Windows Server AppFabric offers an Instance Control mechanism that allows issuing control commands to be executed against persisted instances. Instance Control also allows the ability to retrieve commands queued against a persisted workflow instance. This two-way communication enables a decoupled mechanism of handling, retrieving, and executing control commands against a persisted instance.
The Instance Control provider is responsible for providing access to an Instance Control object. Windows Server AppFabric provides a default implementation of the Instance Control provider called the SqlInstanceControl
provider that runs on top of SqlWorkflowInstanceStore
. We learned about SqlInstanceControl
in our third recipe of this chapter, titled Programmatically controlling persisted workflow instances.
In this recipe, we will focus on building a custom Instance Control provider.