RE: [Sip] Support for Multipart/MIME

["Christer Holmberg \(JO/LMF\)" <[e-mail]>]

Hi, 

>* if they're out of sync, which one takes precedence (that 
>is, do I process a Content-Type that isn't listed in the 
>Content-Type-List?)

The Content-Type contains "multipart/*", while the Content-Type-List
contains the types (app/sdp, app/isup, app/whatever etc) within that
multipart.

Please note that I am talking about SIP headers, not in the MIME bodies
(of course, if a MIME body contains another multipart/*, the header
could perhaps also be used there).

>* if a UA knew an intermediate box used Content-Type-List, 
>the UA could use Content-Type-List to make the intermediate 
>box think some sort of Content-Type is not present.  That 
>additional content-type might contain the secret of the 
>universe, which the intermediate box really needed to know.

Well, this depends on the functionality of the middle-box.

If the middle-box is going to do some kind of policing, or otherwise
verify that the multipart actually contains what is claimed in the
Content-Type-List, it will have to parse the multipart anyway.

>* looking for "^Content-Type *:" isn't too hard; you don't 
>really need to bother parsing MIME and looking for nested 
>parts unless there is, in fact, a content-type you care 
>about.  Per Paul's message, if you only want ones with
>Content-Disposition: session, you could look for that string 
>within 4-5 lines of Content-Type; if you found it, then you 
>could parse the MIME in the body.

I don't think it's that easy. Assume one MIME body contains a SIP
message (or part of a SIP message), or any other protocol which uses the
Content-Type header, which is not the Content-Type header of the MIME
body itself. The same goes for Content-Disposition.

Regards,

Christer




> > -----Original Message-----
> > From: Christer Holmberg (JO/LMF)
> > [mailto:[e-mail]]
> > Sent: Thursday, May 10, 2007 6:44 PM
> > To: Paul Kyzivat; Dan Wing
> > Cc: [e-mail]; [e-mail]
> > Subject: RE: [Sip] Support for Multipart/MIME
> > 
> > 
> > Hi,
> > 
> > The following is not a proposal, but more "brain storming".
> > 
> > Would it be helpful to have a SIP header, e.g. 
> > Content-Type-List, which
> > would list the different Content-Types in a multipart/* body. 
> > 
> > A node could then first check that header in order to see 
> whether the
> > multipart/* contains something a specific node is interested in - 
> > without having to parse the full multipart/* body first. It could 
> > speed up the processing in nodes which may have interest only in a 
> > small set of Content-Types.
> > 
> > Comments?
> > 
> > Regards,
> > 
> > Christer
> 


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