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RE: REST, Conversations and Reliability

From: David Orchard <dorchard@bea.com>
Date: Tue, 6 Aug 2002 21:58:11 -0700
To: "'Mark Baker'" <distobj@acm.org>
Cc: <www-ws-arch@w3.org>
Message-ID: <013201c23dcf$08ee1320$140ba8c0@beasys.com>

I totally agree with the quote.  But the quote was used for different
reasons.  In the past, people tried to make distributed systems by
"extending" the wire, which is totally broken.  You can't hide the
latency/unreliability/etc. of the underlying protocols when building
distributed applications.

But in my world, the Web Service *knows* that it is distributed.  So
therefore the application AND the reliability solution both are fully aware
of being remote.  You are confusing web services that are message-based
(which I prefer) with RPC-style (where it looks like a remote procedure
call).  That's yet another reason why many of us prefer asynchronous
message-based solutions, because it acknowledges the distributed nature of
the applications.  You believe that method names in messages=rpc, whereas I
equate synchronous/hide-the-remote-aspect=rpc.  Interestingly, I think that
you equate the containment of "P" in RPC to be sufficient to characterize as
RPC, whereas I equate the "R" (that is making a local procedure call look
remote) and the "C" (synchronous blocking call) to be RPC.  Perhaps another
way of looking at it.


> -----Original Message-----
> From: Mark Baker [mailto:distobj@acm.org]
> Sent: Tuesday, August 06, 2002 6:55 PM
> To: David Orchard
> Cc: www-ws-arch@w3.org
> Subject: Re: REST, Conversations and Reliability
> On Tue, Aug 06, 2002 at 03:48:34PM -0700, David Orchard wrote:
> > But I'll decline the challenge to show proof of something
> that I'm hoping
> > we're going to create.  I understand that you think we've
> tried and failed,
> > but I think we have some new technology - like the web
> > WSDL - as well as past experience that will help us.  And I
> think we can use
> > these technologies in ways that loosely couple reliability
> to application
> > semantics.
> I just wanted to point out that some aspect of a reliability solution
> may be reusable in a loosely coupled manner.  For example,
> message ids.
> But a complete SOAP based reliability solution cannot be.
> BTW, I just found this, a better description of the infamous
> "A Note on
> Distributed Computing" paper than the paper itself provides (by Jim
> Waldo, of course);
>   "In particular, we argued that distributed infrastructures must
>    present a model of partial failure to the programmer, since only at
>    the application level can such failure be dealt with; must
> deal with
>    concurrency issues, rather than leaving them to the infrastructure;
>    and must at the application level realize what parts of the program
>    are local and what parts are at least potentially remote."

Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
Ottawa, Ontario, CANADA.               distobj@acm.org
http://www.markbaker.ca        http://www.idokorro.com
Received on Wednesday, 7 August 2002 00:59:47 UTC

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