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Services

Meaning in Life

Persistence services

This feature allows you to save a WF instance to an external source (such

as a database). This can be useful if a long-running business process will

be idle for some amount of time.

Transaction services

WF instances can be monitored in a transactional context, to ensure that

each aspect of your workflow—or a subset of a workflow—completes (or

fails) as a singular atomic unit.

Tracking services

This feature is primarily used for debugging and optimizing a WF activity;

it allows you to monitor the activities of a given workflow.

Scheduling services 

This feature allows you to control how the WF runtime engine manages

threads for your workflows.

When you create an instance of the WF runtime engine in order to execute one of your work-

flows, you have the option of calling the AddService() method to plug in tracking or persistence

service objects (such as SqlWorkflowPersistanceService and SqlTrackingService) as well as any

customized service you may have designed. At this point you are able to execute a given WF

instance and allow these auxiliary services to further monitor its lifetime. 

In this introductory chapter, we will not build custom implementations of the core services,

nor will we dive too deeply into the default functionality of them. Here, we will focus on the build-

ing blocks of a workflow-enabled application, and we will examine numerous WF activities. Be sure

to check out the .NET Framework 3.5 SDK documentation for further details of the core services.