Subject: [Simple] IMDN: Do we need record-route?

From: Miguel Garcia <[email-masked]>
Date: Thu, 26 Oct 2006 12:42:43 +0300

Hi:

First, I want to express my support for the current version of the IMDN 
draft, I think it is going in the right direction. Especially, it is 
easier to read than earlier versions.

The draft defines the Original-To, IMDN-Route, and IMDN-Record-Route 
CPIM headers. I see the need for this CPIM headers when SIP is the 
transport protocol. However, I don't find a reason for them if MSRP is 
the transport protocol. I think endpoints will send IMDNs through the 
same MSRP logical session where the IM was received. If at the other 
side there is an intermediary, for sure there is some logic on top that 
is able to route back to the original sender.

So is there a usage of these headers in MSRP?

BR,

        Miguel
-- 
Miguel A. Garcia           tel:+358-50-4804586
sip:[email-masked]
Nokia Research Center      Helsinki, Finland

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From: Eric Burger <[email-masked]>
Date: Fri, 27 Oct 2006 12:22:54 -0400

On the one hand, good point. On the other, won¹t the MSRP relays be
transparent? If so, then I would leave the specification as is, especially
since once we take it out someone will want to gateway from MSRP to SMS ;-)

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From: Miguel Garcia <[email-masked]>
Date: Mon, 30 Oct 2006 09:38:58 +0200

I am not really convinced that we need IMDN record route. Let's try to 
analyze it.

I would expect that an MSRP IM receiver that gets a request for IMDN, 
builds an MSRP SEND request that has the same headers (namely From-Path 
and To-Path) than any other regular SEND request that the endpoint would 
send. So, if the network (relays, intermediaries, mixers, etc.) is able 
to route any asynchronous SEND request that such endpoint would send, it 
would route any IMDN in the same manner.

I would not expect that the endpoint has to dig into the IMDN CPIM 
headers of the received IM to build an MSRP SEND request (that carries 
the IMDN) in a different manner than any other regular SEND request. Not 
having to take a look at the record-route headers will simplify 
implementations substantially, because the IMDN will be considered a 
special payload of a regular SEND request (at the moment the spec. 
considers it a special payload f a special SEND request).

I would therefore, advocate for removing these headers in MSRP IMDN.

/Miguel