git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@762 4b5297f7-1745-476d-ba37-a9c6900126ab
xep-0352-v0.2
Peter Saint-Andre 2007-04-17 21:07:23 +00:00
parent 5bff624496
commit 78269e486d
1 changed files with 141 additions and 39 deletions

View File

@ -2,7 +2,8 @@
<!DOCTYPE xep SYSTEM 'xep.dtd' [
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
<!ENTITY icecurr "<cite>ICE-14</cite>">
<!ENTITY icecurr "<cite>ICE-CORE</cite>">
<!ENTITY icetcp "<cite>ICE-TCP</cite>">
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
@ -27,6 +28,12 @@
&scottlu;
&hildjj;
&seanegan;
<revision>
<version>0.8</version>
<date>2007-04-17</date>
<initials>psa</initials>
<remark><p>Separately defined ice-tcp and ice-udp transport methods to enable clearer definition of transport methods and reuse by application types; specified Jingle conformance, including definition of ice-udp as lossy and ice-tcp as reliable.</p></remark>
</revision>
<revision>
<version>0.7</version>
<date>2007-03-23</date>
@ -71,29 +78,39 @@
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>&xep0166; defines a framework for negotiating and managing out-of-band data sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor content formats, leaving that up to separate specifications. The current document defines a transport method for establishing and managing data connections between XMPP entities, using the ICE methodology currently being developed within the IETF.</p>
<p>&xep0166; defines a framework for negotiating and managing out-of-band data sessions over XMPP. In order to provide a flexible framework, the base Jingle specification defines neither data transport methods nor content formats, leaving that up to separate specifications. The current document defines two transport methods (ice-udp and ice-tcp) for establishing and managing data connections between XMPP entities, using the ICE methodology currently being developed within the IETF. The ice-udp method results in a lossy transport suitable for use in media applications where some packet loss is tolerable (e.g., audio and video), whereas the ice-tcp method results in a reliable transport suitable for use in applications where packet loss is not tolerable (e.g., file transfer).</p>
<p>The process for ICE negotiation is largely the same in Jingle as it is in &icecurr;. There are several differences:</p>
<ul>
<li>Instead of using SIP as the signalling channel, Jingle uses XMPP as the signalling channel.</li>
<li>In Jingle, each candidate transport is sent in a separate IQ exchange (rather than sending all candidates at once as in &icecurr;); this approach takes advantage of the request-response semantics of the XMPP &IQ; stanza type and enables the parties to send higher-priority candidates earlier in the negotiation.</li>
<li>Syntax from the Session Description Protocol (see &rfc4566;) is mapped to an XML syntax suitable for sending over the XMPP signalling channel.</li>
</ul>
<p><em>Note: This document depends on the IETF's &ice; specification, which is a work in progress. Every effort has been made to keep this document synchronized with <cite>draft-ietf-mmusic-ice</cite>, for which the latest published version is 14 (hereafter referred to as "&icecurr;"). The interested reader is referred to &icecurr; for a detailed description of the ICE methodology, which for the most part this document merely maps to XMPP syntax.</em></p>
<p><em>Note: This document depends on the IETF's &ice; specification, which is a work in progress. Every effort has been made to keep this document synchronized with <cite>draft-ietf-mmusic-ice</cite>, for which the latest published version is 15 (hereafter referred to as "&icecurr;"). The interested reader is referred to &icecurr; for a detailed description of the ICE methodology, which for the most part this document merely maps to XMPP syntax.</em></p>
</section1>
<section1 topic='Glossary' anchor='terms'>
<p>The reader is referred to &icecurr; and &icetcp; for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
<p>The Jingle transport method defined herein is designed to meet the following requirements:</p>
<p>The Jingle transport methods defined herein is designed to meet the following requirements:</p>
<ol>
<li>Make it possible to establish and manage out-of-band connections between two XMPP entities, even if they are behind Network Address Translators (NATs) or firewalls.</li>
<li>Enable use of either UDP (see &icecurr;) or TCP (see &ice-tcp;) as the transport protocol itself.</li>
<li>Make it relatively easy to implement support in standard Jabber/XMPP clients.</li>
<li>Where communication with non-XMPP entities is needed, push as much complexity as possible onto server-side gateways between the XMPP network and the non-XMPP network.</li>
</ol>
</section1>
<section1 topic='Glossary' anchor='terms'>
<p>The reader is referred to &icecurr; for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
<section1 topic='Jingle Conformance' anchor='conformance'>
<p>In accordance with Section 8 of <cite>XEP-0166</cite>, this document specifies the following information related to the Jingle ice-udp and ice-tcp transport types:</p>
<ol>
<li><p>The transport negotiation process is defined in the <link url='#protocol'>Protocol Description</link> section of this document.</p></li>
<li><p>The semantics of the &DESCRIPTION; element are defined in the <link url='#initiate'>Transport Initiation</link> section of this document.</p></li>
<li><p>Successful negotiation of the ice-udp method results in use of a lossy transport that is suitable for applications where some packet loss is tolerable, such as audio and video; successful negotiation of the ice-tcp method results in use of a reliable transport that is suitable for applications where packet loss is not tolerable, such as file transfer.</p></li>
<li><p>If multiple components are to be communicated over the transport in the context of the Real-time Transport Protocol (RTP; see &rfc3550;), the component numbered "1" shall be associated with RTP and the component numbered "2" shall be associated with the Real Time Control Protocol (RTCP).</p></li>
</ol>
</section1>
<section1 topic='Protocol Description' anchor='protocol'>
<section2 topic='Transport Initiation' anchor='protocol-initiate'>
<p>In order for the initiator in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in <cite>XEP-0166</cite>. This stanza MUST include at least one transport method. If the initiator wishes to negotiate the ICE transport, it MUST include an empty &TRANSPORT; child element qualified by the 'http://www.xmpp.org/extensions/xep-0176.html#ns' namespace &NSNOTE;.</p>
<p>In order for the initiator in a Jingle exchange to start the negotiation, it MUST send a Jingle "session-initiate" stanza as described in <cite>XEP-0166</cite>. This stanza MUST include at least one transport method. If the initiator wishes to negotiate the ice-udp or ice-tcp transport, it MUST include an empty &TRANSPORT; child element qualified by the 'http://www.xmpp.org/extensions/xep-0176.html#ns-udp' or 'http://www.xmpp.org/extensions/xep-0176.html#ns-tcp' namespace &NSNOTE;.</p>
<example caption="Initiation"><![CDATA[
<iq to='juliet@capulet.com/balcony' from='romeo@montague.net/orchard' id='jingle1' type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
@ -104,7 +121,7 @@
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
...
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'/>
</content>
</jingle>
</iq>
@ -118,7 +135,7 @@
</section2>
<section2 topic='ICE Negotiation' anchor='protocol-negotiate'>
<p>If the responder provisionally accepts the session initiation request as shown above, both initiator and responder MUST immediately negotiate connectivity over the ICE transport by exchanging XML-formatted candidate transports for the channel. This negotiation proceeds immediately in order to maximize the possibility that media can be exchanged as quickly as possible. <note>Concurrent with negotiation of the ICE candidates, it is possible for the initiator and responder to negotiate which content types the session will include, which transport methods will be tried for each content type, etc. Those negotiation flows are shown in <cite>XEP-0166</cite>. This document specifies only negotiation of the ICE transport method.</note></p>
<p>The candidate syntax and negotiation flow are described below.</p>
<p>The candidate syntax and negotiation flow are described below. (This document shows negotiation for the ice-udp transport method, but the same principles apply to the ice-tcp transport method.)</p>
<section3 topic='Syntax of Candidate Element' anchor='protocol-negotiate-candidate'>
<p>The following is an example of the candidate format:</p>
<example caption="Initiator Sends a Candidate Transport"><![CDATA[
@ -128,7 +145,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='0'
@ -199,7 +216,7 @@
</tr>
<tr>
<td>protocol</td>
<td>The protocol to be used. The allowable values are: "udp" (when standard &icecurr; is used); "tcp-act", "tcp-pass", and "tcp-so" (when &ice-tcp; is used); and "ssltcp" (definition to follow in a separate specification).</td>
<td>The protocol to be used. The allowable values are: "udp" (when the ice-udp transport method is used); "tcp-act", "tcp-pass", and "tcp-so" (when the ice-tcp transport method is used); in addition, future specifications may specify other allowable values.</td>
<td>Transport protocol field in a=candidate line</td>
<td>udp</td>
</tr>
@ -237,7 +254,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='1'
foundation='1'
generation='0'
@ -261,7 +278,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='2'
foundation='1'
generation='0'
@ -285,7 +302,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='2'
foundation='1'
generation='0'
@ -322,7 +339,7 @@
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='2'
foundation='1'
generation='0'
@ -354,7 +371,7 @@
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='2'
foundation='1'
generation='0'
@ -379,7 +396,7 @@
</section1>
<section1 topic='Determining Support' anchor='support'>
<p>If an entity supports the Jingle ICE transport, it MUST return a feature of "http://www.xmpp.org/extensions/xep-0176.html#ns" &NSNOTE; in response to &xep0030; information requests.</p>
<p>If an entity supports the Jingle ice-udp transport, it MUST return a feature of "http://www.xmpp.org/extensions/xep-0176.html#ns-udp" &NSNOTE; in response to &xep0030; information requests.</p>
<example caption="Service Discovery information request"><![CDATA[
<iq type='get'
from='romeo@montague.net/orchard'
@ -395,7 +412,28 @@
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'/>
...
</query>
</iq>
]]></example>
<p>If an entity supports the Jingle ice-tcp transport, it MUST return a feature of "http://www.xmpp.org/extensions/xep-0176.html#ns-tcp" &NSNOTE; in response to &xep0030; information requests.</p>
<example caption="Service Discovery information request"><![CDATA[
<iq type='get'
from='romeo@montague.net/orchard'
to='juliet@capulet.com/balcony'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
]]></example>
<example caption="Service Discovery information response"><![CDATA[
<iq type='result'
from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='disco1'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'/>
...
</query>
</iq>
@ -419,15 +457,29 @@
<p>Until this specification advances to a status of Draft, its associated namespace shall be "http://www.xmpp.org/extensions/xep-0176.html#ns"; upon advancement of this specification, the &REGISTRAR; shall issue a permanent namespace in accordance with the process defined in Section 4 of &xep0053;.</p>
</section2>
<section2 topic='Jingle Transport Methods' anchor='registrar-transports'>
<p>The XMPP Registrar shall include "ice" in its registry of Jingle transport methods. The registry submission is as follows:</p>
<p>The XMPP Registrar shall include "ice-udp" and "ice-tcp" in its registry of Jingle transport methods. The registry submission is as follows:</p>
<code><![CDATA[
<transport>
<name>ice</name>
<name>ice-tcp</name>
<desc>
A method for negotiation of out-of-band connections with built-in NAT and firewall
traversal, equivalent to the IETF's Interactive Connectivity Establishment (ICE)
methodology.
A method for negotiation of out-of-band TCP connections with built-in NAT
and firewall traversal, equivalent to the IETF's Interactive Connectivity
Establishment (ICE) methodology when resulting in the use of TCP as the
transport protocol.
</desc>
<type>reliable</type>
<doc>XEP-0176</doc>
</transport>
<transport>
<name>ice-udp</name>
<desc>
A method for negotiation of out-of-band UDP connections with built-in NAT
and firewall traversal, equivalent to the IETF's Interactive Connectivity
Establishment (ICE) methodology when resulting in the use of UDP as the
transport protocol.
</desc>
<type>lossy</type>
<doc>XEP-0176</doc>
</transport>
]]></code>
@ -435,13 +487,14 @@
</section1>
<section1 topic='XML Schemas' anchor='schema'>
<code><![CDATA[
<section2 topic='ICE-TCP Transport Method' anchor='schema-tcp'>
<code><![CDATA[
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://www.xmpp.org/extensions/xep-0176.html#ns'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'
targetNamespace='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'
elementFormDefault='qualified'>
<xs:element name='transport'>
@ -465,19 +518,9 @@
<xs:attribute name='network' type='xs:unsignedByte' use='required'/>
<xs:attribute name='port' type='xs:unsignedShort' use='required'/>
<xs:attribute name='priority' type='xs:positiveInteger' use='required'/>
<xs:attribute name='protocol' use='optional'>
<xs:simpleType>
<xs:restriction base='xs:NCName'>
<xs:enumeration value='ssltcp'/>
<xs:enumeration value='tcp-act'/>
<xs:enumeration value='tcp-pass'/>
<xs:enumeration value='tcp'/>
<xs:enumeration value='udp'/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name='protocol' type='xs:NCName' use='required'/>
<xs:attribute name='pwd' type='xs:string' use='required'/>
<xs:attribute name='type' use='optional'>
<xs:attribute name='type' use='required'>
<xs:simpleType>
<xs:restriction base='xs:NCName'>
<xs:enumeration value='host'/>
@ -500,6 +543,65 @@
</xs:simpleType>
</xs:schema>
]]></code>
]]></code>
</section2>
<section2 topic='ICE-UDP Transport Method' anchor='schema-udp'>
<code><![CDATA[
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'
elementFormDefault='qualified'>
<xs:element name='transport'>
<xs:complexType>
<xs:choice>
<xs:sequence>
<xs:element ref='candidate' minOccurs='0' maxOccurs='1'/>
</xs:sequence>
</xs:choice>
</xs:complexType>
</xs:element>
<xs:element name='candidate'>
<xs:complexType>
<xs:simpleContent>
<xs:extension base='empty'>
<xs:attribute name='component' type='xs:unsignedByte' use='required'/>
<xs:attribute name='foundation' type='xs:unsignedByte' use='required'/>
<xs:attribute name='generation' type='xs:unsignedByte' use='required'/>
<xs:attribute name='ip' type='xs:string' use='required'/>
<xs:attribute name='network' type='xs:unsignedByte' use='required'/>
<xs:attribute name='port' type='xs:unsignedShort' use='required'/>
<xs:attribute name='priority' type='xs:positiveInteger' use='required'/>
<xs:attribute name='protocol' type='xs:NCName' use='required'/>
<xs:attribute name='pwd' type='xs:string' use='required'/>
<xs:attribute name='type' use='required'>
<xs:simpleType>
<xs:restriction base='xs:NCName'>
<xs:enumeration value='host'/>
<xs:enumeration value='prflx'/>
<xs:enumeration value='relay'/>
<xs:enumeration value='srflx'/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name='ufrag' type='xs:string' use='required'/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:simpleType name='empty'>
<xs:restriction base='xs:string'>
<xs:enumeration value=''/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
]]></code>
</section2>
</section1>
</xep>