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Re: [AMG] Figure 2.1 suggested revision.

From: <john_ibbotson@uk.ibm.com>
Date: Wed, 14 Mar 2001 09:02:01 +0000
To: "Williams, Stuart" <skw@hplb.hpl.hp.com>
cc: "Henrik Frystyk Nielsen (E-mail)" <frystyk@microsoft.com>, "Jean-Jacques Moreau (E-mail)" <moreau@crf.canon.fr>, "Krishna Sankar (E-mail)" <ksankar@cisco.com>, "Lynne Thompson (E-mail)" <Lynne.Thompson@unisys.com>, "Marc Hadley (E-mail)" <marc.hadley@uk.sun.com>, "Mark A. Jones (E-mail)" <jones@research.att.com>, "Martin Gudgin (E-mail)" <marting@develop.com>, "Nick Smilonich (E-mail)" <nick.smilonich@unisys.com>, "Oisin Hurley (E-mail)" <ohurley@iona.com>, "Scott Isaacson (E-mail)" <SISAACSON@novell.com>, "Yves Lafon (E-mail)" <ylafon@w3.org>, "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
Message-ID: <80256A0F.0034169C.00@d06mta10.portsmouth.uk.ibm.com>



Stuart,
I like the revised diagram but have one minor revision which may address
Jean-Jaque's and Henrik's issues.

I believe that there are two types of handlers. Those that are visible to
the upper application layer and those that are completely enclosed within
the XMLP layer. The purpose of those entirely within the XMLP layer is to
provide additional funcionality to the infrastructure services used by the
application. These are services that the appication can rely on but does
not have to interact with. An obvious candidate is reliability. An
application assumes that the XMLP layer will handle reliable delivery but
does not need to interact or have visibility of how the layer does it. A
handler that understands retries, sequence numbers, block numbers and all
the other state variables associated with reliable delivery can exist
entirely within the XMLP layer - the application should not interact with
it. Other examples of handlers within the XMLP layer may include those that
support more complex message patterns.

The second type is where an application interacts directly with the
handler. The obvious candidate for this are handlers linked to payload
blocks where the contents of the message have to be delivered to the
application for further business processing.

I think this highlights an important distinction between the "application"
and "infrastructure" layers within XMLP.

John

XML Technology and Messaging,
IBM UK Ltd, Hursley Park,
Winchester, SO21 2JN

Tel: (work) +44 (0)1962 815188        (home) +44 (0)1722 781271
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Notes Id: John Ibbotson/UK/IBM
email: john_ibbotson@uk.ibm.com
Received on Wednesday, 14 March 2001 04:34:03 GMT

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