Persistence services solve the problems inherent in executing long-running workflows. Many business processes take days, weeks, and months to complete. We can't keep workflow instances in memory while waiting for the accountant to return from the beaches of Spain and approve an expense report.
Long-running workflows spend the majority of their time in an idle state. The workflow might be idle waiting for a
Delay activity to finish, or for an event to arrive in a
HandleExternalEvent activity. When a persistence service is available, the runtime can persist and then unload an idle workflow. Persistence saves the state of the workflow into long-term storage. When the event finally arrives, the runtime can restore the workflow ...