Windows Server AppFabric builds on top of .NET Framework's Windows Communication Foundation and Windows Workflow Foundation (WF) and simplifies the scenario of hosting, managing, and monitoring long-running and durable workflows. Windows Server AppFabric's persistence enables two key use cases, which we'll look at now.
Windows Server AppFabric is a middleware platform and for most of the deployments, it will run on a distributed server farm. Windows Server AppFabric's Hosting subsystem uses its persistence capabilities to allow WF-based workflows to become scalable and durable. Windows Server AppFabric's provides its default SQL Server based persistence provider (also known as Instance Store), which allows these workflows to become durable.