Ian Foster wrote:
Steve:
A variety of semantics and connections are possible between a "WS-Resource" and an "entity that the WS-Resource repesents", including both your (a) and (b) below. I don't believe that the implied resource pattern implies that one particular approach be adopted.
The following are some rough notes on how we have chosen to handle things in the GT4 GRAM service. This may perhaps be relevant to your problem.
The approach that we take in GT4 GRAM is as follows:
1) A GRAM ManagedJobFactory defines a "create job" operation that:
a) creates a job, and also
b) creates a ManagedJob WS-Resource, which represents the resource manager's view of the job.
2) The ManagedJob WS-Resource and the job are then linked as follows:
a) Destroying the ManagedJob WS-Resource kills the job
b) State changes in the job are reflected in the ManagedJob WS-Resource
c) Termination of the job also destroys the ManagedJob WS-Resource, but not immediately: we find that you typically want to leave the managedjob state around for "a while" after the job terminates to allow clients to figure out what happened to the job after the fact
Regards -- Ian.
Ian, What is your fault tolerance strategy here? Is every ManagedJob WS-Resource hosted on the same host (and perhaps, same process) as the job itself? This would mean that there is no way for the managedjob EPR to fail without the job itself failing, but would require the entire set of job hosts to be visible for inbound SOAP messages. And prevent you moving a job from one node to another without some difficultly (the classic CORBA object-moved problem, I believe, though HTTP 304 responses would work if only SOAP stacks processed them reliably) I am trying to do a design which would enable (though would not require) only a subset of nodes -call them portal nodes- to be visible to outside callers, with the rest of the nodes only accessible to the portal itself. Once I assume this architecture, modelling the resources gets complex, as EPRs contain routing info that may become invalid if a portal node fails. -steve