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

[Hadriel Kaplan <HKaplan at acmepacket.com>]

> -----Original Message-----
> From: Christer Holmberg [mailto:christer.holmberg at ericsson.com]
> Sent: Sunday, November 30, 2008 4:58 PM
>
> Sounds ok.
> But, doesn't the Info-Package header syntax still have to allow the
> piggy-backer to:
> 1) List multiple info packages
> 2) For each listed info package, provide the cid

Nope.  We've already said we're going to not bother doing multiple packages. (or at least I think people have agreed with that, I hope)
So the next question was on multiple body-parts.  Since INVITE, UPDATE, PRACK, SUBSCRIBE/NOTIFY, MESSAGE, and legacy INFO, can all carry bodies and not one of them defined a CID mechanism for the body part that was specific to their message method context, we shouldn't need to for INFO either.

A "piggy-backer" is an extension to SIP that piggy-backs bodies onto any message method types.  Geolocation is an example of one.  Since it's the responsibility of the piggy-backer to handle identifying its specific body-part and dis-ambiguating it from the method's, we don't have to do anything.  In other words, Geolocation would already have to deal with current INFO message and body syntax.

For example, let's suppose someone creates an INFO package for sending virtual location information in a game, using a content-type of application/pidf+xml.  (whether they should have done it in SIP vs. the media layer is orthogonal)  And let's suppose for whatever reason the SIP stack always adds Geolocation information of the UA's physical location.
Here is what it would look like:

----BEGIN----
INFO sip:bob at example.com SIP/2.0
Call-ID: 6994090221306382483-1149617605 at 192.168.1.1
From: <sip:alice at example.com>;tag=27285
To: <sip:bob at example.com>;tag=GR52RWG346-34
CSeq: 2 INFO
Via: SIP/2.0/UDP 192.168.1.1:5060;branch=z9hG4bK-6110000000000893
Max-Forwards: 70
Info-Package: virtual-loc
Geolocation: <cid:whereami@invalid>
Content-Length: [whatever]
Content-Type: multipart/mixed;boundary="boundary1"

--boundary1
Content-Type: application/pidf+xml

[xml stuff goes here]
--boundary1
Content-Type: application/pidf+xml
Content-Disposition: by-reference
Content-ID: whereami at invalid

[xml stuff goes here]
--boundary1--
----END----
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