[glue-wg] GLUE2.0's Computing Element

[Gerson Galang]

Hi Laurence, Sergio,

For me a cluster represents a set of resources that are managed, which
> essentially is a batch system with a master server. The queue represents
> two things; an end point and a policy.  The GRAM service is an interface
> to the batch system and therefore an end point.
>
> How you represent these things depends on the implementation.
>
> 1) If the job attributes are passed to the batch system, then based on
> these it should decide which queue (policy) best matches the
> requirements. In such a scenario,
> you would then publish two services (end points), one for each batch
> system, and the gateway should route the job to the relevant batch
> system based on which service (end point) was used.


What you have desribed above might not work for us.  The GRAM does not have
the restriction of only being able to submit (interface) to one batch system
(PBS server for our case). Even if we have more than one cluster at our
site, we can easily pick which queue and cluster we want to run our job on
by having the queue element specified in the RSL..

<queue>small at pbsserver1</queue>

An instance of the WSGRAM service can only have one unique endpoint and if
we implement the setup you've described above, we'll need to run one GT4
container for each batch system (cluster) we are managing here at our site.

2) If the the job requirements are not passed though, then you have to
> consider each queue to be a different endpoint and hence have a service
> (end point) per batch system and per queue (policy). The gateway would
> then route the job also to the correct queue.


Same comment as above.

In either case the policy (queue) would be advertised as a share.
> However, in the second case I am not sure how the end point is linked to
> the policy.


Here's how we can probably fix the problem..
- remove the association between the ComputingService and Share
- directly link Share to the ComputingElement (the queuing system). The
ComputingElement won't be a computing element if it doesn't provide at least
one Share (a queue).
- multiplicity of the link between the ComputingElement and ComputingService
should be "1..*" on the ComputingElement side

Attached is  a UML diagram of the changes I made to the original diagram.

Cheers,
Gerson
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