[Top] [All Lists]

Re: [ontolog-forum] The Open Group SOA Ontology

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ed Barkmeyer <edbark@xxxxxxxx>
Date: Fri, 18 Jul 2008 12:45:53 -0400
Message-id: <4880C8C1.7010000@xxxxxxxx>
John,    (01)

you wrote:    (02)

> Message passing is the most fundamental of all these methods.
> Subroutine call is one very constrained special case.  The O-O
> paradigm is another special case.
> EB> With all due respect, I think the request/response interaction
>  > paradigm is fundamental to "service-oriented".  As discussed in
>  > other venues, the actual technical interaction can be more complex
>  > than request/response, but the fundamental paradigm cannot be.
> I agree, but I would say that "request/response" is another special
> case of message passing.  ...    (03)

We are on different wavelengths here.  Message passing is a nominal 
model for pretty much every variety of communication that is 
recipient-specific, as distinct from "broadcast-like".    (04)

I agree that request/response is a special case.  The important idea is 
that the request "message" is targeted to a specific "role" in the 
system that is nominally played by a single correspondent, who may or 
may not be known to the requestor.  And the message is a request for a 
service that the correspondent is expected to provide.  And the response 
is a message directed to the requestor that may include the provision of 
the service, or just the notification that the service has occurred, 
will occur or won't occur.    (05)

> There are many kinds of message types that
> are neither requests nor responses,     (06)

And their relationship to an SOA is undefined.    (07)

> and not all requests trigger a
> response from the intended recipient.  For example, a request sent
> to an executive might be read by a secretary, who forwards it to
> an assistant, who sends a response.    (08)

But from an SOA point-of-view, the request goes to the _role_ -- from 
outside, the "executive" denotes a person as the image of the "office" 
-- and the participant that actually plays that role -- the "office" -- 
is the provider.  The internal process of the office is encapsulated -- 
the requestor neither knows nor cares how that actually works.    (09)

In the same way, Zoom Motors can issue a request for a metal part to a 
"first-tier supplier" Metals-R-Us who functions as a broker and chooses 
one of several small foundries to make those parts.  From the 
point-of-view of Zoom Motors, Metals-R-Us supplied the parts.    (010)

-Ed    (011)

Edward J. Barkmeyer                        Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263                Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263                FAX: +1 301-975-4694    (012)

"The opinions expressed above do not reflect consensus of NIST,
  and have not been reviewed by any Government authority."    (013)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (014)

<Prev in Thread] Current Thread [Next in Thread>