One document matched: draft-mahy-impp-unified-proposal-00.txt
IMPP WG R. Mahy, Ed.
Internet-Draft Cisco Systems
Expires: July 27, 2004 January 27, 2004
A Unified Proposal for Server-to-Server Presence and Instant
Messaging
draft-mahy-impp-unified-proposal-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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This Internet-Draft will expire on July 27, 2004.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
Standardization of Instant Message and Presence Protocols in the IETF
has resulted in multiple protocols. There are significant industry
and technical advantages to standardizing a unified approach for
server-to-server Instant Messaging and Presence. This document
proposes a server profile which uses SIP to exchange presence and
setup sessions, and XMPP for message transport.
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Table of Contents
1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Proposal Overview . . . . . . . . . . . . . . . . . . . . . . 3
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1 Exchanging Instant Messages . . . . . . . . . . . . . . . . . 4
4.2 Exchanging Presence Data . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
Normative References . . . . . . . . . . . . . . . . . . . . . 10
Informational References . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . 13
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1. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [1].
2. Problem Statement
The authors of this document believe that a unified approach for
server-to-server Instant Messaging and Presence offers significant
technical and industry advantages. The IM and Presence industry is
currently fragmented. Having two IETF protocols for IM and Presence
with no additional guidance on the use of these protocols is
confusing to the industry, and until the IETF provides leadership
and guidance in this area, it is unlikely that any significant
percentage of Instant Messaging traffic will use interoperable
systems. We believe that a profile which describes the use of SIP [4]
and XMPP [2] for server-to-server interoperability provides the
guidance the industry needs in a way which is mutually beneficial to
both communities, and naturally uses the core strengths of each
protocol. We refer to this combined system as UMPP (Unified Messaging
and Presence Profile).
3. Proposal Overview
UMPP UMPP
Server Server
.............. ..............
. +--------+ . session setup. +--------+ .
Clients ---. | SIP | .<----SIP----->. | SIP | .---- Clients
. | Server | . presense . | Server | .
. +--------+ . . +--------+ .
Clients ---. . . .---- Clients
. +--------+ . . +--------+ .
. | XMPP | . message . | XMPP | .
. | Host | .<====XMPP====>. | Host | .
Clients ---. +--------+ . transport . +--------+ .---- Clients
.............. ..............
A UMPP Server consists of a cooperating SIP Server and an XMPP Host,
which provide basic server-to-server instant messaging and presence.
While additional capabilities could be added in the future, the focus
is on basic functionality to solve a very pressing interoperability
problem. UMPP Servers talk to other UMPP Servers using SIP and XMPP,
and to their clients using whatever protocol they would like. A UMPP
Server can support communities of XMPP-only clients, SIMPLE-only
clients, and/or clients using proprietary protocols for example.
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A series of XMPP "chat" or "groupchat" messages (for example a
thread) can be viewed as a session. UMPP SIP servers exchange offers
and answers [6] for sessions of XMPP IM [3] messages. When one domain
wishes to send an IM to another, it issues a standard SIP invitation
to establish an IM session between them. The session descriptions in
the appropriate SIP messages contain XMPP identifiers (JIDs) to
identify where the messages are to be sent. These messages can be
protected end-to-end using the XMPP e2e tag [12]
This approach combines the best of what SIP and XMPP have to offer.
SIP's session mode allows IM to work in exactly the same way as
voice, video, and other communications modalities [14]. XMPP's
lightweight transport and congestion control properties make it ideal
for carrying the actual messages.
Presence data in the IMPP Presence Information Data Format (PIDF [9])
format is exchanged using subscriptions [7] to the SIP presence [8]
event package. When a user in one domain wishes to obtain presence
information from a user in another domain, the server in the
originating domain issues a SIP SUBSCRIBE request. Presence data is
then delivered in NOTIFY messages sent from the domain of the
presentity.
One of the complexities in providing a server to server protocol that
works across different intra-domain IM technologies is naming. SIP
uses the SIP URI for addressing, and XMPP uses the JID (XMPP
Identifier). UMPP servers use im: [10] and pres: [11] URIs as
universal identifiers for initial addressing (SIP addresses-of-record
and bare XMPP JIDs are not used). SIP contact URIs are exchanged in
Contact headers, and fully-qualified JIDs are exchanged in session
descriptions and in XMPP messages. UMPP servers can use the
procedures defined in [13] or local resolution procedures to locate
the appropriate server for im: and pres: URIs. This is similar to how
addressing works in email systems, where the universal user@domain
identifier is mapped to local identifiers used by mail systems in
each domain.
4. Examples
The examples in the following section omit portions of SIP messages
and XMPP streams for brevity and clarity. Specifically SIP Via,
Max-Forwards, and Content-Length headers are omitted; and initial
XMPP stream setup with TLS and SASL is omitted.
4.1 Exchanging Instant Messages
When a client represented by one UMPP Server (Romeo) wants to send
messages to a client represented by another UMPP Server (Juliet),
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Romeo's UMPP Server sends a SIP invitation to Juliet's UMPP Server.
The servers exchange fully qualified JIDs (XMPP identifiers), and
then send XMPP messages. When the session is over, either server
sends a SIP BYE request.
example.net example.com
UMPP Sever UMPP Server
(Romeo) (Juliet)
| |
|----SIP INVITE--------------------------->|
|<---SIP 200 OK----------------------------|
|----SIP ACK------------------------------>|
|====XMPP message 1=======================>|
| |
| |
|<===XMPP message 2========================|
| |
| |
|====XMPP message 3=======================>|
| |
| |
|<---SIP BYE-------------------------------|
|----SIP 200 OK--------------------------->|
| |
| |
SIP Message 1:
INVITE im:juliet@thecappulets.example.com SIP/2.0
To: Juliet <im:juliet@thecappulets.example.com>
From: Romeo <im:romeo@montague.example.net>;tag=29923923
Call-ID: 2349098234@orchard.montague.example.net
CSeq: 13992 INVITE
Contact: <sip:romeo@orchard.montague.example.net>
Content-Type: application/sdp
Content-Length: (appropriate value)
v=0
o=romeo 289087 289087 IN IP4 orchard.montague.example.net
s=-
c=IN IP4 orchard.montague.example.net
t=0 0
m=audio 39923 RTP/AVP 0
a=rtpmap:0 PCMU/8000
c=IN IP4 xmpp.montague.example.net
t=0 0
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m=message 5222 xmpp/tcp chat
a=direction:both
a=jid:romeo@montague.example.net/orchard
a=thread:283461923759234
SIP Message 2 :
SIP/2.0 200 OK
To: Juliet <im:juliet@thecappulets.example.com>;tag=939231235
From: Romeo <im:romeo@montague.example.net>;tag=29923923
Call-ID: 2349098234@orchard.montague.example.net
CSeq: 13992 INVITE
Contact: <sip:juliet@balcony.thecappulets.example.com>
Content-Type: application/sdp
Content-Length: (appropriate value)
v=0
o=juliet 289087 289087 IN IP4 balcony.thecappulets.example.com
s=-
c=IN IP4 balcony.thecappulets.example.com
t=0 0
m=audio 0 RTP/AVP 0
a=rtpmap:0 PCMU/8000
c=IN IP4 impish.thecapulets.example.com
t=0 0
m=message 5222 xmpp/tcp chat
a=direction:passive
a=jid:juliet@thecappulets.example.com/balcony
SIP Message 3 :
ACK sip:juliet@balcony.thecappulets.example.com SIP/2.0
To: Juliet <im:juliet@thecappulets.example.com>;tag=939231235
From: Romeo <im:romeo@montague.example.net>;tag=29923923
Call-ID: 2349098234@orchard.montague.example.net
CSeq: 13992 ACK
XMPP Stanza 1:
<message
to="romeo@montague.example.net/orchard"
from="juliet@thecappulets.example.com/balcony"
type="chat">
<body>Art thou not Romeo, and a Montague?</body>
<thread>283461923759234</thread>
</message>
XMPP Stanza 2:
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<message
to="juliet@thecappulets.example.com/balcony"
from="romeo@montague.example.net/orchard"
type="chat">
<body>Neither, fair saint, if either thee dislike.</body>
<thread>283461923759234</thread>
</message>
XMPP Stanza 3:
<message
to="romeo@montague.example.net/orchard"
from="juliet@thecappulets.example.com/balcony"
type="chat">
<body>How cam'st thou hither, tell me, and wherefore?</body>
<thread>283461923759234</thread>
</message>
SIP Message 4:
BYE sip:romeo@orchard.montague.example.net SIP/2.0
From: Juliet <im:juliet@thecappulets.example.com>;tag=939231235
To: Romeo <im:romeo@montague.example.net>;tag=29923923
Call-ID: 2349098234@orchard.montague.example.net
CSeq: 33903 BYE
SIP Message 5:
SIP/2.0 200 OK
From: Juliet <im:juliet@thecappulets.example.com>;tag=9392312353
To: Romeo <im:romeo@montague.example.net>;tag=29923923
Call-ID: 2349098234@orchard.montague.example.net
CSeq: 33903 BYE
4.2 Exchanging Presence Data
When a client represented by one UMPP Server (Romeo) wants to
subscribe to presence data of a client represented by another UMPP
Server (Juliet), Romeo's UMPP Server sends a SIP subscription to the
presence event package to Juliet's UMPP Server. Juliet's presence
state arrives in notifications in the PIDF document format.
example.net example.com
UMPP Sever UMPP Server
(Romeo) (Juliet)
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| |
|----SIP SUBSCRIBE------------------------>|
|<---SIP 200 OK----------------------------|
|----SIP NOTIFY (status is open)---------->|
|<---SIP 200 OK----------------------------|
| |
| time passes.... |
| |
| |
|----SIP NOTIFY (status is closed)-------->|
|<---SIP 200 OK----------------------------|
| |
| |
SIP Message 1:
SUBSCRIBE pres:juliet@thecappulets.example.com SIP/2.0
To: Juliet <pres:juliet@thecappulets.example.com>
From: Romeo <pres:romeo@montague.example.net>;tag=23923
Call-ID: 98394813@orchard.montague.example.net
CSeq: 13667 SUBSCRIBE
Event: presence
Expires: 3600
Contact: <sip:romeo@orchard.montague.example.net>
SIP Message 2 :
SIP/2.0 200 OK
To: Juliet <pres:juliet@thecappulets.example.com>;tag=-938413
From: Romeo <pres:romeo@montague.example.net>;tag=23923
Call-ID: 98394813@orchard.montague.example.net
CSeq: 13667 SUBSCRIBE
Subscription-State: active;expires=3600
Contact: <sip:juliet@balcony.thecappulets.example.com>
SIP Message 3 :
NOTIFY sip:romeo@orchard.montague.example.net SIP/2.0
To: Romeo <pres:romeo@montague.example.net>;tag=23923
From: Juliet <pres:juliet@thecappulets.example.com>;tag=-938413
Call-ID: 98394813@orchard.montague.example.net
CSeq: 66734 NOTIFY
Subscription-State: active;expires=3600
Contact: <sip:juliet@balcony.thecappulets.example.com>
Content-Type: application/cpim-pidf+xml
Content-Length: ...
<?xml version="1.0" encoding="UTF-8"?>
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<presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
entity="pres:juliet@thecapulets.example.com">
<tuple id="balcony">
<status>
<basic>open</basic>
</status>
<timestamp>1597-02-14T01:00:00Z</timestamp>
</tuple>
</presence>
SIP Message 4:
SIP/2.0 200 OK
To: Romeo <pres:romeo@montague.example.net>;tag=23923
From: Juliet <pres:juliet@thecappulets.example.com>;tag=-938413
Call-ID: 98394813@orchard.montague.example.net
CSeq: 66734 NOTIFY
Contact: <sip:romeo@orchard.montague.example.net>
SIP Message 5 :
NOTIFY sip:romeo@orchard.montague.example.net SIP/2.0
To: Romeo <pres:romeo@montague.example.net>;tag=23923
From: Juliet <pres:juliet@thecappulets.example.com>;tag=-938413
Call-ID: 98394813@orchard.montague.example.net
CSeq: 66735 NOTIFY
Subscription-State: active;expires=3600
Contact: <sip:juliet@balcony.thecappulets.example.com>
Content-Type: application/cpim-pidf+xml
Content-Length: ...
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:cpim-pidf"
entity="pres:juliet@thecapulets.example.com">
<tuple id="balcony">
<status>
<basic>closed</basic>
</status>
<timestamp>1597-02-14T01:20:00Z</timestamp>
</tuple>
</presence>
SIP Message 6:
SIP/2.0 200 OK
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To: Romeo <pres:romeo@montague.example.net>;tag=23923
From: Juliet <pres:juliet@thecappulets.example.com>;tag=-938413
Call-ID: 98394813@orchard.montague.example.net
CSeq: 66735 NOTIFY
Contact: <sip:romeo@orchard.montague.example.net>
5. Security Considerations
This document introduces no additional security considerations as it
is merely a usage of two existing standards track protocols. UMPP
SIP Servers MUST implement TLS and the SIPS URI scheme. UMPP XMPP
Hosts MUST implement STARTTLS and SASL EXTERNAL). TLS
implementations used with UMPP (both SIP and XMPP) SHOULD implement
TLS mutual authentication.
6. Contributors
The ideas behind this document were the result of a collaborative
effort which initially involved Frank Cardello (Jabber), Jonathan
Christiansen (FaceTime), Lisa Dusseault (Xythos), Joe Hildebrand
(Jabber), Cullen Jennings (Cisco), Rohan Mahy (Cisco), Jon Peterson
(Neustar), and Jonathan Rosenberg (dynamicsoft) during a face-to-face
meeting in October 15, 2003 in San Jose, California. While this
group was unable to come to a consensus on the details of such a
profile during numerous meetings before and during IETF 58 in
Minneapolis, the editor feels that this concept was of significant
interest to the community and therefore should be published to invoke
wider discussion.
The use of sessions of XMPP setup via SIP was first documented by Ben
Campbell and Robert Sparks of dynamicsoft. This document borrows
heavily from their efforts.
7. Acknowledgments
The editor would also like to thank the following for participating
in additional discussions about this document and providing advice or
encouragement: Derek Atkins, Mark Day, Gonzalo Camarillo, Patrik
Faltstrom, Pat Galvin, Ted Hardie, Avshalom Houri, Pete Resnick,
Marshall Rose, and Peter St-Andre.
Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
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[2] Miller, J. and P. Saint-Andre, "XMPP Core",
draft-ietf-xmpp-core-13 (work in progress), June 2003.
[3] Miller, J. and P. Saint-Andre, "XMPP Instant Messaging",
draft-ietf-xmpp-im-12 (work in progress), June 2003.
[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.
[5] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol
(SIP): Locating SIP Servers", RFC 3263, June 2002.
[6] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002.
[7] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
[8] Rosenberg, J., "A Presence Event Package for the Session
Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work
in progress), January 2003.
[9] Fujimoto, S. and H. Sugano, "Presence Information Data Format
(PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May
2003.
[10] Peterson, J., "Common Profile for Instant Messaging (CPIM)",
draft-ietf-impp-im-03 (work in progress), May 2003.
[11] Peterson, J., "Common Profile for Presence (CPP)",
draft-ietf-impp-pres-03 (work in progress), May 2003.
Informational References
[12] Saint-Andre, P., "End-to-End Object Encryption in XMPP",
draft-ietf-xmpp-e2e-03 (work in progress), May 2003.
[13] Peterson, J., "Address Resolution for Instant Messaging and
Presence", draft-ietf-impp-srv-03 (work in progress), May 2003.
[14] Mahy, R., "Benefits of Session-Mode Instant Messaging",
draft-mahy-simple-why-session-mode-00.txt (work in progress),
January 2004.
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Author's Address
Rohan Mahy (editor)
Cisco Systems
EMail: rohan@cisco.com
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Intellectual Property Statement
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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