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. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 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. Mahy Expires July 27, 2004 [Page 1] Internet-Draft Unified IM & P Proposal January 2004 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 Mahy Expires July 27, 2004 [Page 2] Internet-Draft Unified IM & P Proposal January 2004 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. Mahy Expires July 27, 2004 [Page 3] Internet-Draft Unified IM & P Proposal January 2004 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), Mahy Expires July 27, 2004 [Page 4] Internet-Draft Unified IM & P Proposal January 2004 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 From: Romeo ;tag=29923923 Call-ID: 2349098234@orchard.montague.example.net CSeq: 13992 INVITE Contact: 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 Mahy Expires July 27, 2004 [Page 5] Internet-Draft Unified IM & P Proposal January 2004 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 ;tag=939231235 From: Romeo ;tag=29923923 Call-ID: 2349098234@orchard.montague.example.net CSeq: 13992 INVITE Contact: 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 ;tag=939231235 From: Romeo ;tag=29923923 Call-ID: 2349098234@orchard.montague.example.net CSeq: 13992 ACK XMPP Stanza 1: Art thou not Romeo, and a Montague? 283461923759234 XMPP Stanza 2: Mahy Expires July 27, 2004 [Page 6] Internet-Draft Unified IM & P Proposal January 2004 Neither, fair saint, if either thee dislike. 283461923759234 XMPP Stanza 3: How cam'st thou hither, tell me, and wherefore? 283461923759234 SIP Message 4: BYE sip:romeo@orchard.montague.example.net SIP/2.0 From: Juliet ;tag=939231235 To: Romeo ;tag=29923923 Call-ID: 2349098234@orchard.montague.example.net CSeq: 33903 BYE SIP Message 5: SIP/2.0 200 OK From: Juliet ;tag=9392312353 To: Romeo ;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) Mahy Expires July 27, 2004 [Page 7] Internet-Draft Unified IM & P Proposal January 2004 | | |----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 From: Romeo ;tag=23923 Call-ID: 98394813@orchard.montague.example.net CSeq: 13667 SUBSCRIBE Event: presence Expires: 3600 Contact: SIP Message 2 : SIP/2.0 200 OK To: Juliet ;tag=-938413 From: Romeo ;tag=23923 Call-ID: 98394813@orchard.montague.example.net CSeq: 13667 SUBSCRIBE Subscription-State: active;expires=3600 Contact: SIP Message 3 : NOTIFY sip:romeo@orchard.montague.example.net SIP/2.0 To: Romeo ;tag=23923 From: Juliet ;tag=-938413 Call-ID: 98394813@orchard.montague.example.net CSeq: 66734 NOTIFY Subscription-State: active;expires=3600 Contact: Content-Type: application/cpim-pidf+xml Content-Length: ... Mahy Expires July 27, 2004 [Page 8] Internet-Draft Unified IM & P Proposal January 2004 open 1597-02-14T01:00:00Z SIP Message 4: SIP/2.0 200 OK To: Romeo ;tag=23923 From: Juliet ;tag=-938413 Call-ID: 98394813@orchard.montague.example.net CSeq: 66734 NOTIFY Contact: SIP Message 5 : NOTIFY sip:romeo@orchard.montague.example.net SIP/2.0 To: Romeo ;tag=23923 From: Juliet ;tag=-938413 Call-ID: 98394813@orchard.montague.example.net CSeq: 66735 NOTIFY Subscription-State: active;expires=3600 Contact: Content-Type: application/cpim-pidf+xml Content-Length: ... closed 1597-02-14T01:20:00Z SIP Message 6: SIP/2.0 200 OK Mahy Expires July 27, 2004 [Page 9] Internet-Draft Unified IM & P Proposal January 2004 To: Romeo ;tag=23923 From: Juliet ;tag=-938413 Call-ID: 98394813@orchard.montague.example.net CSeq: 66735 NOTIFY Contact: 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. Mahy Expires July 27, 2004 [Page 10] Internet-Draft Unified IM & P Proposal January 2004 [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. Mahy Expires July 27, 2004 [Page 11] Internet-Draft Unified IM & P Proposal January 2004 Author's Address Rohan Mahy (editor) Cisco Systems EMail: rohan@cisco.com Mahy Expires July 27, 2004 [Page 12] Internet-Draft Unified IM & P Proposal January 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION Mahy Expires July 27, 2004 [Page 13] Internet-Draft Unified IM & P Proposal January 2004 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Mahy Expires July 27, 2004 [Page 14]