Sipping P. Kyzivat
Internet-Draft Cisco Systems, Inc.
Expires: April 6, 2005 October 6, 2004
Reg Event Package Extension for GRUUs
draft-kyzivat-sipping-gruu-reg-event-01
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Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
This draft defines an extension to RFC 3680 [1] for representing the
GRUU associated with a Contact.
1. Introduction
The addition of GRUU (Globally Routable Unique URI) support to the
REGISTER message, defined in [2], introduces another element of state
to the registrar. Subscribers to the registration event package [1]
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will sometimes have need for the new state.
For example, the Welcome Notices example in [1] will only operate
correctly if the contact address in the reg event notification is
reachable by the sender of the welcome notice. When the registering
device is using the gruu extension, it is likely that the registered
contact address will not be globally addressable, and the gruu should
be used as the target address for the MESSAGE.
The reg event package has provision for including extension elements
within the <contact> element. This document defines a new element
that may be used in that context to deliver the GRUU corresponding to
the contact.
2. Description
A new element (<gruu>) is defined which contains a GRUU.
This optional element is included within the body of a NOTIFY for the
"reg" event package when a GRUU is associated with the contact. The
contact URI and the GRUU are then both available to the watcher.
3. Notifier Processing of SUBSCRIBE Requests
Unchanged from RFC 3680 [1].
4. Notifier Generation of NOTIFY Requests
A notifier for the "reg" event package [1] SHOULD include the <gruu>
element when a contact has an Instance ID and a GRUU is associated
with the combination of the AOR and the Instance ID. When present,
the <gruu> element MUST be be positioned as an instance of the <any>
element within the <contact> element.
5. Subscriber Processing of NOTIFY Requests
When a subscriber receives a "reg" event notification [1] with a
<contact> containing a <gruu>, it SHOULD use the gruu in preference
to the corresponding <uri> when sending SIP requests to the contact.
Subscribers that are unaware of this extension will, as required by
[1], ignore the <gruu> element.
6. Sample reginfo Document
The following is an example registration information document
including the new element:
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<?xml version="1.0"?>
<reginfo xmlns="urn:ietf:params:xml:ns:reginfo"
xmlns:gr="urn:ietf:params:xml:ns:gruu"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
version="0" state="full">
<registration aor="sip:user@example.com" id="as9"
state="active">
<contact id="76" state="active" event="registered"
duration-registered="7322"
q="0.8">
<uri>sip:user@192.0.2.1</uri>
<unknown-param name="+sip.instance">
"<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>"
</unknown-param>
<gr:gruu>sip:hha9s8d=-999a@example.com</gruu>
</contact>
</registration>
</reginfo>
7. Example: Welcome Notice
Consider the Welcome Notices example in [1]. When the application
server receives a notification of a new registration containing the
reginfo shown in Section 6 it should address messages using the
contained GRUU as follows:
MESSAGE sip:hha9s8d=-999a@example.com SIP/2.0
To: <sip:hha9s8d=-999a@example.com>
From: "SIPland Notifier" <sip:notifier@example.com>
Content-Type: text/plain
Content-Length: ...
Welcome to SIPland!
Blah, blah, blah.
8. XML Schema Definition
A gruu document is an XML document that MUST be well-formed and
SHOULD be valid. Gruu documents MUST be based on XML 1.0 and MUST be
encoded using UTF-8. This specification makes use of XML namespaces
for identifying gruu documents. The namespace URI for elements
defined for this purpose is a URN, using the namespace identifier
'ietf'. This URN is:
urn:ietf:params:xml:ns:gruu
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<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:ietf:params:xml:ns:gruu"
elementFormDefault="qualified"
attributeFormDefault="unqualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:tns="urn:ietf:params:xml:ns:gruu">
<xs:element name="gruu" type="xs:anyURI"/>
</xs:schema>
9. IANA Considerations
This section registers a new XML namespace, as per the guidelines in
[3].
URI: The URI for this namespace is
urn:ietf:params:xml:ns:gruu
Registrant Contact: TBD
XML: TBD
10. Security Considerations
Security considerations for the registration event package is
discussed in RFC 3680 [1], and those considerations apply here.
The addition of gruu information does not impact security negatively
because the gruu is less sensitive than the contact URI itself.
11. Acknowledgements
The author would like to thank Jonathan Rosenberg for encouraging
this draft.
12. References
12.1 Normative References
[1] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Registrations", RFC 3680, March 2004.
[2] Rosenberg, J., "Obtaining and Using Globally Routable User Agent
(UA) URIs (GRUU) in the Session Initiation Protocol (SIP)",
draft-ietf-sip-gruu-02 (work in progress), July 2004.
[3] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January
2004.
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12.2 Informative References
[4] 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.
Author's Address
Paul H. Kyzivat
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA
EMail: pkyzivat@cisco.com
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