Subject: [Sip] The Five Meanings of the REFER Method

From: "Dale R. Worley" <[email-masked]>
Date: Sun, 18 Jun 2006 20:34:05 -0400

Now that the deadline is upon me, I've written up my catalog of the
different uses of the REFER method, draft-worley-sip-many-refers-00,
"The Five Meanings of the REFER Method".  Until it shows up in the I-D
directories, you can fetch it from:

http://scm.sipfoundry.org/rep/ietf-drafts/worley/draft-worley-sip-many-
refers-00.{txt,html,xml}

   The REFER method is defined in RFC 3515.  That RFC defines the syntax
   of the REFER request and some of the machinery involved in its
   execution, but it defines the semantics of the method only so far as
   to specify that the recipient will initiate a request to the target
   specified in the Refer-To header.  But since almost all requests that
   can be sent by the recipient are inherently part of an encompassing
   UA action that affects the state of the recipient in ways that are
   not directly reflected in SIP protocol actions, the standardized
   action of initiating a request implicitly has further consequences
   which are often not clearly specified.  As a result, various SIP
   call-control proposals assume that a UA receiving a REFER will
   perform the UA operation that is needed at that moment without
   specifying clearly how the UA recognizes which UA operation is
   needed.  As a result there are now five semantically distinct defined
   uses of REFER.  All five uses bear a family resemblance, and each
   involves sending a SIP request, but the exact meaning of each use is
   logically independent of the others, and the rules by which a UA
   distinguishes the five cases are at best implicit.

Dale

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip