[ogsa-wg] RE: GRIDtoday Edition: Tony Hey: 'Challenging Times for GGF & Standards'

[Ian Foster]

Savas:

I wondered when you'd join the debate, and as usual your comments are very 
much to the point.

At 06:09 PM 3/1/2005 +0000, Savas Parastatidis wrote:
>Please note that I am not suggesting that WS-RF (and WS-Transfer for
>that matter) is not useful in certain cases. Indeed, in the systems
>management area it may make sense to use them. However, what it is being
>proposed in the OGSA working group (if I understand correctly) is that
>WS-RF be used as the foundation for all high-level services.

I don't think that the OGSA working group would argue for using it as a 
foundation for "all high-level services," but I understand that some people 
fear that this is intended.

For system management applications (a major focus of OGSA), I do believe 
that there is value, as you also note.

>However, a difference
>that I personally see between the WS-RF/WS-Notification and WS-Transfer/
>/WS-Eventing/etc. camps is that the latter is much simpler and

"much simpler" is a relative term of course, but I think we should also 
remember that there isn't a lot to even the "more complex" 
WSRF/WS-BaseNotification. See Blackberry note below.

>lightweight. Most importantly, the MS suite of specifications is not
>promoted as the uniform, underlying suite of common messaging behaviours
>for all high-level services as WS-RF seems to be. Instead it is some

That's not my understanding of WSRF.

>patterns that are available to be used where they are appropriate. Also,
>WS-Transfer is lightweight so it can be used in very-small-factor
>devices.

I've seen WSRF implemented on a Blackberry, with the complete 
SOAP-WSRF-WSN-WSDM stack occupying 102KB. I *think* that the "small factor" 
issue is a red herring. If you want to run on something with just 64KB 
memory, you probably shouldn't be using Web services.

>So, it would be interesting to understand from the WSRF architects where
>they feel the WSRF approach is and is not appropriate. E.g. is it
>appropriate for interactions with multiple resources? Should it be used
>in the design of all high-level Grid services? What are the semantics of
>the 'destroy' messages?

Here's my opinions:

* WSRF (or indeed any WS-I-compliant specification) should be used when and 
where it's appropriate.

* Semantics of destroy: these are defined fairly clearly in the 
WS-ResourceLifetime specification.

* Interactions with multiple resources: I think that's a red herring. E.g., 
a job factory can return EPRs to WS-Resources representing jobs, thus 
allowing individual jobs to be monitored and controlled, if needed.  The 
factory can also maintain a service group representing all jobs, and then 
support operations that allow a client to "destroy all jobs that match a 
certain pattern" (for example). It's not an either/or.


_______________________________________________________________
Ian Foster                    www.mcs.anl.gov/~foster
Math & Computer Science Div.  Dept of Computer Science
Argonne National Laboratory   The University of Chicago
Argonne, IL 60439, U.S.A.     Chicago, IL 60637, U.S.A.
Tel: 630 252 4619             Fax: 630 252 1997
         Globus Alliance, www.globus.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.ogf.org/pipermail/ogsa-wg/attachments/20050303/aaa90222/attachment.htm