[ogsa-bes-wg] Proposed changes to Spec.

[Andrew Grimshaw]

Ian,

My understanding of the OGSA policy is that OGSA does not mandate WS-Names .
instead it encourages them WHERE THEY ARE APPROPRIATE. That decision is up
to individual working groups, and perhaps a design team working on a
profile. The policy, in my mind, is NOT that WS-Names may not be mandated by
OGSA specifications. 

 

In the case of OGSA-BES, at the last GGF in Boston the working group
discussed at great length the pro's and cons of WS-Names, opaque EPR's, and
abstract names (i.e., uri's with a few properties). The overwhelming
majority preferred WS-Names (an explicit, comparable return value) (8 to 2).
A further discussion was held as to whether the WS-Names should have both
abstract names AND resolvers, and the vote was 4 to 1 for having a resolver,
with many people indifferent. 

 

Thus, OGSA-BES will have* WS-Names as return values and input parameters.

 

We also discussed "eventing" at some length. I have not yet typed in my
notes, the three high order bits were:

1)       The container is the right place to emit the events

2)       Clients must explicitly subscribe to events ("use filtering from
the container, not specific registration" . I'm not sure what that means, I
think we will need to discuss this in a call and remind me.)

3)       Events are state transitions of the activities

Andrew

 

*Of course the document still has to go into public comment, get revised,
and hopefully some day be approved by the GFSG. What is really in the
document may change between now and then.

 

  _____  

From: owner-ogsa-bes-wg at ggf.org [mailto:owner-ogsa-bes-wg at ggf.org] On Behalf
Of Ian Foster
Sent: Wednesday, October 26, 2005 11:40 AM
To: Darren Pulsipher; ogsa-bes-wg at ggf.org
Subject: Re: [ogsa-bes-wg] Proposed changes to Spec.

 

Darren:

I would like to argue against your proposed operations on the grounds of
fragility and scalability.  Your operation definitions require that a client
keep track of the set of activities to be monitored and controlled. That's a
big burden to place on the client. 

I suggest (as we have also suggested in earlier communications to BES-WG)
that we should instead allow the user to specify a set of activities that
are to be monitored or controlled in terms of their properties, not names.
E.g., "activities that belong to me", "activities that involve executable
Foo", "activities that have been running for over 2 hours."

A natural way of modeling this is to represent the set of activities
associated with your jobs as a WS-ServiceGroup Service Group, and then use
queries on the service group to specify the activities to which an operation
applies.

Regards -- Ian.

PS: As noted in previous emails and conversations, I also believe that the
use of WS-Names rather than vanilla EPRs is inappropriate. I also believe
that it is inconsistent with the OGSA policy that WS-Names cannot be
mandated in OGSA-related specifications.



At 08:52 AM 10/26/2005 -0600, Darren Pulsipher wrote:



I have spent some considerable time with the document.
I know far more than I planned, but it was good time spent.
I think we should discuss these items in our meeting on Thursday.
I have posted some changes to the document but would like to discuss
these items before I make these changes to them.

There are some fundamental problems/questions that we need to resolve.

1. How do we resume from where we left off. There is no Resume anymore
so we are putting the responsibility to the submitter or controller to
keep track of states. We can only use RequestActivityStateChanges to
suspend something and if I want to suspend 1000s of activities that
means I would need to first do a GetActivityState save the states and
then call RequestActivityStateChanges without any of the activities
changing state. That is not going to happen. So I propose we do the
following:
- Add the following interfaces:
SuspendActivites(WS-Name[] activityIdentifiers)
ResumeActivities(WS-Name[] activityIdentifiers)

Or we add one interface
PerformOnActivites("Suspend" | "Resume", WS-Name[] activityIdentifiers)

2. Another problem is how do we terminate an activity. The States that
are available are "Terminated" and "ShuttingDown". According to the
state net the activity is moved to the "ShuttingDown" and then to
"Terminated" so requesting RequestActivityStateChanges for activities
with "ShuttingDown" means it should move to the ShuttingDown state but
it will move the activities to the "Terminated" state. This can be very
confusing. So I suggest we add another interface.
- Add the following interface:
TerminateActivities(WS-Name[] activityIdentifiers)

Or add another possible argument to the interface.
PerformOnActivites("Suspend" | "Resume" | "Terminate", WS-Name[]
activityIdentifiers)

3. Another question that is not clear in the spec is if an action
(staging in or staging out) moves into an exception state does that mean
that the activity moves into the exception state right away or does it
mean that it ever moves into the exception state. Does it mean that if
one of the actions moves into an exception state that all other actions
are halted and moved to the exception state and then the activity?
- I proposed that actions state have no impact on the activity state. If
an action has an exception or is terminated then it should not have any
impact on the activity what so every.

4. Another not so important change but it might help clarify some
confusion and allow for extendibility later on would be to get rid of
the "ExecutionPending" and "ExecutionComplete" and make the "Running"
state a composite state like the "StagingIn" and "StagingOut" states.
This will give the ability to handle complex multiple application
execution definitions that the JSDL group is looking at for the next rev
of the Job Definition. This will allow for multiple Application actions.
This is not workflow. Nor should it be considered the start of workflow.
This just allows for extendibility easily.


Darren Pulsipher

_______________________________________________________________
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 <http://www.globus.org/> 

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