[Sip] content indirection design question
"Nasir Khan" <nkhan@bea.com> Fri, 24 February 2006 22:09 UTC
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From: Nasir Khan <nkhan@bea.com>
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Subject: [Sip] content indirection design question
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I have this question for the designers of http://www.ietf.org/internet-drafts/draft-ietf-sip-content-indirect-mech -05.txt The way the meta data about the indirect content is split between message and body is counter-intuitive. Eg. -----------------------------Actual------------------------- Content-Type: message/external-body; access-type="URL"; expiration="Mon, 24 June 2002 09:00:00 GMT"; URL=http://www.example.com/the-indirect-content Content-Length : 234 <CRLF> Content-Type: image/jpeg Content-Disposition: render --------------------------------- The Content-Type header indicates that this is an indirect content and also contains the pointer to the actual content, it contains a lot of other information about the content and then there is a Content-Length that is not the length of the actual content but the length of the content attributes that appear as Content headers in the body of this message, which contains some further information about the content. This type of semantic overloading and distribution has not been seen in most of the SIP design that I am aware of so far, what were the reasons for this design decision? You could have defined a simple protocol (which you have done indirectly) which is transported in the message body much like SDP and defines the content as indirect content, as an example .. Eg. ------------------------Suggested--------------------------------------- ---- Content-Type: application/indirect-content Content-Length: 563 <CRLF> Indirect-Content-Param: URL;expiration="Mon, 24 June 2002 09:00:00 GMT" Indirect-Content: http://www.example.com/the-indirect-content Indirect-Content-Type: image/jpeg Indirect-Content-Length : 234532 Indirect-Content-Description : Happy fish image ......etc etc. ------------------------------------------------------------------------ ---------- OR alternatively You could have extended SIP by adding these headers (Indirect-XXX) headers in this draft to describe the indirect content and left the body empty. Any of these approaches simplify the UA implementation, particularly in approach-1 that I describe above, I could have used a factory generated pluggable content protocol handler which is delegated to deal with the content it specializes in, selectable by Content-Type header alone which just reads the body of the message after <CRLF>, where it finds everything it needs. Thanks ~Nasir _______________________________________________________________________ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
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- [Sip] content indirection design question Nasir Khan
- Re: [Sip] content indirection design question Dean Willis
- RE: [Sip] content indirection design question Burger, Eric