W3C home > Mailing lists > Public > xml-dist-app@w3.org > May 2001

Re: Must understand mustUnderstand proposal

From: Doug Davis <dug@us.ibm.com>
Date: Thu, 3 May 2001 07:32:28 -0400
To: "Martin Gudgin" <marting@develop.com>
Cc: "XML Protocol Comments" <xml-dist-app@w3.org>
Message-ID: <OF7B7AFC5C.05300E94-ON85256A41.003F6E21@raleigh.ibm.com >
(forgive me if this already made it to the list but my mail
server was acting up this morning and I'm not sure it made it out)

My $0.02 ...

>1.    How do we make sure that the ultimate destination has processed/can
>process all of the mustUnderstand='1' headers targeted at it? Or do we
>need to bother? Will knowing that intermediaries have processed their
>headers, because there are no headers left in the message that are not
>targeted at the ultimate destination, be enough?

Yes, intermediaries must remove headers targeted for them.

>2.    Do we want to deal with the 'badly written' XMLP/SOAP
>that claims to have processed a header but in fact has not? See mail from
>Frank DeRose[2] for more detail on this question.

No we can't stop people from lying.

>3.    Does an intermediary *always* remove the headers targeted at it? If
>not then I think we need some way of annotating them as 'processed'.

Yes they must remove them.

>4.    What do we do about ordering? This is an issue particularly at the
>ultimate destination. What if this header is encountered before other
>headers marked mustUnderstand='1'? What if it is encountered after?

We should define the semantics of this header to include a statement
saying that it must be processed after all other MU headers.

>5.    This header needs to be marked mustUnderstand='1' :-)
>6.    This extension must be able to work by examining *only* the message
>that arrives at the ultimate recipient.
>7.    Is processing this at the ultimate destination enough? Or do we need
>to have evaluate this at every intermediary? <gulp>

I think this should be an untargeted header and therefore only processed
at the ultimate destination.  However, if it is targeted then we should
say that it MUST be understood (which is a given by the definition of MU)
and that it has no semantic side effect - in other words, I think we should
say that a targeted header of this type MUST NOT fault simply because it
is targeted.

>I think that'll do as a start point. Please chime in with your thoughts
>suggestions about the open questions and the semantics and we'll see how
>things progress. I'd like to be able to come up with a proposal by close
>play Monday if possible.

Great start!

Received on Thursday, 3 May 2001 07:33:32 UTC

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