Hi Andrew,
I’d echo the points raised by Steve/Ian/Donal but appreciate what I think may be your motivation for this exercise (some simple definition of workflows that OGSA services can work with). I think the key is “that which OGSA services can work with”.
I think a simpler approach may be to define clearly what OGSA services expect (semantics, formats) from workflow services and what control points are to be exposed by these services to allow OGSA services to “manage” these workflow services and/or the workflows they instantiate and drive. Given this OGSA would specify an “OGSA”(?) query/command interface that services would additionally expose/implement (in addition to what they already implement/expose i.e. a composition). OGSA services would then issue requests (that adhered to this standard) and get responses (to this standard) which would describe just the elements that would be required for example in a scheduling decision. A response for scheduling for example would define the nodes and connections (which might look somewhat like your example) so that a scheduler can understand dependencies.
The request/command interface may also support operations like to launch a workflow, rewind a workflow etc (some of these commands may also mimic BES requests). We need a standard (OGSA compatible) way to interact with workflow engines and workflows but probably not a new WFDL. Even in defining these interaction interfaces we should be careful not to “reinvent the wheel” if there is standards which we can define a *profile* to simplify for OGSA needs.
Defining, building and describing these workflows would be outside the purview of this exercise and this is where the large body of work can be leveraged by the solution implementers.
Ravi
From: ogsa-wg-bounces@ogf.org [mailto:ogsa-wg-bounces@ogf.org] On
Behalf Of Andrew Grimshaw
Sent: Wednesday, November 29, 2006
5:52 PM
To: ogsa-wg@gridforum.org
Subject: [ogsa-wg] Materials for
tomorrows call
All,
Steve McGough and I were asked to prepare a discussion around workflow for the telecom tomorrow. Attached is a short slide deck and some XML examples – to be explained during the call.
I have another meeting in which I am presenting that runs from 7-9 am eastern, so will miss the opening of the OGSA call. If for some reason I am late, Mark can present.
A
Andrew Grimshaw
Professor of Computer Science
University of Virginia
434-982-2204
grimshaw@cs.virginia.edu