SIPPING Working Group G. Camarillo
Internet-Draft Ericsson
Expires: August 6, 2004 February 6, 2004
Ad-Hoc URI List Management in the Session Initiation Protocol (SIP)
draft-camarillo-sipping-adhoc-management-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document defines two mechanisms to manage ad-hoc URI lists in
SIP. In the first mechanism, the user agent sends an updated version
of the entire list to the server. In the second mechanism, the server
provides the user agent with a URI (e.g., http) that can be used to
manipulate the list using an out-of-band mechanim (e.g., XCAP). We
define the Associated-List-Manipulation header field that carries a
URI that allows manipulating an ad-hoc list.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. List Substitution . . . . . . . . . . . . . . . . . . . . . . 3
4. Out-of-Band Management . . . . . . . . . . . . . . . . . . . . 3
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1 List Substitution . . . . . . . . . . . . . . . . . . . . . . 6
5.2 Out-of-Band Management . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
Normative References . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . 9
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1. Introduction
SIP messages can carry URI lists using the "list" SIP and SIPS URI
parameter defined in [3]. An application server receiving a SIP
request with a URI list creates a so called ad-hoc URI list, which is
valid for the duration of the service provided by the server.
Once an ad-hoc URI list is created at the server, the user agent may
need to manipulate it (e.g., add URIs to the list and remove URIs
from the list). Section 3 and Section 4 describe two methods to
perform ad-hoc URI list management.
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. List Substitution
A user agent MAY provide an application server with an updated
version of the ad-hoc list by sending a request with a "list"
parameter [3] in its Request-URI. The "list" parameter MUST contain a
pointer to the updated list. (The method of this request depends on
the service being delivered.) On reception of such a request, the
application server MUST substitute the previous ad-hoc list with the
list referenced by the "list" parameter.
4. Out-of-Band Management
Section 3 describes how to send a complete URI list to an application
server that substitutes the previous one. Following this approach, a
user agent that wants to modify a single URI in a long URI list needs
to resend the whole list.
Still, there are URI list management mechanisms, such as the XCAP
usage defined in [2], that allow user agents to manipulate URI lists
more efficiently. We define a new SIP header field called
Associated-List-Manipulation that allows a server to provide a URI to
the client to manipulate the ad-hoc list using an out-of-band
mechanism. The XCAP Usage for Resource Lists MUST be supported. Other
mechanisms MAY be supported.
The ABNF of the Associated-List-Manipulation header field is:
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List-Manipulation = "Associated-List-Manipulation" HCOLON
absoluteURI
5. Examples
This section shows how to use the mechanisms described in Section 3
and Section 4 to manipulate the list of participants in an ad-hoc
conference. This example illustrates the use of both mechanisms. It
does not mandate how ad-hoc conference services have to be
implemented.
When the ad-hoc conferencing server in this example receives an
initial INVITE with a URI list, it sends out an INVITE to each URI in
the list and creates an ad-hoc conference with all of them. If, at a
later point, a URI is added to the list, the conference server
INVITEs the new user. If a URI is removed from the list, the
conference server BYEs the user.
Carol creates an ad-hoc conference on the server 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" <sip:ad-hoc@example.com>
From: Carol <sip:carol@chicago.example.com>;tag=32331
Call-ID: d432fa84b4c76e66710
CSeq: 1 INVITE
Contact: <sip:carol@client.chicago.example.com>
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
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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
Content-Length: 367
Content-ID: <cn35t8jf02@example.com>
<?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list name="ad-hoc-1">
<entry name="1" uri="sip:bill@example.com" />
<entry name="2" uri="sip:joe@example.com" />
<entry name="3" uri="sip:ted@example.com" />
<entry name="4" uri="sip:bob@example.com" />
</list>
</resource-lists>
--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" <sip:ad-hoc@example.com>;tag=733413
From: Carol <sip:carol@chicago.example.com>;tag=32331
Call-ID: d432fa84b4c76e66710
CSeq: 1 INVITE
Contact: <sip:34@example.com>;isfocus
Associated-List-Manipulation: http://xcap.example.com/lists/yourlist
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
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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
The conference server responds with the 200 (OK) in Figure 1, which
carries the URI for the conference in its Contact header field and a
URI for manipulating the URI list in its Associated-List-Manipulation
header field.
5.1 List Substitution
Carol wants to remove Bill and Joe from the conference. She sends the
re-INVITE in Figure 3 to the conference server with an updated URI
list in a "list" parameter.
INVITE sip:34@example.com;isfocus;list=cid:cn35t8j@example.com SIP/2.0
Via: SIP/2.0/TCP client.chicago.example.com
;branch=z9hG4bKhjhs8ass83
Max-Forwards: 70
To: "Ad-Hoc Conferences" <sip:ad-hoc@example.com>
From: Carol <sip:carol@chicago.example.com>;tag=32331
Call-ID: d432fa84b4c76e66710
CSeq: 2 INVITE
Contact: <sip:carol@client.chicago.example.com>
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: xxx
--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
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m=video 20002 RTP/AVP 31
--boundary1
Content-Type: application/resource-lists+xml
Content-Length: xxx
Content-ID: <cn35t8j@example.com>
<?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list name="ad-hoc-1">
<entry name="3" uri="sip:ted@example.com" />
<entry name="4" uri="sip:bob@example.com" />
</list>
</resource-lists>
--boundary1--
Figure 3: Re-INVITE
5.2 Out-of-Band Management
Now, Carol wants to add Alice to the conference. This time, she uses
the http URI received in the Associated-List-Manipulation header
field. She uses XCAP to add Alice's URI, so no SIP traffic is
exchanged between her and the server.
6. Security Considerations
TBD.
7. IANA Considerations
This document registers the Associated-List-Manipulation SIP header
field, which is described in Section 4. This header field is to be
added to the header field registry under http://www.iana.org/
assignments/sip-parameters.
Header Name: Associated-List-Manipulation
Compact Form: (none)
8. Acknowledgments
Adam Roach, Jonathan Rosenberg, and Orit Levin provided useful
comments on this document.
Normative References
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[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] 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.
[3] Camarillo, G., "Providing a Session Initiation Protocol (SIP)
Application Server with a List of URIs",
draft-camarillo-sipping-uri-list-00 (work in progress), November
2003.
Author's Address
Gonzalo Camarillo
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
EMail: Gonzalo.Camarillo@ericsson.com
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