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RE: Correlation parameter in an XMLP Block

From: Krishna Sankar <ksankar@cisco.com>
Date: Fri, 30 Mar 2001 18:50:18 -0800
To: "Paul Denning" <pauld@mitre.org>, <xml-dist-app@w3.org>
Paul et al,

	Yep, I am also in favor of a context assertion, especially for web
services. This, as you describe, would be a "virtual pipe-line" through the
XMLP, between applications.

	The AM specifies the correlationID and where we manifest it physically is a
binding issue. For example for http/SOAP, we might add a <context/> block,
for browsers there might be only the cookies, ...

	On a related note, I can see even the XMLP using the correlationID for some
purposes like reliable messaging et al. So there is a (weak) argument that
the correlation could be meaningful for the XMLP layer as well.

	Your question about a "conduit" from the XMLP layer to the application is
interesting. I had similar discussions at the ebXML TRP.

	The question I had was, if we have a scheme to sign/encrypt the headers and
if the XMLP layer unpacks the message, the application above will not be
able to get to the certificates (for identification & authentication
purposes) and signatures. XMLP captures this context (related to the
underlying layers) in the BindingContext. I assume any application specific
context would be in the message.


|-----Original Message-----
|From: xml-dist-app-request@w3.org [mailto:xml-dist-app-request@w3.org]On
|Behalf Of Paul Denning
|Sent: Friday, March 30, 2001 2:43 PM
|To: xml-dist-app@w3.org
|Subject: Correlation parameter in an XMLP Block
|I've been thinking about Marwan's question of why the concept of causality
|is needed.
|Its clear to me that it is needed, its just a matter of where you put it.
|The XMLP Layer does not need it.
|If the correlation id is passed down to the XMLP as a parameter of the
|XMLP_UnitData.send, what is the XMLP Layer supposed to do with it?
|If it goes into an XMLP Block, then it should be the XMLP Module that
|constructs the Block (containing the correlation id).  The XMLP Layer does
|not look at or process the Block (or does it?)
|If RPC is a module, and RPC requires causality and a correlation id, then
|an XMLP Block seems like the logical place to put the correlation id.
|The XMLP Layer needs to provide a conduit for the upper layer modules to
|provide information to the lower layer bindings; otherwise, how would the
|lower layer binding (e.g., for HTTP) know when to send an HTTP
|response and
|what should go in it?
|The "conduit" is something currently missing from the AM.  We need the
|concept of a "Context", which can be defined as
|the runtime relationship between the XMLP Layer, the underlying bindings,
|and the upper layer modules.
Received on Friday, 30 March 2001 21:49:27 UTC

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