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draft-ietf-sip-join and Semantics of REFER. Rohan Mahy rohan@cisco.com. Join Header Status. Join draft finished WGLC last week: ZERO comments — Does anyone care? No open issues Who’s read it? Who’s implemented it? Who’s planning to implement it?. Semantics of REFER.
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draft-ietf-sip-join andSemantics of REFER • Rohan Mahy • rohan@cisco.com
Join Header Status • Join draft finished WGLC last week: • ZERO comments — Does anyone care? • No open issues • Who’s read it? • Who’s implemented it? • Who’s planning to implement it?
Semantics of REFER • RFC 3515 says it is OK to put almost any arbitrary URI in a Refer-To header • arbitrary schemes • specific SIP methods • in or out of a dialog • preloaded SIP headers • What does that mean? • How do I authorize this?
What semantics make sense? Transfer Click to Dial Move Sub Remote Transfer Fetch content Send Busy • REFER in a dialog, Refer-To method=INVITE • REFER outside dialog, Refer-To method=INVITE • REFER with other methods: REGISTER, SUBSCRIBE, MESSSAGE • Nested REFERs • Refer-To: <http://> (targeted to dialog) • Refer-To: <http://> (not to a dialog) • Refer-To: <sip:user@foo.com;response=486>
How do you put REFER requests in a context? • Option 1: Send REFER on existing dialog • Option 2: Use a separate GRUU per conversation. (This gets cumbersome very fast. Requires lots of target refresh requests.) • Option 3: Use explicit Refer-To header parameters: • Refer-To: <http://foo.com/>;call-id=123 • ;remote-tag=abc;local-tag=xyz
How do we proceed? • Most uses of REFER other than transfer are unlikely to work on today’s UAs • Suggest that we define semantics of cohesive baskets of REFER functionality. Use option-tags to make sure these are supported. • Propose that we add the explicit dialog parameters to Refer-To header • Provide guidance: to what extent is remote call control, and remote UI invocation (app interaction) OK.