git-svn-id: file:///home/ksmith/gitmigration/svn/xmpp/trunk@1430 4b5297f7-1745-476d-ba37-a9c6900126ab
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Peter Saint-Andre 2007-11-28 19:30:50 +00:00
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@ -3,13 +3,12 @@
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
<!ENTITY icecore "<cite>ICE-CORE</cite>">
<!ENTITY icetcp "<cite>ICE-TCP</cite>">
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
<title>Jingle ICE Transport Methods</title>
<abstract>This document defines a Jingle transport method that results in sending data between two entities using the Interactive Connectivity Establishment (ICE) methodology.</abstract>
<title>Jingle ICE-UDP Transport Method</title>
<abstract>This document defines a Jingle transport method that results in sending data between two XMPP entities via the User Datagram Protocol (UDP) as negotiated using the Interactive Connectivity Establishment (ICE) methodology.</abstract>
&LEGALNOTICE;
<number>0176</number>
<status>Proposed</status>
@ -23,11 +22,17 @@
<supersedes/>
<supersededby/>
<shortname>TO BE ASSIGNED</shortname>
&stpeter;
&joebeda;
&scottlu;
&stpeter;
&hildjj;
&seanegan;
<revision>
<version>0.12</version>
<date>2007-11-28</date>
<initials>psa</initials>
<remark><p>Moved ice-tcp definition to a separate specification.</p></remark>
</revision>
<revision>
<version>0.11</version>
<date>2007-11-27</date>
@ -96,11 +101,9 @@
</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 application formats, leaving that up to separate specifications. The current document defines two transport methods for establishing and managing data connections between XMPP entities, using the ICE methodology developed within the IETF:</p>
<ol>
<li><p>The <strong>ice-udp</strong> method is an XMPP profile of the core ICE methodology specified in &ice;. The IETF specification in question, hereafter referred to as &icecore;, has been approved for publication as an RFC but has not yet been so published. Use of the ice-udp method results in a lossy transport suitable for media applications where some packet loss is tolerable (e.g., audio and video).</p></li>
<li><p>The <strong>ice-tcp</strong> method is an XMPP profile of the ICE methodology as applied to TCP and specified in &ice-tcp;, hereafter referred to as &icetcp;. The IETF specification in question is still a work in progress. Use of the ice-tcp method results in a reliable transport suitable applications where packet loss is not tolerable (e.g., file transfer).</p></li>
</ol>
<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 application formats, leaving that up to separate specifications.</p>
<p>The current document defines a transport method for establishing and managing data exchanges between XMPP entities over the User Datagram Protocol (see &rfc0768;), using the ICE methodology developed within the IETF and specified in &ice; (hereafter referred to as &icecore;). Use of the <strong>ice-udp</strong> method results in a lossy transport suitable for media applications where some packet loss is tolerable (e.g., audio and video).</p>
<p>Note: &icecore; has been approved for publication as an RFC but has not yet been published as an RFC. While every effort has been made to keep this document synchronized with &icecore;, the interested reader is referred to &icecore; for a detailed description of the ICE methodology.</p>
<p>The process for ICE negotiation is largely the same in Jingle as it is in ICE. There are several differences:</p>
<ul>
<li>Instead of using SIP as the signalling channel, Jingle uses XMPP as the signalling channel.</li>
@ -109,32 +112,31 @@
<li>ICE candidates can be upgraded during a session (e.g., to change an IP address).</li>
<li>Either party can continue to send ICE candidates throughout a session and renegotiate which candidate will be used.</li>
</ul>
<p><em>Note: This document depends the &icecore; and &icetcp; specifications developed by the IETF. While every effort has been made to keep this document synchronized with &icecore; and &icetcp;, the interested reader is referred to &icecore; for a detailed description of the ICE methodology.</em></p>
</section1>
<section1 topic='Glossary' anchor='terms'>
<p>The reader is referred to &icecore; and &icetcp; for a description of various terms used in the context of ICE. Those terms are not reproduced here.</p>
<p>The reader is referred to &icecore; 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 methods defined herein are designed to meet the following requirements:</p>
<p>The Jingle transport method defined herein are 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 &icecore;) or TCP (see &icetcp;) as the transport protocol itself.</li>
<li>Enable use of UDP 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='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 methods:</p>
<p>In accordance with Section 8 of <cite>XEP-0166</cite>, this document specifies the following information related to the Jingle ice-udp transport method:</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 &TRANSPORT; element are defined in the <link url='#protocol-negotiate'>ICE Negotiation</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>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.</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>. A content type MUST include one transport method. If the initiator wishes to negotiate the ice-udp or ice-tcp transport for an application format, 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>
<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>. A content type MUST include one transport method. If the initiator wishes to negotiate the ice-udp transport method for an application format, it MUST include an empty &TRANSPORT; child element qualified by the 'http://www.xmpp.org/extensions/xep-0176.html#ns' namespace &NSNOTE;.</p>
<example caption="Initiation"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='jingle1'
@ -148,7 +150,7 @@
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'/>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
</content>
</jingle>
</iq>
@ -166,7 +168,7 @@
<section2 topic='ICE Negotiation' anchor='protocol-negotiate'>
<p>Once the responder acknowledges receipt of 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 other specifications, such as <cite>XEP-0166</cite>. This document specifies only negotiation of the ICE transport method.</note></p>
<p>Note: In order to expedite session establishment, the initiator MAY send transport candidates immediately after sending the "session-initiate" message and before receiving acknowledgement from the responder (i.e., the initiator MUST consider the session to be live even before receiving acknowledgement). Given in-order delivery, the responder should receive such "transport-info" messages after receiving the "session-initiate" message; if not, it is appropriate for the responder to return &lt;unknown-session/&gt; errors since it according to its state machine the session does not exist. If either party receives an &lt;unknown-session/&gt; from the other party, it MUST terminate the negotiation and the session.</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>
<p>The candidate syntax and negotiation flow are described below.</p>
<section3 topic='Syntax of Candidate Element' anchor='protocol-negotiate-candidate'>
<p>The following is an example of the candidate format:</p>
<example caption="A candidate transport"><![CDATA[
@ -236,7 +238,7 @@
</tr>
<tr>
<td>protocol</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>The protocol to be used. The only allowable value is "udp".</td>
<td>Transport protocol field in a=candidate line</td>
<td>udp</td>
</tr>
@ -261,7 +263,7 @@
</table>
</section3>
<section3 topic='Negotiation Flow' anchor='protocol-negotiate-flow'>
<p>The first step in negotiating connectivity is for both parties to immediately begin sending candidate transport methods to the other client. <note>The fact that both parties send candidates means that Jingle requires each party to be a full implementation of ICE, not a "lite" implementation as specified in &icecore;.</note> These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of &icecore; and prioritized by following the procedure specified in Section 4.1.2 of &icecore;. Each candidate MUST be sent in a &JINGLE; element with an action of "transport-info".</p>
<p>The first step in negotiating connectivity is for both parties to immediately begin sending transport candidates methods to the other client. <note>The fact that both parties send candidates means that Jingle requires each party to be a full implementation of ICE, not a "lite" implementation as specified in &icecore;.</note> These candidates SHOULD be gathered by following the procedure specified in Section 4.1.1 of &icecore; and prioritized by following the procedure specified in Section 4.1.2 of &icecore;. Each candidate MUST be sent in a &JINGLE; element with an action of "transport-info".</p>
<p>If the responder receives and can successfully process a given candidate, it returns an IQ-result (if not, for example because the candidate data is improperly formatted, it returns an error). Note: The responder is only indicating receipt of the candidate, not telling the initiator that the candidate will be used.</p>
<p>The initiator keeps sending candidates, one after the other (without stopping to receive an acknowledgement of receipt from the responder for each candidate) until it has exhausted its supply of possible or desirable candidate transports. (Because certain candidates may be more "expensive" in terms of bandwidth or processing power, the initiator may not want to advertise their existence unless necessary.) For each candidate, the responder acknowledges receipt.</p>
<p>At the same time (i.e., immediately after acknowledging receipt of the session-initiate request, not waiting for the initiator to begin or finish sending candidates), the responder also begins sending potential candidates, in order of desirability according to the responder. As above, the initiator acknowledges receipt of the candidates.</p>
@ -276,7 +278,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -303,7 +305,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -330,7 +332,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -382,7 +384,7 @@
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -434,7 +436,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='1'
@ -473,7 +475,7 @@
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='1'
@ -511,7 +513,7 @@
initiator='romeo@montague.net/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -550,7 +552,7 @@
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
[ ... ]
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'>
<candidate component='1'
foundation='1'
generation='0'
@ -579,7 +581,7 @@
</section1>
<section1 topic='Determining Support' anchor='support'>
<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>
<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" &NSNOTE; in response to &xep0030; information requests.</p>
<example caption="Service discovery information request"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='disco1'
@ -595,28 +597,7 @@
type='result'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'/>
...
</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 <cite>XEP-0030</cite> information requests.</p>
<example caption="Service discovery information request"><![CDATA[
<iq from='romeo@montague.net/orchard'
id='disco3'
to='juliet@capulet.com/balcony'
type='get'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
]]></example>
<example caption="Service discovery information response"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='disco2'
to='romeo@montague.net/orchard'
type='result'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'/>
<feature var='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
...
</query>
</iq>
@ -644,31 +625,17 @@
<section2 topic='Protocol Namespaces' anchor='ns'>
<p>Until this specification advances to a status of Draft, its associated namespaces shall be:</p>
<ul>
<li>http://www.xmpp.org/extensions/xep-0176.html#ns-tcp</li>
<li>http://www.xmpp.org/extensions/xep-0176.html#ns-udp</li>
<li>http://www.xmpp.org/extensions/xep-0176.html#ns</li>
</ul>
<p>Upon advancement of this specification, the &REGISTRAR; shall issue permanent namespaces in accordance with the process defined in Section 4 of &xep0053;.</p>
<p>The following namespaces are requested, and are thought to be unique per the XMPP Registrar's requirements:</p>
<ul>
<li>urn:xmpp:jingle:transport:ice-tcp</li>
<li>urn:xmpp:jingle:transport:ice-udp</li>
</ul>
</section2>
<section2 topic='Jingle Transport Methods' anchor='registrar-transports'>
<p>The XMPP Registrar shall include "ice-tcp" and "ice-udp" in its registry of Jingle transport methods. The registry submission is as follows:</p>
<p>The XMPP Registrar shall include "ice-udp" in its registry of Jingle transport methods. The registry submission is as follows:</p>
<code><![CDATA[
<transport>
<name>ice-tcp</name>
<desc>
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>
@ -684,15 +651,14 @@
</section2>
</section1>
<section1 topic='XML Schemas' anchor='schema'>
<section2 topic='ICE-TCP Transport Method' anchor='schema-tcp'>
<code><![CDATA[
<section1 topic='XML Schema' anchor='schema'>
<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-tcp'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-tcp'
targetNamespace='http://www.xmpp.org/extensions/xep-0176.html#ns'
xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'
elementFormDefault='qualified'>
<xs:element name='transport'>
@ -741,65 +707,6 @@
</xs:simpleType>
</xs:schema>
]]></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>
]]></code>
</section1>
</xep>