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Re: [Sip] Multiple body-parts in one INFO



Christer Holmberg wrote:

Hi,

Most of the multipart cases I've seen have worked fine, because the
Content-Type normally tells everything the receiver needs to know (e.g.
SDP, ISUP, XML-whatever, etc).

I guess the potential problem is when you send things like image/jpeg
etc.
The scary part is that demuxing based on C-T *does* work in a lot of simple cases, so it may be used widely. But it doesn't work in general. To work generally, it will be necessary to first demux based on C-D.
If we have a lot of implementations basing things on C-T, then they may not be inserting, or doing the necessary processing for C-D. That means they are likely to break in more complex cases going forward. 


For info packages, I still don't understand why we can't specify a
common content-type value. The body part contains an info package, so
the content-typ is info something.
If you chose a standard C-T for all info-packages, that constrains the syntax that it may contain. Yet each package is going to want to choose the syntax(es) that it uses. And some of them will want to be standard ones, such as image/jpeg. To deal with that your "standard" info C-T would have to be a container for an arbitrary mime type. So you have simply pushed the problem down a level. 


That way we would solve the how-to-find-info-body-parts problem, and
whatever common stuff then needs to be done for SIP can be done outside
the work of info.


IMO its a really bad way to go.

	Thanks,
	Paul


Regards,
Christer 
-----Original Message-----
From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On Behalf Of Hadriel Kaplan 
Sent: 3. joulukuuta 2008 0:42
To: Dean Willis
Cc: SIP List
Subject: Re: [Sip] Multiple body-parts in one INFO




-----Original Message-----
From: Dean Willis [mailto:dean.willis at softarmor.com]
Sent: Tuesday, December 02, 2008 4:07 PM
Seriously - you expect us to put in a Require header
option-tag when
multi-part mime is used, so it can fail against every SIP device that is deployed on the planet??
If understanding how to decode the multipart MIME is
critical to the
success of the request, then I expect the request to fail
if the UAS
cannot decode it. Further, I want it to fail predictably in
a way that
the request originator can understand, not in some cryptic application/version dependent way.
What you are suggesting is that to use multi-part MIME in current SIP methods, we cannot rely on currently deployed system behavior. So you're basically proposing we either: 
1) Never do multi-part MIME.
2) Do a new SIP version.
I'm ok with doing #1, but I don't think things are *that* bad anyway. I think we can rely on systems to behave sanely enough to do a backwards-compatible multi-part that should work in most cases - for the cases it doesn't, I think it will fail explicitly (with a failure response), and *then* one can argue if you can re-send it without the other body parts, or if you just fail the call hard. But at least by then you've actually hit an error, and it's not ALL deployed systems that will have the problem.
Although I do wonder about how much of a Red Herring this topic is - what exact use-cases do you guys have for multi-part bodies in SUBSCRIBE, NOTIFY, PUBLISH, and INFO that is not actually defined in a package for them? Or are we in some theoretical La-La land? [no offense meant - I like La-La land] 

-hadriel
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_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sipping at ietf.org for new developments on the application of sip


_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sipping at ietf.org for new developments on the application of sip