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2 Network Working Group P. Saint-Andre
3 Internet-Draft Cisco Systems, Inc.
4 Intended status: Standards Track A. Houri
5 Expires: March 10, 2014 IBM
6 J. Hildebrand
7 Cisco Systems, Inc.
8 September 6, 2013
10 Interworking between the Session Initiation Protocol (SIP) and the
11 Extensible Messaging and Presence Protocol (XMPP): Instant Messaging
12 draft-ietf-stox-im-03
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 March 10, 2014.
38 Copyright Notice
40 Copyright (c) 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
56 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
57 3. XMPP to SIP . . . . . . . . . . . . . . . . . . . . . . . . . 4
58 4. SIP to XMPP . . . . . . . . . . . . . . . . . . . . . . . . . 6
59 5. Content Types . . . . . . . . . . . . . . . . . . . . . . . . 7
60 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
61 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
62 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
63 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
64 8.2. Informative References . . . . . . . . . . . . . . . . . . 9
65 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 10
66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
68 1. Introduction
70 In order to help ensure interworking between instant messaging
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, as developed within the SIP for Instant
78 Messaging and Presence Leveraging Extensions (SIMPLE) Working
79 Group; the relevant specification for instant messaging is
80 [RFC3428]
81 o The Extensible Messaging and Presence Protocol (XMPP), which
82 consists of a formalization of the core XML streaming protocols
83 developed originally by the Jabber open-source community; the
84 relevant specifications are [RFC6120] for the XML streaming layer
85 and [RFC6121] for basic presence and instant messaging extensions
87 One approach to helping ensure interworking between these protocols
88 is to map each protocol to the abstract semantics described in
89 [RFC3860]; that is the approach taken by
90 [I-D.ietf-simple-cpim-mapping] and [RFC3922]. By contrast, the
91 approach taken in this document is to directly map semantics from one
92 protocol to another (i.e., from SIP/SIMPLE to XMPP and vice-versa).
94 Both XMPP and IM-aware SIP systems enable entities to exchange
95 "instant messages". The term "instant message" usually refers to
96 messages sent between two entities for delivery in close to real time
97 (rather than messages that are 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 instant messaging. One-to-one chat sessions
101 and multi-party groupchat are covered in separate documents.
103 The architectural assumptions underlying such direct mappings are
104 provided in [I-D.ietf-stox-core], including mapping of addresses and
105 error condisions. The mappings specified in this document cover
106 basic instant messaging functionality, i.e., the exchange of a single
107 instant message between a SIP user and an XMPP user in either
108 direction. Mapping of more advanced functionality is out of scope
109 for this document, but other documents in this "series" cover such
110 topics.
112 The discussion venue for this document is the mailing list of the
113 STOX WG; visit https://www.ietf.org/mailman/listinfo/stox for
114 subscription information and discussion archives.
116 2. Terminology
118 A number of terms used here are explained in [RFC3261], [RFC3428],
119 [RFC6120], and [RFC6121].
121 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
122 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
123 "OPTIONAL" in this document are to be interpreted as described in
124 [RFC2119].
126 3. XMPP to SIP
128 As described in [RFC6121], a single instant message is an XML
129 stanza of type "normal" sent over an XML stream (since
130 "normal" is the default for the 'type' attribute of the
131 stanza, the attribute is often omitted). In this document we will
132 assume that such a message is sent from an XMPP client to an XMPP
133 server over an XML stream negotiated between the client and the
134 server, and that the client is controlled by a human user (this is a
135 simplifying assumption introduced for explanatory purposes only; the
136 XMPP sender could be a bot-controlled client, a component such as a
137 workflow application, a server, etc.). Continuing the tradition of
138 Shakespearean examples in XMPP documentation, we will say that the
139 XMPP user has an XMPP address of .
141 When Juliet wants to send an instant message to Romeo, she interacts
142 with her XMPP client, which generates an XMPP stanza. The
143 syntax of the stanza, including required and optional
144 elements and attributes, is defined in [RFC6121] (for single instant
145 messages, the value of the 'to' address SHOULD be a "bare JID" of the
146 form "localpart@domainpart/resourcepart"). The following is an
147 example of such a stanza:
149 Example: XMPP user sends message:
151 |
153 | Art thou not Romeo, and a Montague?
154 |
156 Upon receiving such a stanza, the XMPP server to which Juliet has
157 connected needs to determine the identity of the foreign domain,
158 which it does by following the procedures discussed in
159 [I-D.ietf-stox-core]. Here we assume that the XMPP server has
160 determined the foreign domain is serviced by a SIMPLE server, that it
161 contains or has available to it an XMPP-SIMPLE gateway or connection
162 manager (which enables it to speak natively to SIMPLE servers), and
163 that it hands off the message stanza to the XMPP-SIMPLE gateway.
165 The XMPP-SIMPLE gateway is then responsible for translating the XMPP
166 message stanza into a SIP MESSAGE request from the XMPP user to the
167 SIP user:
169 Example: XMPP user sends message (SIP transformation):
171 | MESSAGE sip:romeo@example.net SIP/2.0
172 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse
173 | Max-Forwards: 70
174 | To: sip:romeo@example.net
175 | From: ;tag=12345
176 | Call-ID: Hr0zny9l3@example.com
177 | CSeq: 1 MESSAGE
178 | Content-Type: text/plain
179 | Content-Length: 35
180 |
181 | Art thou not Romeo, and a Montague?
183 The mapping of XMPP syntax elements to SIP syntax elements SHOULD be
184 as shown in the following table. (Mappings for elements not
185 mentioned are undefined.)
187 Table 1: Message syntax mapping from XMPP to SIP
189 +-----------------------------+--------------------------+
190 | XMPP Element or Attribute | SIP Header or Contents |
191 +-----------------------------+--------------------------+
192 | | body of MESSAGE |
193 | | Subject |
194 | | Call-ID |
195 | from | From (1) |
196 | id | (no mapping) |
197 | to | To |
198 | type | (no mapping) |
199 | xml:lang | Content-Language |
200 +-----------------------------+--------------------------+
202 1. As shown in the foregoing example and described in
203 [I-D.ietf-stox-core], the XMPP-SIMPLE gateway SHOULD map the full
204 JID (localpart@domainpart/resourcepart) of the XMPP sender to the
205 SIP From header and include the resourcepart to the GRUU portion
206 of the SIP URI [RFC5627].
208 4. SIP to XMPP
210 As described in [RFC3428], a single instant message is a SIP MESSAGE
211 request sent from a SIP user agent to an intended recipient who is
212 most generally referenced by an Instant Message URI of the form
213 but who might be referenced by a SIP or SIPS URI of
214 the form or . Here again we
215 introduce the simplifying assumption that the user agent is
216 controlled by a human user, whom we shall dub .
218 When Romeo wants to send an instant message to Juliet, he interacts
219 with his SIP user agent, which generates a SIP MESSAGE request. The
220 syntax of the MESSAGE request is defined in [RFC3428]. The following
221 is an example of such a request:
223 Example: SIP user sends message:
225 | MESSAGE sip:juliet@example.com SIP/2.0
226 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677
227 | Max-Forwards: 70
228 | To: sip:juliet@example.com
229 | From: sip:romeo@example.net
230 | Call-ID: M4spr4vdu@example.net
231 | CSeq: 1 MESSAGE
232 | Content-Type: text/plain
233 | Content-Length: 44
234 |
235 | Neither, fair saint, if either thee dislike.
237 Section 5 of [RFC3428] stipulates that a SIP User Agent presented
238 with an im: URI should resolve it to a sip: or sips: URI. Therefore
239 we assume that the Request-URI of a request received by a SIMPLE-XMPP
240 gateway will contain a sip: or sips: URI. The gateway SHOULD resolve
241 that address to an im: URI for SIP MESSAGE requests, then follow the
242 rules in [RFC3861] regarding the "_im" SRV service for the target
243 domain contained in the Request-URI. If SRV address resolution fails
244 for the "_im" service, the gateway MUST either attempt a lookup for
245 the "_xmpp-server" service as specified in [RFC6120] or return an
246 error to the sender (the SIP "502 Bad Gateway" error seems most
247 appropriate; see [I-D.ietf-stox-core] for details). If SRV address
248 resolution succeeds, the gateway is responsible for translating the
249 request into an XMPP message stanza from the SIP user to the XMPP
250 user and returning a SIP "200 OK" message to the sender:
252 Example: SIP user sends message (XMPP transformation):
254 |
256 | Neither, fair saint, if either thee dislike.
257 |
259 The mapping of SIP syntax elements to XMPP syntax elements SHOULD be
260 as shown in the following table. (Mappings for elements not
261 mentioned in the foregoing table are undefined.)
263 Table 2: Message syntax mapping from SIP to XMPP
265 +--------------------------+-----------------------------+
266 | SIP Header or Contents | XMPP Element or Attribute |
267 +--------------------------+-----------------------------+
268 | Call-ID | |
269 | Content-Language | xml:lang |
270 | CSeq | (no mapping) |
271 | From | from (1) |
272 | Subject | |
273 | Request-URI | to |
274 | body of MESSAGE | |
275 +--------------------------+-----------------------------+
277 1. As shown in the foregoing example and described in
278 [I-D.ietf-stox-core], if the SIMPLE-XMPP gateway has information
279 about the GRUU [RFC5627] of the particular endpoint that sent the
280 SIP message then it SHOULD map the sender's address to a full JID
281 (localpart@domainpart/resourcepart) in the 'from' attribute of
282 the XMPP stanza and include the GRUU as the resourcepart.
284 When transforming SIP pager-mode messages, a SIMPLE-XMPP gateway
285 SHOULD specify no XMPP 'type' attribute or, equivalently, a 'type'
286 attribute whose value is "normal" [RFC6121].
288 See Section 5 of this document about the handling of SIP message
289 bodies that contain content types other than plain text.
291 5. Content Types
293 SIP requests of type MESSAGE are allowed to contain essentially any
294 content type. The recommended procedures for SIMPLE-to-XMPP gateways
295 to use in handling these content types are as follows.
297 A SIMPLE-to-XMPP gateway MUST process SIP messages that contain
298 message bodies of type "text/plain" and MUST encapsulate such message
299 bodies as the XML character data of the XMPP element.
301 A SIMPLE-to-XMPP gateway SHOULD process SIP messages that contain
302 message bodies of type "text/html"; if so, a gateway MUST transform
303 the "text/html" content into XHTML content that conforms to the XHTML
304 1.0 Integration Set specified in [XEP-0071].
306 Although a SIMPLE-to-XMPP gateway MAY process SIP messages that
307 contain message bodies of types other than "text/plain" and "text/
308 html", the handling of such content types is a matter of
309 implementation.
311 6. Security Considerations
313 Detailed security considerations for instant messaging protocols are
314 given in [RFC2779], for SIP-based instant messaging in [RFC3428] (see
315 also [RFC3261]), and for XMPP-based instant messaging in [RFC6121]
316 (see also [RFC6120]).
318 This document specifies methods for exchanging instant messages
319 through a gateway that translates between SIP and XMPP. Such a
320 gateway MUST be compliant with the minimum security requirements of
321 the instant messaging protocols for which it translates (i.e., SIP
322 and XMPP). The addition of gateways to the security model of instant
323 messaging specified in [RFC2779] introduces some new risks. In
324 particular, end-to-end security properties (especially
325 confidentiality and integrity) between instant messaging user agents
326 that interface through a SIMPLE-XMPP gateway can be provided only if
327 common formats are supported. Specification of those common formats
328 is out of scope for this document, although it is preferred to use
329 [RFC3862] for instant messages.
331 7. IANA Considerations
333 This document requests no actions of IANA.
335 8. References
337 8.1. Normative References
339 [I-D.ietf-stox-core]
340 Saint-Andre, P., Houri, A., and J. Hildebrand,
341 "Interworking between the Session Initiation Protocol
342 (SIP) and the Extensible Messaging and Presence Protocol
343 (XMPP): Core", draft-ietf-stox-core-04 (work in progress),
344 September 2013.
346 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
347 Requirement Levels", BCP 14, RFC 2119, March 1997.
349 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
350 A., Peterson, J., Sparks, R., Handley, M., and E.
351 Schooler, "SIP: Session Initiation Protocol", RFC 3261,
352 June 2002.
354 [RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
355 and D. Gurle, "Session Initiation Protocol (SIP) Extension
356 for Instant Messaging", RFC 3428, December 2002.
358 [RFC3861] Peterson, J., "Address Resolution for Instant Messaging
359 and Presence", RFC 3861, August 2004.
361 [RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User
362 Agent URIs (GRUUs) in the Session Initiation Protocol
363 (SIP)", RFC 5627, October 2009.
365 [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
366 Protocol (XMPP): Core", RFC 6120, March 2011.
368 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence
369 Protocol (XMPP): Instant Messaging and Presence",
370 RFC 6121, March 2011.
372 [XEP-0071]
373 Saint-Andre, P., "XHTML-IM", XSF XEP 0071, November 2012.
375 8.2. Informative References
377 [I-D.ietf-simple-cpim-mapping]
378 Rosenberg, J. and B. Campbell, "CPIM Mapping of SIMPLE
379 Presence and Instant Messaging",
380 draft-ietf-simple-cpim-mapping-01 (work in progress),
381 June 2002.
383 [RFC2779] Day, M., Aggarwal, S., and J. Vincent, "Instant Messaging
384 / Presence Protocol Requirements", RFC 2779,
385 February 2000.
387 [RFC3860] Peterson, J., "Common Profile for Instant Messaging
388 (CPIM)", RFC 3860, August 2004.
390 [RFC3862] Klyne, G. and D. Atkins, "Common Presence and Instant
391 Messaging (CPIM): Message Format", RFC 3862, August 2004.
393 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and
394 Presence Protocol (XMPP) to Common Presence and Instant
395 Messaging (CPIM)", RFC 3922, October 2004.
397 Appendix A. Acknowledgements
399 The authors wish to thank the following individuals for their
400 feedback: Adrian Georgescu, Christer Holmberg, Saul Ibarra Corretge,
401 Paul Kyzivat, Salvatore Loreto, and Tory Patnoe.
403 Authors' Addresses
405 Peter Saint-Andre
406 Cisco Systems, Inc.
407 1899 Wynkoop Street, Suite 600
408 Denver, CO 80202
409 USA
411 Phone: +1-303-308-3282
412 Email: psaintan@cisco.com
414 Avshalom Houri
415 IBM
416 Rorberg Building, Pekris 3
417 Rehovot 76123
418 Israel
420 Email: avshalom@il.ibm.com
422 Joe Hildebrand
423 Cisco Systems, Inc.
424 1899 Wynkoop Street, Suite 600
425 Denver, CO 80202
426 USA
428 Email: jhildebr@cisco.com