WG Review: Extensible Messaging and Presence Protocol (xmpp)

[IESG Secretary <[e-mail]>]

A new IETF working group has been proposed in the Real-time Applications
and Infrastructure Area.  The IESG has not made any determination as yet.
The following draft charter was submitted, and is provided for
informational purposes only.  Please send your comments to the IESG
mailing list ([e-mail]) by Tuesday, May 19, 2009.


Extensible Messaging and Presence Protocol (xmpp)
-------------------------------------------------

Last Modified: 2009-04-27

Current Status: Proposed Working Group

Chair(s):
TBD

Area Director(s):
Robert Sparks <[e-mail]>
Cullen Jennings <[e-mail]>

Area Advisor:
TBD

Mailing Lists:
General Discussion: [e-mail]

Description of Working Group:

The Extensible Messaging and Presence Protocol (XMPP) is an
technology for the near-real-time exchange of messages and presence
notifications, where data is exchanged over Extensible Markup Language
(XML) streams. XMPP was originally formalized by the XMPP Working Group
in 2002-2004, resulting in publication of RFCs 3920-3923.

Implementation and deployment experience since that time has resulted
in errata, clarifications, and suggestions for improvement to the core
XMPP specifications (RFCs 3920 and 3921). Some technologies on which
XMPP depends (e.g., Transport Layer Security and the Simple
Authentication and Security Layer) have undergone modifications of their
own, which XMPP needs to track. Finally, the group needs to define a
sustainable solution to internationalization of XMPP addresses, since
the approach taken in RFC 3920 (based on stringprep profiles) is limited
to Unicode 3.2 characters. Both draft-saintandre-rfc3920bis-* and
draft-saintandre-rfc3921bis-* reflect community input so
far regarding these modifications, but the group needs to complete this
work, especially with regard to internationalization. Because of the
scope of changes involved, it is envisioned that these specifications
will be cycled at Proposed Standard.

Although RFC 3923 defines an end-to-end signing and encryption
technology for use by XMPP systems, to date it has not been implemented.
A goal of the group is to develop an implementable method for end-to-end
encryption, preferably based on well known and widely deployed security
technologies.

XMPP uses TLS for encryption and the Simple Authentication and Security
Layer (SASL) for authentication. In the case of a server-to-server
stream, XMPP is deployed using TLS and the SASL EXTERNAL mechanism,
where each peer presents an X.509 certificate. This model introduces
scaling challenges in multi-domain deployments because RFC 3920 requires
that a stream cannot be reused for more than one domain, thus
necessitating multiple TCP connections. The group will work to overcome
these challenges by defining an optional mechanism for using a single
connection with multiple identities. It is anticipated that most of the
work will consist of defining and providing requirements to the TLS and
SASL working groups.

Many of the core and extended features of XMPP have also been
implemented in technologies based on the Session Initiation Protocol
(SIP). To ensure interworking between XMPP systems and SIP systems, a
number of Internet-Drafts (draft-saintandre-sip-xmpp-*) have been
produced. The group will define a framework within which this work could
be completed.

In completing its work, the group will strive to retain backwards
compatibility with RFCs 3920 and 3921. However, changes that are not
backwards compatible might be accepted if the group determines that the
changes are required to meet the group's technical objectives and the
group clearly documents the reasons for making them.


Goals and Milestones:

- Deliver rfc3920bis and rfc3921bis to the IESG.

- Decide upon a direction for end-to-end encryption.

- Decide upon a direction for server-to-server connection reuse.

- Define a framework for SIP-XMPP interworking.

- Define a solution for end-to-end encryption.

- Define a solution for server-to-server connection reuse.