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Peter Saint-Andre 2007-11-21 18:11:22 +00:00
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xep-0167.xml
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@ -111,12 +111,12 @@
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>&xep0166; can be used to initiate and negotiate a wide range of peer-to-peer sessions. One session type of interest is audio chat. This document specifies a format for negotiating Jingle audio sessions over the Realtime Transport Protocol (RTP; see &rfc3550;).</p>
<p>&xep0166; can be used to initiate and negotiate a wide range of peer-to-peer sessions. One session type of interest is audio chat. This document specifies an application format for negotiating Jingle audio sessions, where the media is exchanged over the Realtime Transport Protocol (RTP; see &rfc3550;).</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
<p>The Jingle application format defined herein is designed to meet the following requirements:</p>
<ol>
<li>Enable negotiation of parameters necessary for audio chat over Realtime Transport Protocol (RTP; see &rfc3550;).</li>
<li>Enable negotiation of parameters necessary for audio chat over Realtime Transport Protocol (RTP).</li>
<li>Map these parameters to Session Description Protocol (SDP; see &rfc4566;) to enable interoperability.</li>
<li>Define informational messages related to audio chat (e.g., ringing, on hold, on mute).</li>
</ol>
@ -127,7 +127,7 @@
<li><p>The application format negotiation process is defined in the <link url='#negotiation'>Negotiating a Jingle Audio Session</link> section of this document.</p></li>
<li><p>The semantics of the &DESCRIPTION; element are defined in the <link url='#format'>Application Format</link> section of this document.</p></li>
<li><p>A mapping of Jingle semantics to the Session Description Protocol is provided in the <link url='#sdp'>Mapping to Session Description Protocol</link> section of this document.</p></li>
<li><p>A Jingle audio session SHOULD use a lossy transport method such as &xep0177; or the "ice-udp" method specified in &xep0176;, but MAY use a reliable transport such as "ice-tcp".</p></li>
<li><p>A Jingle audio session SHOULD use a lossy transport method such as &xep0177; or the "ice-udp" method specified in &xep0176;, but MAY use a reliable transport such as "ice-tcp" if a low-bandwidth codec is employed.</p></li>
<li>
<p>Content is to be sent and received as follows:</p>
<ul>
@ -138,9 +138,26 @@
</ol>
</section1>
<section1 topic='Application Format' anchor='format'>
<p>A Jingle audio session is described by a content type that contains one application format and one transport method. The application format consists of one or more encodings contained within a wrapper &lt;description/&gt; element qualified by the 'http://www.xmpp.org/extensions/xep-0167.html#ns' namespace &NSNOTE;. In the language of <cite>RFC 4566</cite> these encodings are payload-types; therefore, each &lt;payload-type/&gt; element specifies an encoding that can be used for the audio stream. In Jingle Audio, these encodings are used in the context of RTP. The most common encodings for the Audio/Video Profile (AVP) of RTP are listed in &rfc3551; (these "static" types are reserved from payload ID 0 through payload ID 95), although other encodings are allowed (these "dynamic" types use payload IDs 96 to 127) in accordance with the dynamic assignment rules described in Section 3 of <cite>RFC 3551</cite>.</p>
<p>The allowable attributes are as follows:</p>
<table caption='Defined Attributes'>
<p>A Jingle audio session is described by a content type that contains one application format and one transport method. The application format consists of one or more encodings contained within a wrapper &lt;description/&gt; element qualified by the 'http://www.xmpp.org/extensions/xep-0167.html#ns' namespace &NSNOTE;. In the language of <cite>RFC 4566</cite> each encoding is a payload-type; therefore, each &lt;payload-type/&gt; element specifies an encoding that can be used for the audio stream, as illustrated in the following example.</p>
<example caption="Audio description format"><![CDATA[
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
<payload-type id='96' name='speex' clockrate='16000'/>
<payload-type id='97' name='speex' clockrate='8000'/>
<payload-type id='18' name='G729'/>
<payload-type id='103' name='L16' clockrate='16000' channels='2'/>
<payload-type id='98' name='x-ISAC' clockrate='8000'/>
<payload-type id='102' name='iLBC'/>
<payload-type id='4' name='G723'/>
<payload-type id='0' name='PCMU' clockrate='16000'/>
<payload-type id='8' name='PCMA'/>
<payload-type id='13' name='CN'/>
</description>
]]></example>
<p>The &DESCRIPTION; element is intended to be a child of a &CONTENT; element as specified in <cite>XEP-0166</cite>.</p>
<p>The &CONTENT; element SHOULD possess a 'profile' attribute that specifies the exact protocol in use as would be encapsulated in SDP (e.g., "RTP/AVP" or "UDP/TLS/RTP/AVP").</p>
<p>The encodings SHOULD be provided in order of preference by placing the most-preferred &PAYLOADTYPE; element as the first child of the &DESCRIPTION; element (etc.).</p>
<p>The allowable attributes of the &PAYLOADTYPE; element are as follows:</p>
<table caption='Payload-Type Attributes'>
<tr>
<th>Attribute</th>
<th>Description</th>
@ -184,23 +201,7 @@
<td>OPTIONAL</td>
</tr>
</table>
<p>The encodings SHOULD be provided in order of preference.</p>
<example caption="Audio description format"><![CDATA[
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
<payload-type id='96' name='speex' clockrate='16000'/>
<payload-type id='97' name='speex' clockrate='8000'/>
<payload-type id='18' name='G729'/>
<payload-type id='103' name='L16' clockrate='16000' channels='2'/>
<payload-type id='98' name='x-ISAC' clockrate='8000'/>
<payload-type id='102' name='iLBC'/>
<payload-type id='4' name='G723'/>
<payload-type id='0' name='PCMU' clockrate='16000'/>
<payload-type id='8' name='PCMA'/>
<payload-type id='13' name='CN'/>
</description>
]]></example>
<p>The &DESCRIPTION; element is intended to be a child of a &JINGLE; element as specified in <cite>XEP-0166</cite>.</p>
<p>The encodings SHOULD be provided in order of preference by placing the most-preferred &PAYLOADTYPE; element as the first child of the &DESCRIPTION; element (etc.).</p>
<p>In Jingle Audio, the encodings are used in the context of RTP. The most common encodings for the Audio/Video Profile (AVP) of RTP are listed in &rfc3551; (these "static" types are reserved from payload ID 0 through payload ID 95), although other encodings are allowed (these "dynamic" types use payload IDs 96 to 127) in accordance with the dynamic assignment rules described in Section 3 of <cite>RFC 3551</cite>. The payload IDs are represented in the 'id' attribute.</p>
<p>Each &lt;payload-type/&gt; element MAY contain one or more child elements that specify particular parameters related to the payload. For example, as described in &rtpspeex;, the "cng", "mode", and "vbr" parameters may be specified in relation to usage of the Speex <note>See &lt;<link url='http://www.speex.org/'>http://www.speex.org/</link>&gt;.</note> codec. Where such parameters are encoded via the "fmtp" SDP attribute, they shall be represented in Jingle via the following format:</p>
<code><![CDATA[
<parameter name='foo' value='bar'/>
@ -208,11 +209,11 @@
<p>Note: The parameter names are effectively guaranteed to be unique, since &IANA; maintains a registry of SDP parameters (see &lt;<link url='http://www.iana.org/assignments/sdp-parameters'>http://www.iana.org/assignments/sdp-parameters</link>&gt;).</p>
</section1>
<section1 topic='Negotiating a Jingle Audio Session' anchor='negotiation'>
<p>When the initiator sends a session-initiate stanza to the receiver, the &DESCRIPTION; element includes all of the payload types that the initiator can receive for Jingle audio (each one encapsulated in a separate &PAYLOADTYPE; element):</p>
<p>When the initiator sends a session-initiate stanza to the responder, the &DESCRIPTION; element includes all of the payload types that the initiator can receive for Jingle audio (each one encapsulated in a separate &PAYLOADTYPE; element):</p>
<example caption="Initiation"><![CDATA[
<iq from='romeo@montague.net/orchard'
to='juliet@capulet.com/balcony'
id='jingleaudio1'
to='juliet@capulet.com/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'>
action='session-initiate'
@ -231,30 +232,30 @@
</jingle>
</iq>
]]></example>
<p>Upon receiving the session-initiate stanza, the receiver determines whether it can provisionally accept the session and proceed with the negotiation. The general Jingle error cases are specified in <cite>XEP-0166</cite> and illustrated in the <link url='#scenarios'>Scenarios</link> section of this document. In addition, the receiver must determine if it supports any of the payload types advertised by the initiator; if it supports none of the offered payload types, it must reject the session by returning a &notacceptable; error with a Jingle-Audio-specific condition of &lt;unsupported-codecs/&gt;:</p>
<example caption="Receiver does not support any of the codecs"><![CDATA[
<iq type='error'
from='juliet@capulet.com/balcony'
<p>Upon receiving the session-initiate stanza, the responder determines whether it can proceed with the negotiation. The general Jingle error cases are specified in <cite>XEP-0166</cite> and illustrated in the <link url='#scenarios'>Scenarios</link> section of this document. In addition, the responder must determine if it supports any of the payload types advertised by the initiator; if it supports none of the offered payload types, it must reject the session by returning a &notacceptable; error with a Jingle-Audio-specific condition of &lt;unsupported-codecs/&gt;:</p>
<example caption="Responder does not support any of the codecs"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='jingleaudio1'
to='romeo@montague.net/orchard'
id='jingleaudio1'>
type='error'>
<error type='cancel'>
<not-acceptable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<unsupported-codecs xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns-errors'/>
</error>
</iq>
]]></example>
<p>If there is no error, the receiver provisionally accepts the session:</p>
<example caption="Receiver provisionally accepts session"><![CDATA[
<p>If there is no error, the responder acknowledges the session-initiation request.</p>
<example caption="Responder acknowledges session-initiate"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='jingleaudio1'
to='romeo@montague.net/orchard'
type='result'/>
]]></example>
<p>The receiver then should send a list of the payload types that it can receive via a Jingle "content-accept" (or "session-accept") action. The list that the receiver sends MAY include any payload types (not a subset of the payload types sent by the initiator) but SHOULD retain the ID numbers specified by the initiator. The order of the &PAYLOADTYPE; elements indicates the receiver's preferences, with the most-preferred types first.</p>
<example caption="Receiver accepts content type"><![CDATA[
<p>The responder then should send a list of the payload types that it can receive via a Jingle "content-accept" (or "session-accept") action. The list that the responder sends MAY include any payload types (not a subset of the payload types sent by the initiator) but SHOULD retain the ID numbers specified by the initiator. The order of the &PAYLOADTYPE; elements indicates the responder's preferences, with the most-preferred types first.</p>
<example caption="Responder accepts content type"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='jingleaudio2'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'>
action='content-accept'
@ -278,20 +279,31 @@
<p>The initiator acknowledges the 'content-accept' with an empty IQ result:</p>
<example caption="Initiator acknowledges modified application format"><![CDATA[
<iq from='romeo@montegue.net/orchard'
to='juliet@capulet.com/balcony'
id='jingleaudio2'
to='juliet@capulet.com/balcony'
type='result'/>
]]></example>
<p>After successful transport negotiation (not shown here), the receiver then accepts the session:</p>
<example caption="Receiver definitively accepts the session"><![CDATA[
<iq type='set' from='juliet@capulet.com/balcony' to='romeo@montague.net/orchard' id='accept1'>
<p>After successful transport negotiation (not shown here), the responder then accepts the session:</p>
<example caption="Responder definitively accepts the session"><![CDATA[
<iq from='juliet@capulet.com/balcony'
id='accept1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-accept'
initiator='romeo@montague.net/orchard'
responder='juliet@capulet.com/balcony'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='RTP/AVP'>
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'/>
<description xmlns='http://www.xmpp.org/extensions/xep-0167.html#ns'>
<payload-type id='97' name='speex' clockrate='8000'/>
<payload-type id='18' name='G729'/>
<payload-type id='0' name='PCMU' />
<payload-type id='102' name='iLBC'/>
<payload-type id='4' name='G723'/>
<payload-type id='8' name='PCMA'/>
<payload-type id='13' name='CN'/>
</description>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns-udp'>
<candidate component='2'
foundation='1'
@ -310,17 +322,17 @@
</iq>
]]></example>
<p>And the initiator acknowledges session acceptance:</p>
<example caption="initiator acknowledges session acceptance"><![CDATA[
<example caption="Initiator acknowledges session acceptance"><![CDATA[
<iq from='romeo@montague.net/orchard'
to='juliet@capulet.com/balcony'
id='accept1'
to='juliet@capulet.com/balcony'
type='result'/>
]]></example>
<p>Note: Because a "session-accept" action implicitly indicates acceptance of the application format (i.e., "content-accept"), it is not necessary to send a separate "content-accept" action. This flow is shown for completeness only.</p>
</section1>
<section1 topic='Scenarios' anchor='scenarios'>
<p>The following sections show a number of Jingle audio scenarios, in relative order of complexity.</p>
<section2 topic='Receiver is Busy' anchor='scenarios-busy'>
<section2 topic='Responder is Busy' anchor='scenarios-busy'>
<p>In this scenario, Romeo initiates a voice chat with Juliet but she is otherwise engaged.</p>
<p>The session flow is as follows:</p>
<code><![CDATA[
@ -352,9 +364,9 @@ Romeo Juliet
</jingle>
</iq>
]]></example>
<example caption="Receiver returns recipient-unavailable error"><![CDATA[
<example caption="Responder returns recipient-unavailable error"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
id='jingle1'
to='romeo@montague.lit/orchard'
type='error'>
<error type='wait'>
@ -413,16 +425,16 @@ Romeo Juliet
</jingle>
</iq>
]]></example>
<example caption="Receiver sends provisional acceptance"><![CDATA[
<example caption="Responder sends provisional acceptance"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<example caption="Receiver sends ringing message"><![CDATA[
<example caption="Responder sends ringing message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='ringing1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -521,17 +533,29 @@ Romeo Juliet
]]></example>
<p>For each candidate received, the other party acknowledges receipt or returns an error:</p>
<example caption="Responder acknowledges receipt"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='info1' type='result'/>
<iq from='juliet@capulet.lit/balcony'
id='info1'
to='romeo@montague.lit/orchard'
type='result'/>
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='info2' type='result'/>
<iq from='juliet@capulet.lit/balcony'
id='info2'
to='romeo@montague.lit/orchard'
type='result'/>
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='info3' type='result'/>
<iq from='juliet@capulet.lit/balcony'
id='info3'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>At the same time (i.e., immediately after provisionally accepting the session, not waiting for the initiator to begin or finish sending candidates), the responder also begins sending candidates that may work for it. As above, the initiator acknowledges receipt of the candidates.</p>
<p>At the same time (i.e., immediately after acknowledging the session-initation request, not waiting for the initiator to begin or finish sending candidates), the responder also begins sending candidates that may work for it. As above, the initiator acknowledges receipt of the candidates.</p>
<p>As the initiator and responder receive candidates, they probe the various candidate transports for connectivity. In performing these connectivity checks, the parties follow the procedure specified in Section 7 of <cite>draft-ietf-mmusic-ice</cite>.</p>
<p>If one of the candidate transports is found to work, the receiver accepts the session.</p>
<example caption="Receiver sends session-accept"><![CDATA[
<iq type='set' from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='accept1'>
<p>If one of the candidate transports is found to work, the responder accepts the session.</p>
<example caption="Responder sends session-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-accept'
initiator='romeo@montague.lit/orchard'
@ -556,12 +580,15 @@ Romeo Juliet
]]></example>
<p>If the payload types and transport candidate can be successfully used by both parties, then the initiator acknowledges the session-accept.</p>
<example caption="Initiator acknowledges session-accept"><![CDATA[
<iq type='result' to='juliet@capulet.lit/balcony' from='romeo@montague.lit/orchard' id='accept1'/>
<iq from='romeo@montague.lit/orchard'
id='accept1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<p>The parties now begin to exchange media. In this case they would exchange audio using the Speex codec at a clockrate of 8000 since that is the highest-priority codec for the responder (as determined by the XML order of the &PAYLOADTYPE; children).</p>
<p>The parties may continue the session as long as desired.</p>
<p>Eventually, one of the parties terminates the session.</p>
<example caption="Receiver terminates the session"><![CDATA[
<example caption="Responder terminates the session"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='term1'
to='romeo@montague.lit/orchard'
@ -582,7 +609,7 @@ Romeo Juliet
]]></example>
</section2>
<section2 topic='Jingle Audio and Video via RTP/AVP, Negotiated with ICE-UDP' anchor='scenarios-voicechat'>
<p>In this scenario, Romeo initiates a combined audio and video chat with Juliet using a transport method of ICE. Juliet at first refuses the video portion, then later offers to add video, which Romeo accepts. The parties also exchange various informational messages</p>
<p>In this scenario, Romeo initiates a combined audio and video chat with Juliet using a transport method of ICE-UDP. Juliet at first refuses the video portion, then later offers to add video, which Romeo accepts. The parties also exchange various informational messages</p>
<p>The session flow is as follows:</p>
<code><![CDATA[
Romeo Juliet
@ -638,7 +665,10 @@ Romeo Juliet
]]></code>
<p>The protocol flow is as follows.</p>
<example caption="Initiation"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='jingle1' type='set'>
<iq from='romeo@montague.lit/orchard'
id='jingle1'
to='juliet@capulet.lit/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-initiate'
initiator='romeo@montague.lit/orchard'
@ -669,13 +699,16 @@ Romeo Juliet
</jingle>
</iq>
]]></example>
<example caption="Receiver acknowledges receipt of initiation request"><![CDATA[
<iq type='result' from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='jingle1'/>
<example caption="Responder acknowledges session-initiate request"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='jingle1'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<example caption="Receiver sends ringing message"><![CDATA[
<example caption="Responder sends ringing message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='ringing1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -692,8 +725,11 @@ Romeo Juliet
type='result'/>
]]></example>
<p>However, Juliet doesn't want to do video because she is having a bad hair day, so she sends a "content-remove" request to Romeo.</p>
<example caption="Receiver requests content-remove"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='remove1' type='set'>
<example caption="Responder requests content-remove"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='remove1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-remove'
initiator='romeo@montague.lit/orchard'
@ -704,29 +740,38 @@ Romeo Juliet
]]></example>
<p>Romeo then acknowledges the content-remove request and, if it is acceptable, returns a content-accept:</p>
<example caption="Initiator acknowledges content-remove"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='remove1' type='result'/>
<iq from='romeo@montague.lit/orchard'
id='remove1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<example caption="Initiator accepts content definition"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='remove2' type='set'>
<iq from='romeo@montague.lit/orchard'
id='remove2'
to='juliet@capulet.lit/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept'
initiator='romeo@montague.lit/orchard'
sid='a73sjjvkla37jfea'>
<content creator='responder' name='this-is-the-video-content' profile='RTP/AVP'>
<description xmlns='http://www.xmpp.org/extensions/xep-0180.html#ns'/>
<transport xmlns='http://www.xmpp.org/extensions/xep-0176.html#ns'/>
</content>
<content creator='responder' name='this-is-the-audio-content' profile='RTP/AVP'/>
</jingle>
</iq>
]]></example>
<p>The other party then acknowledges the acceptance.</p>
<example caption="Receiver acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='remove2' type='result'/>
<example caption="Responder acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='remove2'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>As in the previous scenario, the parties exchange ICE candidates (see above for examples).</p>
<p>Once the parties find candidate transports that work, the receiver accepts the session.</p>
<example caption="Receiver sends session-accept"><![CDATA[
<iq type='set' from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='accept1'>
<p>Once the parties find candidate transports that work, the responder accepts the session.</p>
<example caption="Responder sends session-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-accept'
initiator='romeo@montague.lit/orchard'
@ -751,14 +796,17 @@ Romeo Juliet
]]></example>
<p>As above, if the payload types and transport candidate can be successfully used by both parties, then the initiator acknowledges the session-accept.</p>
<example caption="Initiator acknowledges session-accept"><![CDATA[
<iq type='result' to='juliet@capulet.lit/balcony' from='romeo@montague.lit/orchard' id='accept1'/>
<iq from='romeo@montague.lit/orchard'
id='accept1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<p>The parties now begin to exchange media. In this case they would exchange audio using the Speex codec at a clockrate of 8000 since that is the highest-priority codec for the responder (as determined by the XML order of the &PAYLOADTYPE; children).</p>
<p>Juliet wants to get her hair in order so she puts Romeo on hold.</p>
<example caption="Receiver sends hold message"><![CDATA[
<p>The parties chat for a while. Eventually Juliet wants to get her hair in order so she puts Romeo on hold.</p>
<example caption="Responder sends hold message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='hold1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -775,10 +823,10 @@ Romeo Juliet
type='result'/>
]]></example>
<p>Juliet returns so she informs Romeo that she is actively engaged in the call again.</p>
<example caption="Receiver sends active message"><![CDATA[
<example caption="Responder sends active message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='active1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -796,8 +844,11 @@ Romeo Juliet
]]></example>
<p>The parties now continue the audio chat.</p>
<p>Finally Juliet decides that she is presentable for a video chat so she sends a content-add request to Romeo.</p>
<example caption="Receiver sends a content-add"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='add1' type='set'>
<example caption="Responder sends a content-add"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='add1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-add'
initiator='romeo@montague.lit/orchard'
@ -819,10 +870,16 @@ Romeo Juliet
]]></example>
<p>The entity receiving the content-add request then acknowledges the request and, if it is acceptable, returns a content-accept:</p>
<example caption="Initiator acknowledges content-add"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='add1' type='result'/>
<iq from='romeo@montague.lit/orchard'
id='add1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<example caption="Initiator accepts content type definition"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='add2' type='set'>
<iq from='romeo@montague.lit/orchard'
id='add2'
to='juliet@capulet.lit/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept'
initiator='romeo@montague.lit/orchard'
@ -843,8 +900,11 @@ Romeo Juliet
</iq>
]]></example>
<p>The other party then acknowledges the acceptance.</p>
<example caption="Receiver acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='add2' type='result'/>
<example caption="Responder acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='add2'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>The media session proceeds. Now they would exchange both audio and video, where the audio is exchanged the Speex codec at a clockrate of 8000 and the video is exchanged using the Theora codec with a height of 720 pixels, a width of 1280 pixels, and so on.</p>
<p>The parties may continue the session as long as desired.</p>
@ -861,7 +921,7 @@ Romeo Juliet
sid='a73sjjvkla37jfea'/>
</iq>
]]></example>
<example caption="Receiver acknowledges session-terminate"><![CDATA[
<example caption="Responder acknowledges session-terminate"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='term1'
to='romeo@montague.lit/orchard'
@ -907,7 +967,10 @@ Romeo Juliet
]]></code>
<p>The protocol flow is as follows.</p>
<example caption="Initiator sends session-initiate"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='jingle1' type='set'>
<iq from='romeo@montague.lit/orchard'
id='jingle1'
to='juliet@capulet.lit/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-initiate'
initiator='romeo@montague.lit/orchard'
@ -925,16 +988,16 @@ Romeo Juliet
</jingle>
</iq>
]]></example>
<example caption="Receiver sends provisional acceptance"><![CDATA[
<example caption="Responder acknowledges session-initiate"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
id='jingle1'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<example caption="Receiver sends ringing message"><![CDATA[
<example caption="Responder sends ringing message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='ringing1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -951,22 +1014,33 @@ Romeo Juliet
type='result'/>
]]></example>
<p>However, Juliet wants to make sure that the communications are encrypted, so she sends a "content-modify" request to Romeo.</p>
<example caption="Receiver requests content-modify"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='mod1' type='set'>
<example caption="Responder requests content-modify"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='mod1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-modify'
initiator='romeo@montague.lit/orchard'
sid='a73sjjvkla37jfea'>
<content creator='initiator' name='this-is-the-audio-content' profile='UDP/TLS/RTP/AVP'/>
<content creator='responder'
name='this-is-the-audio-content'
profile='UDP/TLS/RTP/AVP'/>
</jingle>
</iq>
]]></example>
<p>Romeo then acknowledges the content-modify request and, if it is acceptable, returns a content-accept:</p>
<example caption="Initiator acknowledges content-modify"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='mod1' type='result'/>
<iq from='romeo@montague.lit/orchard'
id='mod1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<example caption="Initiator accepts content definition"><![CDATA[
<iq from='romeo@montague.lit/orchard' to='juliet@capulet.lit/balcony' id='mod2' type='set'>
<iq from='romeo@montague.lit/orchard'
id='mod2'
to='juliet@capulet.lit/balcony'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='content-accept'
initiator='romeo@montague.lit/orchard'
@ -976,13 +1050,19 @@ Romeo Juliet
</iq>
]]></example>
<p>The other party then acknowledges the acceptance.</p>
<example caption="Receiver acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='mod2' type='result'/>
<example caption="Responder acknowledges content-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='mod2'
to='romeo@montague.lit/orchard'
type='result'/>
]]></example>
<p>As in the previous scenario, the parties exchange ICE candidates (see above for examples).</p>
<p>If one of the candidate transports is found to work, the receiver accepts the session.</p>
<example caption="Receiver sends session-accept"><![CDATA[
<iq type='set' from='juliet@capulet.lit/balcony' to='romeo@montague.lit/orchard' id='accept1'>
<p>If one of the candidate transports is found to work, the responder accepts the session.</p>
<example caption="Responder sends session-accept"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='accept1'
to='romeo@montague.lit/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-accept'
initiator='romeo@montague.lit/orchard'
@ -1007,12 +1087,15 @@ Romeo Juliet
]]></example>
<p>If the payload types and transport candidate can be successfully used by both parties, then the initiator acknowledges the session-accept.</p>
<example caption="Initiator acknowledges session-accept"><![CDATA[
<iq type='result' to='juliet@capulet.lit/balcony' from='romeo@montague.lit/orchard' id='accept1'/>
<iq from='romeo@montague.lit/orchard'
id='accept1'
to='juliet@capulet.lit/balcony'
type='result'/>
]]></example>
<p>The parties now begin to exchange media. In this case they would exchange audio using the Speex codec at a clockrate of 8000 since that is the highest-priority codec for the responder (as determined by the XML order of the &PAYLOADTYPE; children).</p>
<p>The parties may continue the session as long as desired.</p>
<p>Eventually, one of the parties terminates the session.</p>
<example caption="Receiver terminates the session"><![CDATA[
<example caption="Responder terminates the session"><![CDATA[
<iq from='juliet@capulet.lit/balcony'
id='term1'
to='romeo@montague.lit/orchard'
@ -1039,7 +1122,7 @@ Romeo Juliet
<code><![CDATA[
m=<media> <port> <transport> <fmt list>
]]></code>
<p>In the context of Jingle audio sessions, the &lt;media&gt; is "audio", the &lt;port&gt; is the preferred port for such communications (which may be determined dynamically), the &lt;transport&gt; is whatever profile is negotiated via the 'profile' attribute of the &CONTENT; element in the Jingle negotiation (e.g., "RTP/AVT"), and the &lt;fmt list&gt; is the payload-type ID.</p>
<p>In the context of Jingle audio sessions, the &lt;media&gt; is "audio", the &lt;port&gt; is the preferred port for such communications (which may be determined dynamically), the &lt;transport&gt; is whatever profile is negotiated via the 'profile' attribute of the &CONTENT; element in the Jingle negotiation (e.g., "RTP/AVP"), and the &lt;fmt list&gt; is the payload-type ID.</p>
<p>For example, consider the following static payload-type:</p>
<example caption="Jingle format for static payload-type"><![CDATA[
<payload-type id="13" name="CN"/>
@ -1056,7 +1139,7 @@ m=audio 9999 RTP/AVP 13
m=audio 9999 RTP/AVP 96
a=rtpmap:96 speex/16000
]]></example>
<p>As noted, if additional parameters are to be specified, they shall be represented as attributes of the &lt;payload-type/&gt; element of the child &lt;parameter/&gt; element, as in the following example.</p>
<p>As noted, if additional parameters are to be specified, they shall be represented as attributes of the &lt;parameter/&gt; child of the &PAYLOADTYPE; element, as in the following example.</p>
<example caption="Jingle format for dynamic payload-type with parameters"><![CDATA[
<payload-type id='96' name='speex' clockrate='16000' ptime='40'>
<parameter name='vbr' value='on'/>
@ -1098,10 +1181,10 @@ a=fmtp:96 vbr=on;cng=on
<p>Note: Because the informational message is sent in an IQ-set, the receiving party MUST return either an IQ-result or an IQ-error (normally only an IQ-result to acknowledge receipt; no error flows are defined or envisioned at this time).</p>
</section2>
<section2 topic='Examples' anchor='info-examples'>
<example caption="Receiver sends active message"><![CDATA[
<example caption="Responder sends active message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='active1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'>
action='session-info'
@ -1111,10 +1194,10 @@ a=fmtp:96 vbr=on;cng=on
</jingle>
</iq>
]]></example>
<example caption="Receiver sends hold message"><![CDATA[
<example caption="Responder sends hold message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='hold1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -1124,10 +1207,10 @@ a=fmtp:96 vbr=on;cng=on
</jingle>
</iq>
]]></example>
<example caption="Receiver sends mute message"><![CDATA[
<example caption="Responder sends mute message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='mute1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -1137,10 +1220,10 @@ a=fmtp:96 vbr=on;cng=on
</jingle>
</iq>
]]></example>
<example caption="Receiver sends ringing message"><![CDATA[
<example caption="Responder sends ringing message"><![CDATA[
<iq from='juliet@capulet.com/balcony'
to='romeo@montague.net/orchard'
id='ringing1'
to='romeo@montague.net/orchard'
type='set'>
<jingle xmlns='http://www.xmpp.org/extensions/xep-0166.html#ns'
action='session-info'
@ -1155,7 +1238,7 @@ a=fmtp:96 vbr=on;cng=on
<section1 topic='Error Handling' anchor='errors'>
<p>The Jingle-Audio-specific error conditions are as follows:</p>
<table caption='Other Error Conditions'>
<table caption='Error Conditions'>
<tr>
<th>Jingle Audio Condition</th>
<th>XMPP Condition</th>
@ -1192,6 +1275,7 @@ a=fmtp:96 vbr=on;cng=on
</query>
</iq>
]]></example>
<p>Naturally, support may also be discovered by the dynamic, presence-based profile of service discovery defined in &xep0115;.</p>
</section1>
<section1 topic='Implementation Notes' anchor='impl'>
@ -1202,12 +1286,12 @@ a=fmtp:96 vbr=on;cng=on
<p>If it is necessary to send Dual Tone Multi-Frequency (DTMF) tones, it is REQUIRED to use the XML format specified &xep0181;.</p>
</section2>
<section2 topic='When to Listen' anchor='impl-listen'>
<p>When the Jingle Audio content is accepted via a 'content-accept' action, both initiator and responder SHOULD start listening for audio as defined by the negotiated transport method and audio application format. For interoperability with telephony systems, each entity SHOULD both play any audio received and send a ringing tone at this time (i.e., before the receiver sends a 'session-accept' action).</p>
<p>When the Jingle Audio content type is accepted via a "content-accept" action, both initiator and responder SHOULD start listening for audio as defined by the negotiated transport method and audio application format. For interoperability with telephony systems, after the responder acknowledges the session-initiate request, the responder SHOULD send a "ringing" message and both parties SHOULD play any audio received.</p>
</section2>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>In order to secure the data stream, implementations SHOULD use encryption methods appropriate to the transport method and media being exchanged; for example, in the case of UDP, that would include Datagram Transport Layer Security (DTLS) as specified in &rfc4347;. <cite>draft-fishl-mmusic-sdp-dtls</cite> defines such methods for the Session Description Protocol; the relevant RTP profile (e.g., "UDP/TLS/RTP/AVP" for transporting the RTP stream over DTLS with UDP) shall be specified as the value of the &CONTENT; element's 'profile' attribute.</p>
<p>In order to secure the data stream, implementations SHOULD use encryption methods appropriate to the transport method and media being exchanged; for example, in the case of UDP, that would include Datagram Transport Layer Security (DTLS) as specified in &rfc4347;. The work-in-progress <cite>draft-fishl-mmusic-sdp-dtls</cite> defines such methods for the Session Description Protocol; the relevant RTP profile (e.g., "UDP/TLS/RTP/AVP" for transporting the RTP stream over DTLS with UDP) shall be specified as the value of the &CONTENT; element's 'profile' attribute.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
@ -1252,8 +1336,9 @@ a=fmtp:96 vbr=on;cng=on
<xs:element name='payload-type'>
<xs:complexType>
<xs:sequence minOccurs='0' maxOccurs='unbounded'> <xs:element ref='parameter'/>
</xs:choice>
<xs:sequence minOccurs='0' maxOccurs='unbounded'>
<xs:element ref='parameter'/>
</xs:sequence>
<xs:attribute name='channels' type='xs:byte' use='optional' default='1'/>
<xs:attribute name='clockrate' type='xs:short' use='optional'/>
<xs:attribute name='id' type='xs:unsignedByte' use='required'/>