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Workflow Management SystemThe Workflow Management System (WfMS) project is developed within the CoreGRID![]() | ||||||||
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The fist prototype of the system have been tested with workflows accessing resources available on the Grid provided by the EGEE![]() ![]() ![]() | ||||||||
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Papers
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Petri Nets in workflow modelingRecent studies have demostrated that the modling capabilities of Petri Nets outperforms other formalisms tanks to the following properties:
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< < | The swOperation allows to invoke sub-workflows, which implements the particular operation. In this case, the JobExecute workflow describe (using the Petri Nets formalism) the operation to perform in order to execute a task in the gLite Grid middleware. The sequence of operation is depicted in the following figure: | |||||||
> > | The swOperation allows to invoke sub-workflows. A sub-workflow implements a particular operation on a specific infrastucure. In this case, the JobExecute workflow describes (using the Petri Nets formalism) the operation to perform in order to execute a task in the gLite Grid middleware. The sequence of operation is depicted in the following figure: | |||||||
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< < | and the wait_for_termination transition also invoke a sub-workflow which can be expressed (using a polling strategy) in the following figure:
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> > | The JobRegister , JobSubmit operations are provided by the WMS via its Web Service interface, this make it possible to express the JobExecute sub-workflow in terms of atomic operations (actually Web Service invocation) the engine can understand and execute. The execution of a job in the gLite middleware consists in a jobSubmit (which semantics can be also obtained by invoking -- in sequence -- jobRegister and a jobStart ) and the monitor of the job activity until done. Job monitoring can be done via the WMS using the Logging and Bookkeeping Service![]() wait_for_termination task can be modelled using a sub-workflow which implement a specific monitoring strategy (polling or notification-based). | |||||||
Workflow Engine | ||||||||
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< < | The main component of the WfMS is the workflow engine. It is based on an semplification of the HLPN formalism. | |||||||
> > | The engine, represent the core component of the WfMS. It is based on the HLPN formalism and has the responsability to schedule workflow tasks accoring to their interdependencies keeping the overall state of the workflow execution. The engine deals with the non-determinism in Petri Nets providing an unique design capable of guarantee state consistency and ideally inifinite parallelism in task execution. | |||||||
-- SimonePellegrini - 19 Dec 2007 |