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Network Working Group S. Veikkolainen
Internet-Draft M. Isomaki
Intended status: Standards Track Nokia
Expires: January 11, 2010 July 10, 2009
Guidelines and Protocol Extensions for Combining SIP Based Real-time
Media Sessions With XMPP Based Instant Messaging and Presence Service.
draft-veikkolainen-sip-voip-xmpp-im-01
Status of this Memo
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Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Abstract
This memo defines guidelines and protocol extensions for combining
Session Initiation Protocol (SIP) based real-time media sessions with
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Extensible Messaging and Presence Protocol (XMPP) based instant
messaging and presence services in a seamless manner. This is
accomplished by integration and protocol extension support in the
endpoints, without requiring any changes in the SIP or XMPP server
infrastructure. It is even possible that SIP and XMPP services are
offered by different service providers.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
3. Deployment scenarios and use cases . . . . . . . . . . . . . . 4
3.1. Deployment scenarios . . . . . . . . . . . . . . . . . . . 4
3.2. Use cases . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Overview of operation . . . . . . . . . . . . . . . . . . . . 7
5.1. Endpoints engaged in XMPP conversation adding a SIP
session . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. Endpoints engaged in a SIP session adding an XMPP IM
conversation . . . . . . . . . . . . . . . . . . . . . . . 8
5.3. Using XMPP presence for publishing and obtaining SIP
contact address, media capabilities and availability . . . 9
6. Protocol extensions . . . . . . . . . . . . . . . . . . . . . 9
6.1. Extensions to XMPP message stanza . . . . . . . . . . . . 9
6.1.1. The <sip-contact> element . . . . . . . . . . . . . . 9
6.1.2. The <sip-correlation> element . . . . . . . . . . . . 10
6.2. Extensions to XMPP presence stanza . . . . . . . . . . . . 11
6.3. Extensions to SIP headers . . . . . . . . . . . . . . . . 11
6.3.1. SIP XMPP-Thread header . . . . . . . . . . . . . . . . 11
6.3.2. SIP XMPP-Contact header . . . . . . . . . . . . . . . 12
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Endpoint engaged in an IM session adds a voice/video
component to the conversation . . . . . . . . . . . . . . 14
7.2. Endpoint engaged in a SIP session adds an XMPP IM
conversation . . . . . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
Currently most standards-based Voice over IP (VoIP) deployments use
Session Initiation Protocol (SIP). In addition to providing basic
voice service SIP has an extensive support for more advanced
telephony features including interworking with the traditional Public
Switched Telephone Network (PSTN). SIP is also gaining popularity in
the field of video communication.
At the same time, the Extensible Messaging and Presence Protocol
(XMPP) is enjoying widespread usage in instant messaging and presence
services. An interesting scenario arises when a SIP based voice and
video service is combined together with an XMPP based instant
messaging and presence service.
This memo describes how SIP based real-time sessions and XMPP based
IM and presence can be offered using existing server implementations.
This memo also presents a set of requirements and protocol extensions
for SIP User Agent and XMPP client implementations in order to offer
a seamless usage experience when using SIP based VoIP with XMPP based
instant messaging and presence.
Combining SIP based real-time services with XMPP based presence and
IM service can be accomplished in the endpoints; no support is needed
in the service infrastructure. It is even possible to achieve
seamless integration when SIP and XMPP services are offered by
different service providers.
The main issues that need to be addressed when offering such combined
services are identities and addressing. SIP and XMPP both use a
similar addressing scheme (based on "user@domain" structure) to
identify users and endpoints but there are some subtle differences as
well. We do not assume any algorithmic correlation or translation
between SIP and XMPP Universal Resource Identifiers (URI), even when
they identify the same user or endpoint. New protocol mechanisms are
needed to tie together communication contexts that are based on the
two protocols.
We do not discuss how protocol translation through a gateway could be
performed between the protocols; this is the subject of other work,
see for example [I-D.saintandre-sip-xmpp-core].
We focus on one-to-one communication only. Multiparty use cases such
as combining SIP voice conference with XMPP IM group chat are beyond
the scope.
The document structure is as follows: Section 2 presents the document
conventions and definitions, Section 3 presents deployment scenarios
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and use cases, Section 4 lists the requirements, Section 5 provides
an overview of the protocol operation, Section 6 provides the
definitions, and examples are presented in Section 7.
2. Conventions Used in This Document
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 BCP 14, RFC 2119
[RFC2119] and indicate requirement levels for compliant
implementations.
The following definitions are used in this memo:
Integrated endpoint is an implementation that combines the
functionality of SIP User Agent and XMPP client and can offer its
user a seamless user experience in the sense that a single UI and
contact information can be user for voice and video communication
using the SIP protocol as well as instant messaging and presence
sharing using XMPP. We assume an integrated endpoint is able to
support SIP and XMPP protocol extensions defined in this memo.
Separated endpoint refers to independent SIP User Agent and XMPP
client implementations that are not aware of each other if they
are used by the same user. The users use SIP UA for voice and
video, while using XMPP client for IM and presence. It is assumed
that a separated endpoint does not support any SIP or XMPP
protocol extensions defined in this memo.
3. Deployment scenarios and use cases
This section presents the assumptions we make about SIP and XMPP
deployments with respect to endpoints and server infrastructure. We
also enumerate the actual use cases that the combined service must
accommodate for.
3.1. Deployment scenarios
We assume that the server infrastructures for SIP and XMPP are
totally separated, thus no exchange of information is expected
between these. We do not even assume that SIP and XMPP services are
offered by the same service provider. This means that the user
identities can belong to two different domains. However, if the same
service provider offers both SIP and XMPP service, it is recommended
that the URIs sip:user@domain and xmpp:user@domain correspond to the
same user.
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We assume that the user initially only knows the contact address of
the other user in one protocol space. The contact address for the
other protocol must be learned through this.
We consider only cases where two integrated endpoints interact. When
an integrated endpoint communicates with a separated endpoint, normal
SIP and XMPP procedures apply and no extensions defined in this memo
are used.
3.2. Use cases
o Two users who both use an integrated endpoint start an (XMPP) IM
conversation. After the exchange of initial messages, their UIs
show that the other party is capable of (SIP) voice and/or video
in addition to IM. Either user can at any point add voice and/or
video component to the conversation in such a way that it ends up
in the same endpoint and conversation context where the IM
exchange is already taking place. (Note that for this use case
the conversation initiator initially only needs to know the other
user's XMPP user id.)
o Two users who both use an integrated endpoint start a (SIP) voice
and/or video call. As the call is established, their UIs show
that the other party is capable for (XMPP) IM. Either user can at
any point add an IM component to the conversation in such a way
that it ends up in the same endpoint and conversation context
where the voice and/or video call is already taking place. (Note
that for this use case the caller initially only needs to know the
other user's SIP user id.)
It is possible to vary the two cases above so that one of the
users initiates a "multimedia call" to the other one, i.e. SIP
voice and/or video and XMPP IM are all active from the start.
Technically this happens according to the two-phased approach
above, and it invisible from the end-user.
o A user of an integrated endpoint is able to publish her SIP voice
and video related presence status as part of her XMPP presence.
The status includes information such as user's SIP contact address
(for the integrated endpoint), media capability and availability
and whether the user is currently on the phone. Another user of
an integrated endpoint can see the presence status (assuming she
is authorized for that) and based on that initiate calls. For
instance watcher's UI can now for certain show that the user on
her roster is capable of receiving multimedia calls. (Note that
the watcher initially only needs to know the other user's XMPP
user id.)
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OPEN ISSUE: Is there a use case for discovering other user's XMPP
identity based on her SIP identity without needing to establish a
media session. SIP OPTIONS would be one possibility for that (as
we do not assume SIP presence support).
4. Requirements
This section presents the protocol requirements.
REQ-1: It must be possible for the sender of an XMPP message to
include its SIP contact information within the message. The
contact information must allow the recipient to establish the
SIP session such that the session is routed to the same
endpoint which is hosting the XMPP conversation. As
including the same information in every message would create
some overhead, it is desirable to be able to convey the
contact only once per IM conversation/thread.
REQ-2: It must be possible for the caller to convey in the SIP
session initiation information which allows the callee to
correlate the session with an ongoing XMPP conversation.
REQ-3: It must be possible for the SIP User Agent Client and User
Agent Server that establish a real-time media session to
exchange their XMPP contact information so that either
endpoint can at any time send XMPP messages to the other
endpoint.
REQ-4: It must be possible for the sender to convey in the XMPP
message information which allows the recipient to correlate
the message with an ongoing SIP session.
REQ-5: It must be possible to include SIP real-time media related
contact and status in XMPP presence information. The
information must contain at least SIP contact address to
identify a user or a user agent instance, media capabilities
and general availability status
OPEN ISSUE: Should we define requirements related to error or
corner cases here. For instance what happens to communication
attempts after the other party has closed the conversation
context, e.g. a correlated XMPP message that is sent after the
related SIP session is terminated. Or a SIP INVITE that appears
two days after the XMPP IM conversation was ended.
NOTE: There is also an implicit requirement that we must take
Session Border Controllers into account when defining how SIP User
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Agents are able to identify an existing session between them in a
common manner.
5. Overview of operation
Both SIP and XMPP allow registration of multiple endpoints using the
same identifier, either a SIP AOR or XMPP Jabber ID (JID). When two
endpoints are engaged in an IM conversation, for example, and wish to
add a voice component to the communication, it has to be ensured that
the resulting SIP dialog is targeted to the same endpoint that is
running the IM conversation. Fortunately, both XMPP and SIP provide
a mechanism for this.
[I-D.ietf-sip-gruu] defines mechanisms for a SIP UA to obtain and use
a Globally Routable User Agent (UA) URI, or GRUU. A GRUU will route
a call to a specific UA instance. Unfortunately, not all SIP
registrars support the optional GRUU mechanism. In that case the SIP
UA has not other option but to use its AOR in place of GRUU.
In XMPP, a "full JID" consists of a name, domain and a resource
identifier in the form of <name@domain/resource>. The resource
identifier can be used to identify a specific endpoint.
5.1. Endpoints engaged in XMPP conversation adding a SIP session
Bob Alice
| |
| IM session |
|<=====================>|
| |
| (F1) INVITE |
|---------------------->|
| |
| (F2) 200OK |
|<----------------------|
| |
| (F3) ACK |
|---------------------->|
| |
| RTP media |
|<=====================>|
| |
This case starts by one endpoint (Bob) sending a message stanza to
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another (Alice). Bob includes a <thread> element in the message and
chooses a unique value for it. In his first message Bob also
includes his SIP URI in <sip-contact> element, defined in
Section 6.1. If Bob has been able to obtain a GRUU from his
registrar, he populates the <sip-contact> with that. Otherwise a
mere AOR is used. When Alice receives Bob's SIP URI Alice stores it
associated with the current <thread>. When responding to Bob's
messages Alice also includes a <thread> element and her SIP URI (GRUU
or AOR) in <sip-contact>. Upon receiving Alice's first message Bob
stores Alice's SIP URI associated with the current <thread>. In
addition to containing a SIP URI, <sip-contact> also conveys the
information whether an endpoint supports audio or video or both
medias. So, based on exchanged <sip-contact> elements, both
endpoints now know each others SIP URIs and media capabilities.
The same <thread> value is used in all further messages by both
endpoints to keep track of the conversation. As long as the <thread>
value is unchanged, the <sip-contact> element need not be repeated,
unless either endpoint's SIP GRUU changes for some reason.
When either party wants to extend the IM conversation by adding SIP
voice or video session, they address a SIP INVITE to the SIP URI
learned in <sip-contact>. If the <sip-contact> element contained a
GRUU, it ensures that the INVITE will be routed to the correct
endpoint. The caller populates an XMPP-Thread header, defined in
Section 6.3.1, in the INVITE with the value of <thread>. The callee
is thus able to correlate the SIP session to the IM conversation.
The callee replays XMPP-Thread in responses to INVITE to indicate
that the correlation was successful.
5.2. Endpoints engaged in a SIP session adding an XMPP IM conversation
In this case two endpoints first have a SIP voice or video session.
They exchange their full JIDs within the session establishment: the
caller (Bob) adds XMPP-Contact header, defined in Section 6.3.2, in
INVITE populating it with his full JID. XMPP-Contact also includes
an opaque end-to-end identifier for the session common to both
endpoints. The callee (Alice) stores this information as part of the
session state. In 200 OK response to INVITE Alice includes similar
XMPP-Contact header with her full JID, and replays the end-to-end
session identifier. Bob stores this information as part of his
session state. Both endpoints now know each others full JIDs and
have a common reference to the session.
OPEN ISSUE: Instead of defining XMPP-specific session identifier
we could use SIP call-id as is. However, there is a concern that
call-id may be changed by SBCs en route is thus might not be a
useful as a common reference for both User Agents.
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[I-D.kaplan-sip-session-id] defines a Session-ID header that
potentially could also be used.
When either endpoint wants to send XMPP messages to each other, they
address them to the full JID learned from XMPP-Contact header. This
ensures that the messages reach the correct endpoint. In the very
first message the sender also includes <sip-correlation> element,
defined in Section 6.1, with the session identifier value learned
from XMPP-Contact. The recipient uses the value to correlate the
message with the SIP session and echoes it back the first message it
sends to indicate that the correlation was successful.
5.3. Using XMPP presence for publishing and obtaining SIP contact
address, media capabilities and availability
SIP related presence information is encoded in XMPP presence schema
as an extension. It includes endpoints SIP URI (preferably GRUU but
can be also AOR), media capabilities (audio, video), and availability
(open, closed, busy). Based on this information XMPP Presence
watcher is able to initiate SIP voice and video sessions.
6. Protocol extensions
In this section we define protocol extensions to meet the
requirements stated in the previous section.
6.1. Extensions to XMPP message stanza
The child elements of the message stanza can be extended with
elements from other namespaces. For the purposes of carrying a SIP
identifier in the message stanza, we define two new elements, the
<sip-contact> element and <sip-correlation> element.
6.1.1. The <sip-contact> element
The <sip-contact> element, qualified by urn:xmpp:sip-contact
namespace, has one mandatory attribute, "target", which defines the
target's SIP URI. The format of the "target" attribute is an
absoluteURI defined in [RFC3261].
When an endpoint initiates an XMPP IM conversation, and wants to
offer a possibility to later add a SIP real-time media session, it
MUST include a <sip-contact> element as a child element in the first
the <message> stanza it sends, and MUST add a <thread> element and
populate its value according to [RFC3921]. The endpoint MUST include
in the "target" attribute of the <sip-contact> element the SIP URI it
wishes to be contacted at. If the endpoint is aware of its GRUU, it
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SHOULD use that as the value in the target attribute; otherwise it
MAY use its AOR.
The endpoint receiving an XMPP <message> stanza that includes
<thread> and <sip-contact> elements MUST copy the <thread> element
value to the first <message> stanza it sends back, as defined in
[RFC3921], and MUST include a <sip-contact> element and set the
"target" attribute value to the SIP URI it wishes to be contacted at.
An endpoint MUST add its audio and video capabilities defined in
[RFC3840] to the contact address in the "target" attribute, and MUST
understand those capabilities if received from the other endpoint.
An endpoint MAY add other media capabilities.
When an endpoint receives a <sip-contact> element in a <message>
stanza, it MUST store the value of the target attribute, and use it
as the SIP URI in an INVITE request if the user of the endpoint would
like to add a SIP session to the IM conversation context
For example, a <sip-contact> element carrying a SIP Globally Routable
Unique URI (GRUU) would be
<sip-contact target='Usip:alice@example.com;
gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6;
audio;videoW'>
6.1.2. The <sip-correlation> element
In order to indicate that an XMPP IM conversation is related to an
existing SIP session, we define a new element in the message stanza
called <sip-correlation>. The <sip-correlation>, qualified by the
urn:xmpp:sip-correlation namespace, has one mandatory attribute,
"value".
The endpoint sending the <message> stanza MUST set the "value"
attribute to the value of the correlation-value parameter of the SIP
XMPP-Contact header, defined in Section 6.3.2. The XMPP-Contact
header is exchanged during the setup of the SIP session.
An endpoint receiving a <message> stanza which includes a <sip-
correlation> element MUST first compare the "from" attribute value of
the <message> stanza to the XMPP JID in the contact-value of the
XMPP-Contact header of its active SIP sessions. If a matching SIP
session is found, the endpoint then MUST compare the "value"
attribute of the <sip-correlation> element to the correlation-value
of the XMPP-Contact header of that SIP session. If the "value"
attribute matches to correlation-value of an XMPP-Contact header, the
<message> stanza is correlated to that SIP session. If the user
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replies to the message, the values of the <thread> element and the
"value" attribute of the <sip-correlation> element in the first reply
MUST be the same as in the original message. This indicates that the
correlation was successful. The correlation is valid as long as the
messages are exchanged with the same <thread> value.
As an example, consider a case where a SIP session was set up, and
during that time one of the endpoints included a XMPP-Contact header
with the correlation-value parameter set to the value 'xyz123'. Now,
when the same endpoint wishes to add an XMPP IM session, it would add
a <sip-correlation> element in the message stanza carrying the same
value in the "value" attribute:
<sip-correlation value='xyz123'/>
OPEN ISSUE: XML Schemas to be provided
6.2. Extensions to XMPP presence stanza
The XMPP presence stanza defined in [RFC3921] can be extended with
any properly-namespaced child element. We define a new optional
element called <contact> which, qualified by the urn:xmpp:contact
namespace, MAY appear as a child element in the presence stanza.
The contact element SHOULD be set to the SIP address (GRUU or AOR)
the endpoint wishes to be contacted at for further communication.
Exact syntax and XML Schema of the correlation element is TBD.
6.3. Extensions to SIP headers
6.3.1. SIP XMPP-Thread header
In order to indicate that the SIP dialog is related to an existing
XMPP messaging session, we define a new SIP header, called XMPP-
Thread. The XMPP-Thread contains information that can be used by the
terminating endpoint to correlate the SIP session establishment to an
existing XMPP conversation.
The endpoint sending a SIP INVITE request MUST include an XMPP-Thread
header, and set its value to the value of the <thread> element used
in the XMPP IM conversation.
The endpoint receiving a SIP INVITE which includes an XMPP-Thread
header acts as follows:
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o it first compares the Contact header value with all SIP GRUUs from
<sip-contact> elements in active XMPP IM conversations, and unless
a match is found,
o compares P-Asserted-Identity header value with all other SIP URIs
from <sip-contact> elements in active XMPP IM conversations
o if a single match is found, the receiving endpoint MUST compare
the value of the XMPP-Thread element to the <thread> element
values of existing XMPP IM conversations the endpoint has active,
and
o if the value matches, the SIP INVITE is correlated to the IM
conversation. The endpoint MUST copy the XMPP-Thread header to
any of the 2xx series responses.
Figure 1 defines support of XMPP-Contact header in SIP requests and
responses, and extends Table 2 of [RFC3261]. MESSAGE, SUBCRIBE and
NOTIFY, REFER, INFO, UPDATE, PRACK, and PUBLISH are defined in
[RFC3428], [RFC3265], [RFC3515], [RFC2976], [RFC3311], [RFC3262], and
[RFC3903], respectively.
Header field where proxy ACK BYE CAN INV OPT REG MSG
------------ ----- ----- --- --- --- --- --- --- ---
XMPP-Thread R - - - o - - -
XMPP-Thread 2xx - - - o - - -
SUB NOT REF INF UPD PRA PUB
--- --- --- --- --- --- ---
XMPP-Thread R - - - - - - -
XMPP-Thread 2xx - - - - - - -
Figure 1: XMPP-Thread header support
The syntax of the XMPP-Thread using augmented Backur-Naur Form (ABNF)
[RFC5234] is defined as follows:
XMPP-Thread = "XMPP-Thread" HCOLON thread-value
thread-value = token
;defined in RFC3261
6.3.2. SIP XMPP-Contact header
The XMPP-Contact header is used to carry the XMPP JID and an opaque
token that can be used for correlation purposes.
When an endpoint initiates a SIP session, and wants to offer the
possibility to later add an XMPP IM conversation, it MUST include an
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XMPP-Contact header in the initial SIP request. The contact-value of
the XMPP-Contact header MUST be set to the full XMPP JID the endpoint
wishes to be contacted at, and the correlation-value SHOULD be set to
the value of the Call-ID of the SIP session. If the Call-ID cannot
be used, the endpoint MUST select the correlation-value such that it
fulfills the same uniqueness requirements defined for Call-ID in
Section 8.1.1.4 of [RFC3261].
An endpoint sending a 2xx series response to an INVITE that contains
XMPP-Contact header MUST include a XMPP-Contact header in the
response, MUST set the contact-value of the header to the full XMPP
JID the endpoint wishes to be contacted at, and MUST copy the
correlation-value from the INVITE to the 2xx response.
The endpoint receiving a SIP request or response with an XMPP-Contact
header, MUST store the value of the correlation-value as part of the
session state in order to be able to later correlate an XMPP IM
conversation with the SIP session.
Figure 2 defines support of XMPP-Contact header in SIP requests and
responses, and extends Table 2 of [RFC3261]. MESSAGE, SUBCRIBE and
NOTIFY, REFER, INFO, UPDATE, PRACK, and PUBLISH are defined in
[RFC3428], [RFC3265], [RFC3515], [RFC2976], [RFC3311], [RFC3262], and
[RFC3903], respectively.
Header field where proxy ACK BYE CAN INV OPT REG MSG
------------ ----- ----- --- --- --- --- --- --- ---
XMPP-Contact R - - - o - - -
XMPP-Contact 2xx - - - o - - -
SUB NOT REF INF UPD PRA PUB
--- --- --- --- --- --- ---
XMPP-Contact R - - - - - - -
XMPP-Contact 2xx - - - o - - -
Figure 2: XMPP-Contact header field support
The syntax of the XMPP-Contact using augmented Backur-Naur Form
(ABNF) [RFC5234] is defined as follows:
XMPP-Contact = "XMPP-Contact" HCOLON contact-value SEMI correlation-value
contact-value = token
;defined in RFC3261
correlation-value =token
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7. Examples
7.1. Endpoint engaged in an IM session adds a voice/video component to
the conversation
Bob Alice
| |
| (F1) <message> |
|---------------------->|
| |
| (F2) <message> |
|<----------------------|
| |
| (F3) INVITE |
|---------------------->|
| |
| (F4) 200OK |
|<----------------------|
| |
| (F5) ACK |
|---------------------->|
| |
| RTP media |
|<=====================>|
| |
SIP voice session added to XMPP IM conversation
Bob and Alice are engaged in an XMPP IM session, when Bob would like
to add voice/video component to the discussion.
When Bob and Alice exchange message stanzas, they also include the
SIP address they would like to be contacted at. In this example, Bob
is aware of its GRUU, while Alice is merely aware of her SIP AOR.
Both include the SIP identifier in a contact element in the message
stanza.
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<message
to='alice@example.net'
from='bob@domain.com/Home'
type='chat'
xml:lang='en'>
<body>Hi!</body>
<thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
<sip-contact target='Usip:bob@domain.com;gr=urn:
uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6;
audio;videoW'
xmlns=urn:xmpp:sip-contact/>
</message>
(F1) Bob sends a message stanza to
Alice
In the above message, Bob includes his GRUU, and also the media
capabilities Bob is capable of handling (audio and video).
Alice sends back a message stanza containing her SIP contact
information.
<message
to='bob@domain.com/Home'
from='alice@example.net/4FIL45729'
type='chat'
xml:lang='en'>
<body>Hello there!</body>
<thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
<sip-contact target='Usip:alice@example.netWaudio;video'
xmlns=urn:xmpp:sip-contact/>
</message>
(F2) Alice sends a message stanza to
Bob
Bob then decides to add SIP voice call to the existing XMPP
conversation. He picks up Alice's contact information that Alice
sent to him in a message stanza, and issues a SIP INVITE request to
that URI. The XMPP-Thread carries the value of the <thread> element.
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INVITE sip:alice@example.net SIP/2.0
Via: SIP/2.0/UDP ua-991.domain.com;branch=apo92hgb2k100
Max-Forwards: 70
To: Alice <sip:alice@example.com>
From: Bob <sip:bob@domain.com>;tag=18593756298
Call-ID: a84b4c76e66710@ua-991.domain.com
CSeq: 314159 INVITE
XMPP-Thread:e0ffe42b28561960c6b12b944a092794b9683a38
Contact: <sip:bob@domain.com;gr=urn:
uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6;
audio;video>
Content-Type: application/sdp
Content-Length: 142
(SDP not shown)
(F3) Bob sends a SIP INVITE to
Alice
Alice responds with 200 OK accepting the session invitation request.
Alice also includes the XMPP-Thread element to indicate that she has
received the thread and successfully correlated the session
invitation to the XMPP conversation.
SIP/2.0 200 OK
Via: SIP/2.0/UDP p1.example.com
;branch=z9hG4bKnashds8;received=192.0.2.3
Via: SIP/2.0/UDP p1.domain.com
;branch=z9hG4bKnashds8;received=192.0.2.2
Via: SIP/2.0/UDP ua-991.domain.com
;branch=apo92hgb2k100;received=192.0.2.1
Max-Forwards: 70
To: Alice <sip:alice@example.com>;tag=c09hh1lsn
From: Bob <sip:bob@domain.com>;tag=18593756298
Call-ID: a84b4c76e66710@ua-991.domain.com
CSeq: 314159 INVITE
XMPP-Thread:e0ffe42b28561960c6b12b944a092794b9683a38
Contact: <sip:alice@192.0.2.4>
Content-Type: application/sdp
Content-Length: 131
(SDP not shown)
(F4) Alice accepts the session and sends a 200OK
to Bob
Bob then sends a ACK as per normal SIP procedures.
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7.2. Endpoint engaged in a SIP session adds an XMPP IM conversation
Bob Alice
| |
| |
| (F1) INVITE |
|---------------------->|
| |
| (F2) 200OK |
|<----------------------|
| |
| (F3) ACK |
|---------------------->|
| |
| RTP media |
|<=====================>|
| |
| (F4) <message> |
|---------------------->|
| |
| (F5) <message> |
|<----------------------|
XMPP IM conversation added to SIP voice
session
Bob invites Alice to a SIP session. In the INVITE request, Bob
includes the XMPP-Contact header including his XMPP JID.
INVITE sip:alice@example.net SIP/2.0
Via: SIP/2.0/UDP ua-991.domain.com;branch=apo92hgb2k100
Max-Forwards: 70
To: Alice <sip:alice@example.com>
From: Bob <sip:bob@domain.com>;tag=18593756298
Call-ID: a84b4c76e66710@ua-991.domain.com
CSeq: 314159 INVITE
XMPP-contact:<xmpp:bob@domain.com/home>
;a84b4c76e66710@ua-991.domain.com
Contact: <sip:bob@domain.com;gr=urn:
uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6;
audio;video>
Content-Type: application/sdp
Content-Length: 142
(SDP not shown)
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(F1) Bob sends a SIP INVITE to
Alice
SIP/2.0 200 OK
Via: SIP/2.0/UDP p1.example.com
;branch=z9hG4bKnashds8;received=192.0.2.3
Via: SIP/2.0/UDP p1.domain.com
;branch=z9hG4bKnashds8;received=192.0.2.2
Via: SIP/2.0/UDP ua-991.domain.com
;branch=apo92hgb2k100;received=192.0.2.1
Max-Forwards: 70
To: Alice <sip:alice@example.com>;tag=c09hh1lsn
From: Bob <sip:bob@domain.com>;tag=18593756298
Call-ID: a84b4c76e66710@ua-991.domain.com
CSeq: 314159 INVITE
XMPP-Contact:<xmpp:alice@example.com/4FIL45729>
;a84b4c76e66710@ua-991.domain.com
Contact: <sip:alice@192.0.2.4>
Content-Type: application/sdp
Content-Length: 131
(SDP not shown)
(F2) Alice accepts the session and sends a 200OK
to Bob
<message
to='alice@example.net'
from='bob@domain.com/Home'
type='chat'
xml:lang='en'>
<body>Hi!</body>
<thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
<sip-correlation value='a84b4c76e66710@ua-991.domain.com'>
</message>
(F4) Bob sends a message to
Alice
Alice sends back a message stanza copying the sip-correlation value
indicating the the correlation was successful.
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<message
to='bob@domain.com/Home'
from='alice@example.net'
type='chat'
xml:lang='en'>
<body>Hello there!</body>
<thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
<sip-correlation value='a84b4c76e66710@ua-991.domain.com'>
</message>
(F5) Alice sends a message stanza to
Bob
8. IANA Considerations
TBD
9. Security Considerations
The contact and correlation information is sensitive and we need to
prevent connection hijacking and impersonation. If the contact
information that is sent over one protocol is forged, the identity
verification mechanism in the other no longer help as an attacker is
able to assert the false identity.
10. Acknowledgments
TBD
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2976] Donovan, S., "The SIP INFO Method", RFC 2976,
October 2000.
[RFC3261] 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.
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[RFC3262] Rosenberg, J. and H. Schulzrinne, "Reliability of
Provisional Responses in Session Initiation Protocol
(SIP)", RFC 3262, June 2002.
[RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific
Event Notification", RFC 3265, June 2002.
[RFC3311] Rosenberg, J., "The Session Initiation Protocol (SIP)
UPDATE Method", RFC 3311, October 2002.
[RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
and D. Gurle, "Session Initiation Protocol (SIP) Extension
for Instant Messaging", RFC 3428, December 2002.
[RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer
Method", RFC 3515, April 2003.
[RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
"Indicating User Agent Capabilities in the Session
Initiation Protocol (SIP)", RFC 3840, August 2004.
[RFC3903] Niemi, A., "Session Initiation Protocol (SIP) Extension
for Event State Publication", RFC 3903, October 2004.
[RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 3920, October 2004.
[RFC3921] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Protocol (XMPP): Instant Messaging and Presence",
RFC 3921, October 2004.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
11.2. Informative References
[I-D.ietf-sip-gruu]
Rosenberg, J., "Obtaining and Using Globally Routable User
Agent (UA) URIs (GRUU) in the Session Initiation Protocol
(SIP)", draft-ietf-sip-gruu-15 (work in progress),
October 2007.
[I-D.kaplan-sip-session-id]
Kaplan, H., "A Session Identifier for the Session
Initiation Protocol (SIP)", draft-kaplan-sip-session-id-02
(work in progress), March 2009.
[I-D.saintandre-sip-xmpp-core]
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Saint-Andre, P., Houri, A., and J. Hildebrand,
"Interworking between the Session Initiation Protocol
(SIP) and the Extensible Messaging and Presence Protocol
(XMPP): Core", draft-saintandre-sip-xmpp-core-01 (work in
progress), March 2009.
Authors' Addresses
Simo Veikkolainen
Nokia
P.O. Box 407
NOKIA GROUP, FI 00045
Finland
Phone: +358 50 486 4463
Email: simo.veikkolainen@nokia.com
Markus Isomaki
Nokia
P.O. Box 100
NOKIA GROUP, FI 00045
Finland
Phone: +358 50 522 5984
Email: markus.isomaki@nokia.com
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