SIPPING Working Group G. Camarillo
Internet-Draft Ericsson
Expires: September 25, 2004 A. Roach
dynamicsoft
March 27, 2004
Subscriptions to Ad-Hoc Resource Lists in the Session Initiation
Protocol (SIP)
draft-camarillo-sipping-adhoc-simple-00.txt
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Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document describes how to create subscriptions to ad-hoc
resource lists in SIP. This is done by having the SUBSCRIBE request
that requests the creation of the subscription carry a URI list.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Providing a Resource List Server with a URI List . . . . . . . 3
4. URI List Format . . . . . . . . . . . . . . . . . . . . . . . 4
5. Resource List Server Behavior . . . . . . . . . . . . . . . . 4
6. Resource List Life-Time . . . . . . . . . . . . . . . . . . . 4
7. Providing a URI to Manipulate a Resource List . . . . . . . . 4
8. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6
10. Acknowledges . . . . . . . . . . . . . . . . . . . . . . . . . 6
Normative References . . . . . . . . . . . . . . . . . . . . . 6
Informational References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 6
Intellectual Property and Copyright Statements . . . . . . . . 8
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1. Introduction
Subscriptions to homogeneous resource lists in SIP [2] are described
in [3], which assumes that a resource list (i.e., a list of URIs) is
represented by a URI (generally a SIP URI). Once a UA obtains the URI
that represents a resource list, it can use the mechanisms described
in [3] to subscribe to it.
For example, let us assume that the resource list identified by the
SIP URI sip:my-friends@example.com contains the following URIs:
sip:bill@example.com
sip:joe@example.com
sip:ted@example.com
sip:bob@example.com
If a UA subscribes to the presece information of
sip:my-friends@example.com, it will obtain the presence information
of all the resources in the list.
In any case, [3] does not tackle list creation. This document
describes a way to create an ad-hoc list with a set of resources, and
subscribe to it, using a single SIP request. We use the mechanism to
carry URI lists in SIP messages described in [4].
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. Providing a Resource List Server with a URI List
A client that wants to create an ad-hoc resource list and subscribe
to it using the mechanism described in this document MUST add a
"list" parameter (defined in [4]) to the URI of the resource list and
MUST place the resulting URI in the Request-URI of a SUBSCRIBE. The
"list" parameter MUST contain a pointer to a URI list that contains
the URIs that belong to the resource list. The following is an
example of a Request-URI with a "list" parameter.
sip:rls@example.com;list="cid:cn35t8jf02@example.com"
The client MUST build the remaining of the SUBSCRIBE request
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following the rules in [3].
4. URI List Format
As described in [4], the default format for URI lists in SIP is the
XCAP resource list format [6]. Still, specific services need to
describe which information clients should include in their URI lists,
as described in [4].
UAs subscribing to an ad-hoc resource list SHOULD use flat lists
(i.e., no hierarchical lists), SHOULD NOT use any entry's attributes
but "uri", and SHOULD NOT include any elements inside entries but
"display-name" elements.
Resource list servers receiving a URI list with more information than
what we have just described SHOULD discard all the extra information.
5. Resource List Server Behavior
On reception of a SUBSCRIBE with a URI list as described in Section
3, a resource list server MUST follow the rules described in [3] to
create the subscription, using the URI list just received as the
resource list for the subscription.
Once the resource list server has created the subscription, it
behaves as a regular resource list server and MUST follow the rules
in [3].
Note that the status code in the response to the SUBSCRIBE does not
provide any information about whether or not the resource list server
was able to succesfully subscribe to the URIs in the URI list. The
client obtains this information in the NOTIFIES sent by the server.
6. Resource List Life-Time
The life-time of a resource list created as described in Section 5 is
blundled to the life-time of the subscription. That is, the resource
list SHOULD be destroyed when the subscription expires or is
otherwise terminated.
7. Providing a URI to Manipulate a Resource List
A client may need to manipulate a resource list at a resource list
server. The resource list server MAY provide a URI to manipulate the
resource list associated with a subscription using the Call-Info
header field [5] in the NOTIFY that establishes the subscription. The
"purpose" parameter of the Call-Info header field MUST have a value
of "list-management". The following is an example of such a header
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field.
Call-Info: <http://xcap.example.com/your-list.xml>
;purpose=list-management
8. Example
The following is an example of a SUBSCRIBE request, which carries a
URI list in its body, sent by a UA to a resource list server.
SUBSCRIBE sip:rls@example.com;list=cid:cn35t8jf02@example.com SIP/2.0
Via: SIP/2.0/TCP terminal.example.com;branch=z9hG4bKwYb6QREiCL
Max-Forwards: 70
To: RLS <sip:rls@example.com>
From: <sip:adam@example.com>;tag=ie4hbb8t
Call-ID: cdB34qLToC@terminal.example.com
CSeq: 1 SUBSCRIBE
Contact: <sip:terminal.example.com>
Event: presence
Expires: 7200
Supported: eventlist
Accept: application/cpim-pidf+xml
Accept: application/rlmi+xml
Accept: multipart/related
Accept: multipart/signed
Accept: multipart/encrypted
Content-Type: application/resource-lists+xml
Content-Length: 315
Content-ID: <cn35t8jf02@example.com>
<?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list>
<entry uri="sip:bill@example.com" />
<entry uri="sip:joe@example.com" />
<entry uri="sip:ted@example.com" />
<entry uri="sip:bob@example.com" />
</list>
</resource-lists>
Figure 1: SUBSCRIBE request
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9. Security Considerations
TBD
10. Acknowledges
Cullen Jennings provided useful comments on this document.
Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] 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.
[3] 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.
[4] Camarillo, G., "Providing a Session Initiation Protocol (SIP)
Application Server with a List of URIs",
draft-camarillo-sipping-uri-list-01 (work in progress), February
2004.
[5] Khartabil, H., "Conveying a Session Policy Uniform Resource
Identifier (URI) in the Session Initiation Protocol (SIP)",
draft-khartabil-sip-policy-uri-call-info-purpose-00 (work in
progress), February 2004.
Informational References
[6] Rosenberg, J., "An Extensible Markup Language (XML)
Configuration Access Protocol (XCAP) Usage for Presence Lists",
draft-ietf-simple-xcap-list-usage-02 (work in progress),
February 2004.
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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
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