<p>In order to initiate a Jingle session, the initiator must determine which of the responder's XMPP resources is best for the desired application format. Methods for doing so are out of scope for this specification. However, see the <linkurl='#support'>Determining Support</link> section of this document (and associated specifications) for relevant information.</p>
<p>Once the initiator has discovered which of the responder's XMPP resources is ideal for the desired application format, it sends a session initiation request to the responder. This request is an IQ-set containing a &JINGLE; element qualified by the 'http://www.xmpp.org/extensions/xep-0166.html#ns' namespace &NSNOTE;, where the value of the 'action' attribute is "session-initiate" and where the &JINGLE; element contains one or more &CONTENT; elements. Each &CONTENT; element defines a content type to be transferred during the session, and each &CONTENT; element in turn contains one &DESCRIPTION; child element that specifies a desired application format and one &TRANSPORT; child element that specifies a potential transport method. If either party wishes to propose the use of multiple transport methods for the same application format, it must send multiple &CONTENT; elements.</p>
<p>Once the initiator has discovered which of the responder's XMPP resources is ideal for the desired application format, it sends a session initiation request to the responder. This request is an IQ-set containing a &JINGLE; element qualified by the 'urn:xmpp:tmp:jingle' namespace &NSNOTE;, where the value of the 'action' attribute is "session-initiate" and where the &JINGLE; element contains one or more &CONTENT; elements. Each &CONTENT; element defines a content type to be transferred during the session, and each &CONTENT; element in turn contains one &DESCRIPTION; child element that specifies a desired application format and one &TRANSPORT; child element that specifies a potential transport method. If either party wishes to propose the use of multiple transport methods for the same application format, it must send multiple &CONTENT; elements.</p>
<p>Note: The syntax and semantics of the &DESCRIPTION; and &TRANSPORT; elements are out of scope for this specification, since they are defined in related specifications. The syntax and semantics of the &JINGLE; and &CONTENT; elements are specified in this document under <linkurl='#def'>Formal Definition</link>.</p>
<p>Note: In order to expedite session establishment, the initiator MAY send transport candidates (e.g., for negotiation of the ICE transport) immediately after sending the "session-initiate" message and before receiving acknowledgement from the responder (i.e., the initiator MUST consider the session to be PENDING 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 <unknown-session/> errors since according to its state machine the session does not exist).</p>
<p>Another reason for terminating the session is that the terminating party already has an existing session with the other party and wishes to use that session rather than initiate a new session; in this case, the recommended reasoncode is "alternative-session" and the terminating party should include the session ID of the atlernative session in the 'reasontext' attribute.</p>
<examplecaption="Terminating the session (existing session)"><![CDATA[
<iqfrom='juliet@capulet.lit/balcony'
id='term1'
to='romeo@montague.lit/orchard'
type='set'>
<jinglexmlns='urn:xmpp:tmp:jingle'
action='session-terminate'
initiator='romeo@montague.lit/orchard'
reasoncode='alternative-session'
reasontext='b84tkkwlmb48kgfb'/>
sid='a73sjjvkla37jfea'/>
</iq>
]]></example>
<p>Another reason for terminating the session is that the terminating party does not support any of the offered application formats; in this case, the recommended reasoncode is "unsupported-applications".</p>
<p>The Jingle-specific error conditions are as follows. These condition elements are qualified by the 'http://www.xmpp.org/extensions/xep-0166.html#ns-errors' namespace &NSNOTE;.</p>
<p>The Jingle-specific error conditions are as follows. These condition elements are qualified by the 'urn:xmpp:tmp:jingle-errors' namespace &NSNOTE;.</p>
<p>If an entity supports Jingle, it MUST advertise that fact by returning a feature of "http://www.xmpp.org/extensions/xep-0166.html#ns" &NSNOTE; in response to a &xep0030; information request. The response MUST also include features for the application formats and transport methods supported by the responding entity, as described in the relevant specifications.</p>
<p>If an entity supports Jingle, it MUST advertise that fact by returning a feature of "urn:xmpp:tmp:jingle" &NSNOTE; in response to a &xep0030; information request. The response MUST also include features for the application formats and transport methods supported by the responding entity, as described in the relevant specifications.</p>
<examplecaption="Service Discovery Information Request"><
Peter Saint-Andre
16 years ago