SIPPING Working Group G. Camarillo Internet-Draft Ericsson Expires: August 6, 2004 A. Roach dynamicsoft February 6, 2004 Providing a Session Initiation Protocol (SIP) Application Server with a List of URIs draft-camarillo-sipping-uri-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 August 6, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document describes how a user agent can provide an application server with a list of URIs. The way the application server uses the URIs in the list is service specific. Camarillo & Roach Expires August 6, 2004 [Page 1] Internet-Draft URI Lists in SIP February 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. URI Parameter vs. Header Field . . . . . . . . . . . . . . . . 3 4. The SIP and SIPS URI List Parameter . . . . . . . . . . . . . 4 5. Ad-Hoc List' Life Time . . . . . . . . . . . . . . . . . . . . 4 6. The Content-ID SIP Header Field . . . . . . . . . . . . . . . 4 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1 Ad-Hoc Conference . . . . . . . . . . . . . . . . . . . . . . 5 7.2 Presence List . . . . . . . . . . . . . . . . . . . . . . . . 7 8. Security Considerations . . . . . . . . . . . . . . . . . . . 7 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 Normative References . . . . . . . . . . . . . . . . . . . . . 8 Informational References . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . 10 Camarillo & Roach Expires August 6, 2004 [Page 2] Internet-Draft URI Lists in SIP February 2004 1. Introduction The need for exploders in SIP is described in [7]. Mechanisms to invoke exploders in SIP need to meet the requirements listed there. UAs need to have a means to provide application servers with a set of URIs for certain services. For example, a UA creating a conference needs to provide the conference server with the participants. The same way, a UA requesting presence information from a set of users needs to provide the resource list server with the URIs of the users that belong to the list. These lists are typically configured using out-of-band methods. For instance, a UA can use XCAP [6] to create a list of URIs and to associate this list with a SIP URI. It can, then, send a SIP request (an INVITE or a SUBSCRIBE in our previous examples) to that SIP URI. Still, there is a need to create lists of URIs in an ad-hoc way and send them directly in a SIP message. We define a SIP and SIPS URI paramerer called "list", which carries a URI. This URI is a pointer to a URI list. A UA creating a SIP request that needs to carry a URI list proceeds this way. It places the URI list (e.g., an XCAP resource list [4]) in a body part, and then, it adds a "list" parameter to the Request-URI. This "list" parameter contains a Content-ID URL [2] that points to the body part that carries the URI list. Alternatively, the URI in the "list" parameter can point to an external URI list (e.g., an http URI). In this case, the URI list would not be carried in the SIP request. The way the application server interprets the URI list received in the request is service specific. 2. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [1] and indicate requirement levels for compliant implementations. 3. URI Parameter vs. Header Field We have chosen to transport the pointer to the URI list in a URI parameter rather than in a header field because, this way, the Request-URI fully indentifies the service being invoked and all the Camarillo & Roach Expires August 6, 2004 [Page 3] Internet-Draft URI Lists in SIP February 2004 recipients of the service. Using a header field instead would imply that the Request-URI did not carry the list of the reciptiens. Network administrators should note that they need to configure proxies to route correctly Request-URIs that contain a "list" parameter and are addressed to their domain. 4. The SIP and SIPS URI List Parameter We define the "list" parameter for SIP and SIPS URIs. It MUST contain a URI that points to a URI list. The XCAP resource list format [4] MUST be supported; any other URI list formats MAY be supported. The ABNF of the "list" parameter is: list-param = "list=" absoluteURI The following is an example of a SIP URI with a list parameter pointing to a body part using a Content-ID URL [2]: sip:group@example.com;list=cid:cn35t8jf02@example.com The following is an example of a SIP URI with a list parameter pointing to an external URI: sip:group@example.com;list=http://xcap.example.com/lists/mylist.xml 5. Ad-Hoc List' Life Time An application server that receives a request with a URI list (or a pointer to it) creates a so called ad-hoc list, whose lifetime depends on the service provided by the server. Ad-Hoc lists created by requests that do not establish a dialog usually expire immediately. Ad-Hoc lists created by requests that establish a dialog usually expire when the dialog terminates. 6. The Content-ID SIP Header Field The Content-ID MIME header field is defined in RFC 2045 [5]. We define here the same header field to be used in SIP messages. Its ABNF is: Content-ID = "Content-ID" HCOLON msg-id RFC 2822 [3] defines msg-id in Section 3.6.4. The Content-ID value is used to uniquely identify a body or a body part. The Content-ID header field MAY appear in any SIP request or Camarillo & Roach Expires August 6, 2004 [Page 4] Internet-Draft URI Lists in SIP February 2004 response that contains a body. 7. Examples This section shows how to use the list parameter to create an ad-hoc conference and to subscribe to the presence information to a set of users. These examples illustrate the usage of the "list" parameter. They do not mandate how the previously mentioned services have to be implemented. 7.1 Ad-Hoc Conference Carol creates an ad-hoc conference by sending the INVITE request shown in Figure 1. The list parameter in the Request-URI points to a MIME body that carries the list of participants. INVITE sip:ad-hoc@example.com;list=cid:cn35t8jf02@example.com SIP/2.0 Via: SIP/2.0/TCP client.chicago.example.com ;branch=z9hG4bKhjhs8ass83 Max-Forwards: 70 To: "Ad-Hoc Conferences" From: Carol ;tag=32331 Call-ID: d432fa84b4c76e66710 CSeq: 1 INVITE Contact: Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow-Events: dialog Accept: application/sdp, message/sipfrag, application/resource-lists+xml Conten-Type: multipart/mixed;boundary="boundary1" Content-Length: 731 --boundary1 Content-Type: application/sdp Content-Length: 160 v=0 o=carol 2890844526 2890842807 IN IP4 chicago.example.com s=Example Subject c=IN IP4 192.0.0.1 t=0 0 m=audio 20000 RTP/AVP 0 m=video 20002 RTP/AVP 31 --boundary1 Content-Type: application/resource-lists+xml Camarillo & Roach Expires August 6, 2004 [Page 5] Internet-Draft URI Lists in SIP February 2004 Content-Length: 367 Content-ID: --boundary1-- Figure 1: INVITE request SIP/2.0 200 OK Via: SIP/2.0/TCP client.chicago.example.com ;branch=z9hG4bKhjhs8ass83;received=192.0.2.4 To: "Ad-Hoc Conferences" ;tag=733413 From: Carol ;tag=32331 Call-ID: d432fa84b4c76e66710 CSeq: 1 INVITE Contact: ;isfocus Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow-Events: dialog, conference Accept: application/sdp, application/conference-info+xml, application/resource-lists+xml, message/sipfrag Supported: replaces, join Content-Type: application/sdp Content-Length: 312 v=0 o=focus431 2890844526 2890842807 IN IP4 ms5.conf.example.com s=Example Subject i=Example Conference Hosted by Example.com u=http://conf.example.com/3402934234 e=3402934234@conf-help.example.com p=+1-888-555-1212 c=IN IP4 ms5.conf.example.com t=0 0 m=audio 49170 RTP/AVP 0 m=video 51372 RTP/AVP 31 Figure 2: 200 (OK) response Camarillo & Roach Expires August 6, 2004 [Page 6] Internet-Draft URI Lists in SIP February 2004 The conference server responds with a 200 (OK) that carries the URI for the conference in its Contact header field. If the UA wants to obtain information about the status of the conference, for instance, it will SUBSCRIBE to the conference package using this URI. 7.2 Presence List Carol subscribes to the presence information of four of her friends using the list parameter. SUBSCRIBE sip:ad-hoc@example.com;list=cid:cn35t8jf02@example.com SIP/2.0 Via: SIP/2.0/TCP client.chicago.example.com ;branch=z9hG4bKhjhs8ass83 Max-Forwards: 70 To: "Ad-Hoc Presence List" From: Carol ;tag=32331 Call-ID: d432fa84b4c76e66710 CSeq: 1 INVITE Contact: Require: eventlist Event: presence Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow-Events: presence Accept: application/sdp, message/sipfrag, application/resource-lists+xml, application/rlmi+xml Content-Type: application/resource-lists+xml Content-Length: 367 Content-ID: Figure 3: SUBSCRIBE request 8. Security Considerations TBD. Camarillo & Roach Expires August 6, 2004 [Page 7] Internet-Draft URI Lists in SIP February 2004 9. IANA Considerations This document registers the "list" SIP and SIPS URI parameter, which is described in Section 4. This parameter is to be added to the SIP and SIPS URI parameter registry under http://www.iana.org/ TBD. This document registers the Content-ID SIP header field, which is described in Section 6. This header field is to be added to the header field registry under http://www.iana.org/assignments/ sip-parameters. Header Name: Content-ID Compact Form: (none) Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Levinson, E., "Content-ID and Message-ID Uniform Resource Locators", RFC 2392, August 1998. [3] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [4] Rosenberg, J., "An Extensible Markup Language (XML) Configuration Access Protocol (XCAP) Usage for Presence Lists", draft-ietf-simple-xcap-list-usage-01 (work in progress), October 2003. Informational References [5] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [6] Rosenberg, J., "The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)", draft-ietf-simple-xcap-01 (work in progress), October 2003. [7] Camarillo, G., "Requirements for Session Initiation Protocol (SIP) Exploder Invocation", draft-camarillo-sipping-exploders-01 (work in progress), November 2003. Camarillo & Roach Expires August 6, 2004 [Page 8] Internet-Draft URI Lists in SIP February 2004 Authors' Addresses Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland EMail: Gonzalo.Camarillo@ericsson.com Adam Roach dynamicsoft 5100 Tennyson Pkwy Suite 1200 Plano, TX 75024 US EMail: adam@dynamicsoft.com Camarillo & Roach Expires August 6, 2004 [Page 9] Internet-Draft URI Lists in SIP February 2004 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. 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