Re: Question on section 2.7.1, Part 1

On Tuesday, Oct 8, 2002, at 15:40 US/Eastern, 
noah_mendelsohn@us.ibm.com wrote:

>
>>> 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
> info.
>
> What's the problem?  As soon as it hits an intermediary that wasn't
> updated, the header disappears.
>
Only if you target the header to a role the intermediary is playing. 
The example you give above would work quite well targetted at 
'.../none'. The whole message is available to any intermediary so the 
information is there if required. An 'active' intermediary could take 
some action based on the presence of a header targetted at '.../none' 
if it so desired.

> The alternative Henrik suggests, I believe, is:  either use an 
> application
> specific role (ICareAboutTime)
That would be fine too I think, provided everyone who played the role 
also understood the specific header - otherwise you would get the 
problem you describe.

> 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 don't like the above - I agree that it stretches the processing model 
uncomfortably far.

> 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
> imply.
>
+1.

Regards,
Marc.

--
Marc Hadley <marc.hadley@sun.com>
XML Technology Center, Sun Microsystems.

Received on Tuesday, 8 October 2002 17:41:24 UTC