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2 Network Working Group P. Saint-Andre
3 Internet-Draft &yet
4 Intended status: Standards Track A. Houri
5 Expires: August 6, 2015 IBM
6 J. Hildebrand
7 Cisco Systems, Inc.
8 February 2, 2015
10 Interworking between the Session Initiation Protocol (SIP) and the
11 Extensible Messaging and Presence Protocol (XMPP): Instant Messaging
12 draft-ietf-stox-im-11
14 Abstract
16 This document defines a bidirectional protocol mapping for the
17 exchange of single instant messages between the Session Initiation
18 Protocol (SIP) and the Extensible Messaging and Presence Protocol
19 (XMPP).
21 Status of This Memo
23 This Internet-Draft is submitted in full conformance with the
24 provisions of BCP 78 and BCP 79.
26 Internet-Drafts are working documents of the Internet Engineering
27 Task Force (IETF). Note that other groups may also distribute
28 working documents as Internet-Drafts. The list of current Internet-
29 Drafts is at http://datatracker.ietf.org/drafts/current/.
31 Internet-Drafts are draft documents valid for a maximum of six months
32 and may be updated, replaced, or obsoleted by other documents at any
33 time. It is inappropriate to use Internet-Drafts as reference
34 material or to cite them other than as "work in progress."
36 This Internet-Draft will expire on August 6, 2015.
38 Copyright Notice
40 Copyright (c) 2015 IETF Trust and the persons identified as the
41 document authors. All rights reserved.
43 This document is subject to BCP 78 and the IETF Trust's Legal
44 Provisions Relating to IETF Documents
45 (http://trustee.ietf.org/license-info) in effect on the date of
46 publication of this document. Please review these documents
47 carefully, as they describe your rights and restrictions with respect
48 to this document. Code Components extracted from this document must
49 include Simplified BSD License text as described in Section 4.e of
50 the Trust Legal Provisions and are provided without warranty as
51 described in the Simplified BSD License.
53 Table of Contents
55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
56 2. Intended Audience . . . . . . . . . . . . . . . . . . . . . . 3
57 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
58 4. XMPP to SIP . . . . . . . . . . . . . . . . . . . . . . . . . 4
59 5. SIP to XMPP . . . . . . . . . . . . . . . . . . . . . . . . . 6
60 6. Content Types . . . . . . . . . . . . . . . . . . . . . . . . 8
61 7. Internationalization Considerations . . . . . . . . . . . . . 8
62 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
63 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
64 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
65 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
68 1. Introduction
70 In order to help ensure interworking between instant messaging (IM)
71 systems that conform to the instant messaging / presence requirements
72 [RFC2779], it is important to clearly define protocol mappings
73 between such systems. Within the IETF, work has proceeded on two
74 instant messaging technologies:
76 o Various extensions to the Session Initiation Protocol ([RFC3261])
77 for instant messaging, in particular the MESSAGE method extension
78 [RFC3428].
80 o The Extensible Messaging and Presence Protocol (XMPP), which
81 consists of a formalization of the core XML streaming protocols
82 developed originally by the Jabber open-source community; the
83 relevant specifications are [RFC6120] for the XML streaming layer
84 and [RFC6121] for basic presence and instant messaging extensions.
86 One approach to helping ensure interworking between these protocols
87 is to map each protocol to the abstract semantics described in
88 [RFC3860]; that is the approach taken by
89 [I-D.ietf-simple-cpim-mapping] and [RFC3922]. By contrast, the
90 approach taken in this document is to directly map semantics from one
91 protocol to another (i.e., from SIP/SIMPLE to XMPP and vice-versa),
92 since that is how existing systems solve the interworking problem.
94 Both XMPP and IM-capable SIP systems enable entities to exchange
95 "instant messages". The term "instant message" usually refers to a
96 message sent between two entities for delivery in close to real time
97 (rather than a message that is stored and forwarded to the intended
98 recipient upon request). This document covers single messages only
99 (sometimes called "pager-mode" messaging), since they form the lowest
100 common denominator for IM. Separate documents cover one-to-one chat
101 sessions [I-D.ietf-stox-chat] and multi-party groupchat
102 [I-D.ietf-stox-groupchat].
104 The architectural assumptions underlying such direct mappings are
105 provided in [RFC7247], including mapping of addresses and error
106 conditions. The mappings specified in this document cover basic
107 instant messaging functionality, i.e., the exchange of a single
108 instant message between a SIP user and an XMPP user in either
109 direction. Mapping of more advanced functionality is out of scope
110 for this document, but other documents in this "series" cover such
111 topics.
113 2. Intended Audience
115 The documents in this series are intended for use by software
116 developers who have an existing system based on one of these
117 technologies (e.g., SIP), and would like to enable communication from
118 that existing system to systems based on the other technology (e.g.,
119 XMPP). We assume that readers are familiar with the core
120 specifications for both SIP [RFC3261] and XMPP [RFC6120], with the
121 base document for this series [RFC7247], and with the following IM-
122 related specifications:
124 o Session Initiation Protocol (SIP) Extension for Instant Messaging
125 [RFC3428]
127 o Extensible Messaging and Presence Protocol: Instant Messaging and
128 Presence [RFC6121]
130 Note well that not all protocol-compliant messages are shown (such as
131 SIP 100 TRYING messages), in order to focus the reader on the
132 essential aspects of the protocol flows.
134 3. Terminology
136 A number of terms used here are explained in [RFC3261], [RFC3428],
137 [RFC6120], and [RFC6121].
139 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
140 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
141 "OPTIONAL" in this document are to be interpreted as described in
142 [RFC2119].
144 4. XMPP to SIP
146 As described in [RFC6121], a single instant message is an XML
147 stanza of type "normal" sent over an XML stream (since
148 "normal" is the default for the 'type' attribute of the
149 stanza, the attribute is often omitted).
151 When the XMPP user Juliet wants to send an
152 instant message to Romeo, she interacts with her XMPP client, which
153 generates an XMPP stanza. The syntax of the
154 stanza, including required and optional elements and attributes, is
155 defined in [RFC6121] (for single instant messages, the value of the
156 'to' address SHOULD be a "bare JID" of the form
157 "localpart@domainpart", as per [RFC6121]). The following is an
158 example of such a stanza:
160 Example 1: XMPP user sends message
162 |
164 | Art thou not Romeo, and a Montague?
165 |
167 Upon receiving such a message stanza, the XMPP server needs to
168 determine the identity of the domainpart in the 'to' address, which
169 it does by following the procedures explained in Section 5 of
170 [RFC7247]. If the domain is a SIP domain, the XMPP server will hand
171 off the message stanza to an XMPP-to-SIP gateway that natively
172 communicates with IM-aware SIP servers.
174 The XMPP-to-SIP gateway is then responsible for translating the XMPP
175 message stanza into a SIP MESSAGE request from the XMPP user to the
176 SIP user:
178 Example 2: XMPP user sends message (SIP transformation)
180 | MESSAGE sip:romeo@example.net SIP/2.0
181 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse
182 | Max-Forwards: 70
183 | To: sip:romeo@example.net
184 | From: ;tag=12345
185 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA
186 | CSeq: 1 MESSAGE
187 | Content-Type: text/plain
188 | Content-Length: 35
189 |
190 | Art thou not Romeo, and a Montague?
191 The destination SIP server is responsible for delivering the message
192 to the intended recipient, and the recipient is responsible for
193 generating a response (e.g., 200 OK).
195 Example 3: SIP user agent indicates receipt of message
197 | SIP/2.0 200 OK
198 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse
199 | From: sip:romeo@example.net;tag=vwxyz
200 | To: sip:juliet@example.com;tag=12345
201 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA
202 | CSeq: 1 MESSAGE
203 | Content-Length: 0
205 As described in [RFC3428], a downstream proxy could fork a MESSAGE
206 request, but it would return only one 200 OK to the gateway.
208 Note: This document does not specify handling of the 200 OK by the
209 XMPP-to-SIP gateway (e.g., to enable message acknowledgements).
210 See [I-D.ietf-stox-chat] for a mapping of message acknowledgements
211 in the context of one-to-one chat sessions.
213 The mapping of XMPP syntax to SIP syntax MUST be as shown in the
214 following table. (Mappings for several aspects not mentioned here
215 are specified in [I-D.ietf-stox-chat].)
217 Table 1: Message syntax mapping from XMPP to SIP
219 +-----------------------------+--------------------------+
220 | XMPP Element or Attribute | SIP Header or Contents |
221 +-----------------------------+--------------------------+
222 | | body of MESSAGE |
223 | | Subject |
224 | | Call-ID |
225 | from | From (1) |
226 | id | (no mapping) |
227 | to | To or Request-URI |
228 | type | (no mapping) (2) |
229 | xml:lang | Content-Language |
230 +-----------------------------+--------------------------+
232 1. As shown in the foregoing example and described in [RFC7247], the
233 XMPP-to-SIP gateway MUST map the bare JID
234 ("localpart@domainpart") of the XMPP sender to the SIP From
235 header and include the resourcepart of the full JID as the GRUU
236 portion [RFC5627] of the SIP URI.
238 2. Because there is no SIP header field that matches the meaning of
239 the XMPP message 'type' values ("normal", "chat", "groupchat",
240 "headline", "error"), no general mapping is possible here.
242 5. SIP to XMPP
244 As described in [RFC3428], a single instant message is a SIP MESSAGE
245 request sent from a SIP user agent to an intended recipient who is
246 most generally referenced by an Instant Message URI of the form
247 but who might be referenced by a SIP or SIPS URI of
248 the form or .
250 When the SIP user Romeo wants to send an
251 instant message to Juliet, he interacts with his SIP user agent,
252 which generates a SIP MESSAGE request. The syntax of the MESSAGE
253 request is defined in [RFC3428]. The following is an example of such
254 a request:
256 Example 4: SIP user sends message
258 | MESSAGE sip:juliet@example.com SIP/2.0
259 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677
260 | Max-Forwards: 70
261 | To: sip:juliet@example.com
262 | From: sip:romeo@example.net;tag=vwxyz
263 | Call-ID: 9E97FB43-85F4-4A00-8751-1124FD4C7B2E
264 | CSeq: 1 MESSAGE
265 | Content-Type: text/plain
266 | Content-Length: 44
267 |
268 | Neither, fair saint, if either thee dislike.
270 Section 5 of [RFC3428] stipulates that a SIP User Agent presented
271 with an im: URI should resolve it to a sip: or sips: URI. Therefore
272 we assume that the Request-URI of a request received by an IM-capable
273 SIP-to-XMPP gateway will contain a sip: or sips: URI. Upon receiving
274 the MESSAGE, the SIP server needs to determine the identity of the
275 domain portion of the Request-URI or To header, which it does by
276 following the procedures explained in Section 5 of [RFC7247]. If the
277 domain is an XMPP domain, the SIP server will hand off the MESSAGE to
278 an associated SIP-to-XMPP gateway that natively communicates with
279 XMPP servers.
281 The SIP-to-XMPP gateway is then responsible for translating the
282 request into an XMPP message stanza from the SIP user to the XMPP
283 user and returning a SIP "200 OK" message to the sender:
285 Example 5: SIP user sends message (XMPP transformation)
287 |
289 | Neither, fair saint, if either thee dislike.
290 |
292 Note that the stanza handling rules specified in [RFC6121] allow the
293 receiving XMPP server to deliver a message stanza whose 'to' address
294 is a bare JID ("localpart@domainpart") to multiple connected devices.
295 This is similar to the "forking" of messages in SIP.
297 The mapping of SIP syntax to XMPP syntax MUST be as shown in the
298 following table. (Mappings for several aspects not mentioned here
299 are specified in [I-D.ietf-stox-chat].)
301 Table 2: Message syntax mapping from SIP to XMPP
303 +--------------------------+-----------------------------+
304 | SIP Header or Contents | XMPP Element or Attribute |
305 +--------------------------+-----------------------------+
306 | Call-ID | |
307 | Content-Language | xml:lang |
308 | CSeq | (no mapping) |
309 | From | from (1) |
310 | Subject | |
311 | Request-URI or To | to |
312 | body of MESSAGE | |
313 +--------------------------+-----------------------------+
315 1. As shown in the foregoing example and described in [RFC7247], if
316 the IM-capable SIP-to-XMPP gateway has information about the GRUU
317 [RFC5627] of the particular endpoint that sent the SIP message
318 then it MUST map the sender's address to a full JID
319 ("localpart@domainpart/resourcepart") in the 'from' attribute of
320 the XMPP stanza and include the GRUU as the resourcepart.
322 When transforming SIP pager-mode messages, an IM-capable SIP-to-XMPP
323 gateway MUST specify no XMPP 'type' attribute or, equivalently, a
324 'type' attribute whose value is "normal" [RFC6121].
326 See Section 6 of this document about the handling of SIP message
327 bodies that contain content types other than plain text.
329 6. Content Types
331 SIP requests of type MESSAGE are allowed to contain essentially any
332 content type. The recommended procedures for SIP-to-XMPP gateways to
333 use in handling these content types are as follows.
335 An IM-aware SIP-to-XMPP gateway MUST process SIP messages that
336 contain message bodies of type "text/plain" and MUST encapsulate such
337 message bodies as the XML character data of the XMPP element.
339 An IM-aware SIP-to-XMPP gateway SHOULD process SIP messages that
340 contain message bodies of type "text/html"; if so, a gateway MUST
341 transform the "text/html" content into XHTML content that conforms to
342 the XHTML-IM Integration Set specified in [XEP-0071].
344 Although an IM-aware SIP-to-XMPP gateway MAY process SIP messages
345 that contain message bodies of types other than "text/plain" and
346 "text/html", the handling of such content types is a matter of
347 implementation.
349 7. Internationalization Considerations
351 Both XMPP and SIP support the UTF-8 encoding [RFC3629] of Unicode
352 characters [UNICODE] within messages, and signalling of the language
353 for a particular message (in XMPP via the 'xml:lang' attribute and in
354 SIP via the Content-Language header). Several examples follow, using
355 the "XML Notation" [RFC3987] for Unicode characters outside the ASCII
356 range.
358 Example 6: SIP user sends message
360 | MESSAGE sip:juliet@example.com SIP/2.0
361 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677
362 | Max-Forwards: 70
363 | To: sip:juliet@example.com
364 | From: sip:romeo@example.net;tag=vwxyz
365 | Call-ID: 9E97FB43-85F4-4A00-8751-1124FD4C7B2E
366 | CSeq: 1 MESSAGE
367 | Content-Type: text/plain
368 | Content-Length: 45
369 | Content-Language: cs
370 |
371 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡,
372 | nenavid쎭얡-li jedno nebo druh쎩.
374 Example 7: SIP user sends message (XMPP transformation)
376 |
379 |
380 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡,
381 | nenavid쎭얡-li jedno nebo druh쎩.
382 |
383 |
385 8. IANA Considerations
387 This document requests no actions of IANA.
389 9. Security Considerations
391 Detailed security considerations for instant messaging protocols are
392 given in [RFC2779], for SIP-based instant messaging in [RFC3428] (see
393 also [RFC3261]), and for XMPP-based instant messaging in [RFC6121]
394 (see also [RFC6120]). The security considerations provided in
395 [RFC7247] also apply.
397 This document specifies methods for exchanging instant messages
398 through a gateway that translates between SIP and XMPP. Such a
399 gateway MUST be compliant with the minimum security requirements of
400 the instant messaging protocols for which it translates (i.e., SIP
401 and XMPP). The addition of gateways to the security model of instant
402 messaging specified in [RFC2779] introduces some new risks. In
403 particular, end-to-end security properties (especially
404 confidentiality and integrity) between instant messaging user agents
405 that interface through an IM-capable SIP-to-XMPP gateway can be
406 provided only if common formats are supported. Specification of
407 those common formats is out of scope for this document, although it
408 is preferred to use [RFC3862] for instant messages.
410 10. References
412 10.1. Normative References
414 [I-D.ietf-stox-chat]
415 Saint-Andre, P. and S. Loreto, "Interworking between the
416 Session Initiation Protocol (SIP) and the Extensible
417 Messaging and Presence Protocol (XMPP): One-to-One Text
418 Chat Sessions", draft-ietf-stox-chat-08 (work in
419 progress), August 2014.
421 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
422 Requirement Levels", BCP 14, RFC 2119, March 1997.
424 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
425 A., Peterson, J., Sparks, R., Handley, M., and E.
426 Schooler, "SIP: Session Initiation Protocol", RFC 3261,
427 June 2002.
429 [RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
430 and D. Gurle, "Session Initiation Protocol (SIP) Extension
431 for Instant Messaging", RFC 3428, December 2002.
433 [RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User
434 Agent URIs (GRUUs) in the Session Initiation Protocol
435 (SIP)", RFC 5627, October 2009.
437 [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
438 Protocol (XMPP): Core", RFC 6120, March 2011.
440 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence
441 Protocol (XMPP): Instant Messaging and Presence", RFC
442 6121, March 2011.
444 [RFC7247] Saint-Andre, P., Houri, A., and J. Hildebrand,
445 "Interworking between the Session Initiation Protocol
446 (SIP) and the Extensible Messaging and Presence Protocol
447 (XMPP): Architecture, Addresses, and Error Handling", RFC
448 7247, May 2014.
450 [XEP-0071]
451 Saint-Andre, P., "XHTML-IM", XSF XEP 0071, November 2012.
453 10.2. Informative References
455 [I-D.ietf-simple-cpim-mapping]
456 Rosenberg, J. and B. Campbell, "CPIM Mapping of SIMPLE
457 Presence and Instant Messaging", draft-ietf-simple-cpim-
458 mapping-01 (work in progress), June 2002.
460 [I-D.ietf-stox-groupchat]
461 Saint-Andre, P., Corretge, S., and S. Loreto,
462 "Interworking between the Session Initiation Protocol
463 (SIP) and the Extensible Messaging and Presence Protocol
464 (XMPP): Groupchat", draft-ietf-stox-groupchat-08 (work in
465 progress), November 2014.
467 [RFC2779] Day, M., Aggarwal, S., and J. Vincent, "Instant Messaging
468 / Presence Protocol Requirements", RFC 2779, February
469 2000.
471 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
472 10646", STD 63, RFC 3629, November 2003.
474 [RFC3860] Peterson, J., "Common Profile for Instant Messaging
475 (CPIM)", RFC 3860, August 2004.
477 [RFC3862] Klyne, G. and D. Atkins, "Common Presence and Instant
478 Messaging (CPIM): Message Format", RFC 3862, August 2004.
480 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and
481 Presence Protocol (XMPP) to Common Presence and Instant
482 Messaging (CPIM)", RFC 3922, October 2004.
484 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
485 Identifiers (IRIs)", RFC 3987, January 2005.
487 [UNICODE] The Unicode Consortium, "The Unicode Standard, Version
488 6.3", 2013,
489 .
491 Appendix A. Acknowledgements
493 The authors wish to thank the following individuals for their
494 feedback: Mary Barnes, Dave Cridland, Dave Crocker, Adrian Georgescu,
495 Christer Holmberg, Saul Ibarra Corretge, Olle Johansson, Paul
496 Kyzivat, Salvatore Loreto, Daniel-Constantin Mierla, and Tory Patnoe.
498 The authors gratefully acknowledge the assistance of Markus Isomaki
499 and Yana Stamcheva as the working group chairs and Gonzalo Camarillo
500 and Alissa Cooper as the sponsoring Area Directors.
502 Peter Saint-Andre wishes to acknowledge Cisco Systems, Inc., for
503 employing him during his work on earlier versions of this document.
505 Authors' Addresses
507 Peter Saint-Andre
508 &yet
510 Email: peter@andyet.com
511 URI: https://andyet.com/
512 Avshalom Houri
513 IBM
514 Rorberg Building, Pekris 3
515 Rehovot 76123
516 Israel
518 Email: avshalom@il.ibm.com
520 Joe Hildebrand
521 Cisco Systems, Inc.
522 1899 Wynkoop Street, Suite 600
523 Denver, CO 80202
524 USA
526 Email: jhildebr@cisco.com