RE: Different Levels of Reliable Messaging

Ugo

You suggested three layers: transport, SOAP & application. I actually think
there are four: transport, SOAP, Reliable Messaging and Application. Where
the Reliable Messaging layer would cover most (but not all) of the reliable
messaging functionality I described.

I don't think that RM should be automatically included in the SOAP layer as
many SOAP implementations won't need it. The real way to solve this is to
use SOAP Features/Modules to handle the extensions required for RM.

Having said that, I do think that RM does spread over multiple layers if
only because sometimes the decision on which action to take when doing
Reliable Messaging with Recovery (level 3) can only really be done at the
application layer as only it can understand the consequences of each
alternative action. However the re-sending of the messages, etc, would be
done at the lower RM layer.

The other difference is that you can do RM at the transport layer using
solutions that provide equivalent functionality to Level 1 (Simple Reliable
Messaging) or Level 2 (Connection based Messaging). For example MOM
transports or solutions based on HTTP/R. In this case doing similar work at
the RM layer (between SOAP and the application) might not offer much extra
benefit. However this not true if you include intermediaries in the message
path but - that's another story for another email ;)

David

-----Original Message-----
From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Thursday, December 12, 2002 3:48 PM
To: Burdett, David; www-ws-arch@w3.org
Subject: RE: Different Levels of Reliable Messaging


David,

Do you think it would make sense to plot the levels you describe against the
other dimension of Web services reliable messaging, i.e. implementation at
the transport layer, the SOAP framework layer, or the application layer? In
other words, is it easy enough, according to your experience, to recommend
an optimal implementation using one of those layers, once you decide which
reliable messaging level you want to support? Or is it more difficult than
that, and might even involve a combination of layers in some circumstances
(e.g. SOAP layer + application layer)?

Thank you,
Ugo

Received on Thursday, 12 December 2002 20:23:21 UTC