Hi, 

>>So, something like "Content-Type: application/info+foo" would solve 
>>this. No need for new headers, no need for CIDs, no need for
nothing...
>>That is MY definition of KISS (apart from being one of the coolest 
>>rock band :)
>
>For one thing, we don't need to change ANY C-* in the INFO message and
still get what we want - if that's not "simple" then I don't know what
is.  :)
>
>It is also debatable that having a solution for a specific message type
and then a different solution for other message types is "simple"; or
even having a body "type" that is unique for each message 
>type vs. generic to all is "simple".  It may be simpler for the first
message type you do it to, but then you have to reproduce that code for
all message types anyway.

If we have a package specific C-T value we probably don't even need the
Info-Package header. So, absolutely no reason to link a header with a
body part, because there is no header. Just like SDP.

We use Send-Info to negotiate that we support foo, and then I send you
foo with C-T: application/info+foo. Very simple.

If people then want to define some generic SIP mechanism for some
problem I am not sure we all agree what it is, fine. If needed, you can
then use that solution also for your info package body parts.

>>Because, in most cases today clients are able to find out what is in a
message body, and what to do with it, based on the Content-Type value.
>
>No, that may be what some of them do in code, or what it appears like
they're doing from a wireshark trace, but what 3261 says is that in fact
there is a C-D that extends the C-T.  It just happens to be 
>that "session" is the implicit C-D for "application/sdp", and "render"
is the implicit C-D for everything else.  So as far as we know they're
actually doing it right.

In my experience, the problem is not "context", because it is know what
information is sent in what message. In addition, C-T (together with C-D
if you like) tells you what a body part contains, so you can process and
parse the message. There is no need to link any CIDs between SIP headers
and body parts in order to figure out what to do.

So, by using C-T for info packages it will work ecactly the same way for
INFO. I look at C-T, and I process and parse the info package body part.
Simple.

>BTW, it's not that I disagree with you that content-types to date have
been unambiguous in reality.  They have, afaik.  And I think we would be
well-advised to keep future extensions from re-using 
>already defined C-T's if ambiguity could occur.  For most things we're
pretty safe.  For example, any future Info package would be safe to
re-use existing C-T's, because a negotiation mechanism is in 
>place to indicate package support, so you wouldn't get a message with
the package to begin with if you didn't understand it and support
disambiguating body parts.

I just think it is very useful and simple to able to look at the C-T
value in order to figure out what is in the body part...

Regards,

Christer

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