arguments to ICluster.vm_create() method

[Andre Charbonneau]

Hi,
I'm currently working on adding MyProxy support to the cloud scheduler
and I have a question regarding the arguments of the
ICluster.vm_create() method.

Currently, most of the arguments are taken from the job and passed on
to the vm_create method, individually. To implement MyProxy support,
I need to pass a few more arguments to the vm_create() method, such as
the myproxy server, port and creds name. But this only makes sense
for the case of the Nimbus cluster subclass, so I find that updating
the base class vm_create() method definition to include these new
attributes is not a good OO design decision.
One way to go around the problem, would be for the vm_create() method
to accept a Job instance, and then the subclasse's implementation of
the vm_create method will simply extract what is needed from the given
Job instance. This would also have the benefit of making the
vm_create() method signature more simple and not having to modify the
vm_create() method interface when new attributes are added to the Job
class in the future (if needed). One downside to the above approach
would be that it would create a dependency between the ICluster and
Job classes.

Any comments, suggestions?

Best regards,
Andre

[Andre Charbonneau]

OK, the changes have been made on the vm-create-refactoring-dev, ready
to be merged into the dev branch.

Thanks,
Andre