Windows Workflow Foundation simplifies the process of creating stateful, long-running, persistent workflow applications. The workflow runtime engine manages workflow execution and enables workflows to remain active for long periods of time and survive application restarts. This durability is a key tenet of Windows Workflow Foundation. It means that workflows can be unloaded from memory while awaiting input and serialized into a persistent store, such as a SQL database or XML file. Whenever the input is received, the workflow runtime engine loads the workflow state information back into memory and continues execution of the workflow.
Windows Workflow Foundation provides the SqlWorkflowPersistenceService that integrates well with Microsoft SQL Server 2005 Express, SQL Server 2000 or later, or SQL Server 2000 Desktop Engine (MSDE) to persist workflow information easily and efficiently. You can also create your own persistence service to store workflow state information any way you want by deriving from the WorkflowPersistenceService base class.