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DesignXMPP conference » History » Version 11

Saúl Ibarra Corretgé, 01/29/2013 10:29 PM

1 2 Adrian Georgescu 
h1. SIP-XMPP Multiparty Chat
2 3 Adrian Georgescu 





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This is done by bridging MUC functionality from XMPP with MSRP-Switch functionality using SIP.





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  * SIP users can create ad-hoc conference rooms using SylkServer MSRP chat and invite users from both SIP and XMPP domains





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 * XMPP users can create multiparty conferences using SylkServer MUC capability and invite users from both XMPP and SIP worlds





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    Saúl  Ibarra Corretgé
    





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h2. Joining a conference





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A conference room will be created if it doesn't exist previously. For joining a conference, an XMPP endpoint will send a presence stanza with the URI of the room. SylkServer handles conferences as part of the conference application, so it will create a new SIP session which will join the conference.Usually the SIP INVITE will loop in the proxy and enter SylkServer again, but this time the executed application will be "conference".





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    Saúl  Ibarra Corretgé
    
The XMPP gateway application will receive SIP NOTIFY requests with "RFC 4575":https://tools.ietf.org/html/rfc4575 payload specifying the participants in the room, and this will be translated into presence stanza elements. Likewise, all MSRP messages received on the SIP session will be translated into _groupchat_ message stanzas.





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!{ 700px, center}xmppgw_muc_x2s.png!





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h2. Inviting new participants





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    Saúl  Ibarra Corretgé
    
SylkServer allows for XMPP users to invite SIP endpoints or vice versa. This is accomplished in the same fashion as joining a conference: it takes place on the _conference_ application, which is based on SIP. Here is the sequence of actions which are performed for inviting a SIP or XMPP endpoint to a conference room, from an XMPP endpoints standpoint:





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# A message stanza with the _invite_ element pointing to the desired user





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# SylkServer sends a out of dialog REFER request towards the conference room URI and indicates the use that needs to be invited in a Refer-To header





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# When the REFER request arrives back at SylkServer, it will create an outgoing SIP session towards the URI in the Refer-To header, it also indicates that the session comes from a conference server by adding the _isfocus_ contact header parameter





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# If the invited user was a SIP endpoint, it will accept the session and join the conference





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# If the invited user was a XMPP endpoint, the SIP INVITE will enter SylkServer yet again, but this time it will be handled by the XMPP gateway application





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# The XMPP gateway application detects the INVITE as an invitation to join a conference because it contains a Referred-By header and the _isfocus_ contact header parameter





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# SylkServer sends a message stanza to the invited user indicating who invited him





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