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Re: Question on section 2.7.1, Part 1

From: <noah_mendelsohn@us.ibm.com>
Date: Tue, 8 Oct 2002 15:40:15 -0400
To: Marc Hadley <marc.hadley@sun.com>
Cc: "Henrik Frystyk Nielsen" <henrikn@microsoft.com>, "Martin Gudgin" <mgudgin@microsoft.com>, moreau@crf.canon.fr, Nilo.Mitra@am1.ericsson.se, www-archive@w3.org
Message-ID: <OF661970DF.3C8C0233-ON85256C4C.006BBCCD@lotus.com>

Mark Hadley asks:

>> Why is it important that the header *not* be "mustUnderstand='1'" ? 

The scenario is:  a bunch of SOAP implementations get deployed and set up 
as intermediaries and endpoints along a path.  Afterawhile, I discover 
there is some information I want to include in my messages and that 
information is really for anyone who cares.  Maybe I want to put in a 
"TimeSent" header.  Is it mU?  No.  If you don't care that's harmless.  It 
will only be understood selectively as individual intermediaries are 
redepoloyed with software that can take advantage of the sending time 

What's the problem?  As soon as it hits an intermediary that wasn't 
updated, the header disappears.

The alternative Henrik suggests, I believe, is:  either use an application 
specific role (ICareAboutTime) or a general relaying Role 
(IDontRemoveNotUnderstoodHeaders) and claim that any node implementing the 
chosen role agrees not to remove headers, even headers that it doesn't 
process.  I'm concerned that this is at least a serious stretch of the 
processing model which says:  if you play the role, you must remove it. 
You can only reinsert if you have some specific reeason based on 
processing.  To read that as:  "well actually, you can leave it in if you 
know something special about the role"  seems to go well beyond what we 

So, there's a use case and a problem, I think.  How serious is a matter of 
judgement, which is why I'm waffling on raising as a real issue.

>> I agree that role shouldn't be overloaded in this manner.

I'm pretty sure I do too.  Thanks.

Noah Mendelsohn                              Voice: 1-617-693-4036
IBM Corporation                                Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142
Received on Tuesday, 8 October 2002 15:42:54 UTC

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