl@microsoft.com XML: BEGIN Namespace for SIP Ad-hoc Resource List

Namespace for SIP Ad-hoc Resource List

application/adrl+xml

See RFCXXXX.

END 8. Acknowledgments Many thanks to Dhigha Sekaran and Sean Olson. Normative References [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levin Expires May 1, 2004 [Page 11] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 Levels", BCP 14, RFC 2119, March 1997. [3] Rosenberg, J., Schulzrinne, H. and P. Kyzivat, "Caller Preferences for the Session Initiation Protocol (SIP)", draft-ietf-sip-callerprefs-10 (work in progress), October 2003. Informational References [4] Levinson, E., "SGML Media Types", RFC 1874, December 1995. [5] Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC 3023, January 2001. [6] Sugano, H. and S. Fujimoto, "Presence Information Data Format (PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003. [7] Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work in progress), January 2003. [8] Roach, A., Rosenberg, J. and B. Campbell, "A Session Initiation Protocol (SIP) Event Notification Extension for Resource Lists", draft-ietf-simple-event-list-04 (work in progress), June 2003. [9] Lonnfors, M., "Partial Notification of Presence Information", draft-ietf-simple-partial-notify-00 (work in progress), September 2003. Author's Address Orit Levin Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA EMail: oritl@microsoft.com Levin Expires May 1, 2004 [Page 12] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 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 Levin Expires May 1, 2004 [Page 13] Internet-Draft Ad-hoc Resource Lists using SUBSCRIBE Nov 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Levin Expires May 1, 2004 [Page 14]