Subject: [Simple] MSRP: Wrapped types

From: Ben Campbell <[email-masked]>
Date: Fri, 27 Feb 2004 14:52:53 -0600

Another issue came up during the discussions several of us had a SIPIT. 
I am separating this out from the MSRP/SIMS harmonization email, as it 
is orthagonal to that.

Several people commented that the existing "accept-types" and 
"accept-wrapped-types" were overly confusing and error prone. To recap, 
the point of this mechanism is to allow an MSRP device to accept a 
number of formats, but require them to be wrapped in an envelope of some 
sort. The motivation behind this is that a CPIM gateway may allow any 
number of content-types, but insist that everything be wrapped in a 
message/cpim envelope.

The existing mechanism says that any format listed in "accept-types" can 
occur anywhere in a body, including at the root. Formats listed in 
"accept-wrapped-types" cannot occur at the root; that is, they must be 
wrapped inside of some format listed in "accept-types". This solves the 
problem, but it is pretty complicated and difficult to understand.

Two possible alternatives were offered:

1) Get rid of the "accept-wrapped-types" attribute, and instead add an 
attribute that means "I require CPIM". This would mean that all content 
must be wrapped in message/cpim envelopes.

2) Generalize option 1 a little bit by adding an "envelope" attribute. 
This attribute would contain a single format entry. All content must be 
wrapped in that format.

And of course, there is an implied item 3: Leave it as is.

Thoughts?

Thanks!

Ben.

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From: Paul Kyzivat <[email-masked]>
Date: Sun, 29 Feb 2004 02:18:52 -0500

It is only confusing until you think about it. I think we should leave 
it alone - or maybe just clarify the wording a bit.

	Paul

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From: "Niemi Aki (Nokia-M/Espoo)" <[email-masked]>
Date: Sat, 28 Feb 2004 20:28:38 +0200

> This attribute would contain a single format entry. All content must be 

#2 would work for me and would be better than #1, since it allows for
other wrappers that might potenitally be useful (like always requiring
signed messages).

Additionally, one might imagine needing this attribute to be 
multi-valued. Come to think of it, a case where everything needs to be 
both signed and CPIM wrapped would also require ordering in this 
attribute to count, so that the sender would know in which order to 
apply the listed wrappers - first cpim, then multipart/signed.

But a single-valued envelope would suffice for the majority of usages, 
including the multiparty chat and CPIM gateway, which I think are the 
most important ones at the moment.

Cheers,
Aki

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From: "Niemi Aki (Nokia-M/Espoo)" <[email-masked]>
Date: Sat, 28 Feb 2004 20:28:38 +0200

Cheers,
Aki

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From: Ben Campbell <[email-masked]>
Date: Sun, 29 Feb 2004 05:25:40 -0600

Niemi Aki (Nokia-M/Espoo) wrote:
>> attribute that means "I require CPIM". This would mean that all 
>> content must be wrapped in message/cpim envelopes.
>>
>> This attribute would contain a single format entry. All content must 
>> be wrapped in that format.
> 
> 

If it is multivalued, then it is affectively the same as the current 
version. Maybe even a little more complex if we do ordering.

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From: Ben Campbell <[email-masked]>
Date: Sun, 29 Feb 2004 05:25:40 -0600