A workflow built on Windows Workflow Foundation is a component that requires an ad hoc runtime environment to function. The workflow runtime environment is represented by the WorkflowRuntime class. To host a workflow library, you create and configure an instance of the WorkflowRuntime class to operate on a particular workflow type. For performance reasons, you normally create the runtime environment only once in the application lifetime and make it serve all incoming requests. In a Windows Forms application, you initialize the workflow runtime in the form's constructor and destroy it with the form when the application shuts down. So how does this work if you're using ASP.NET?
Once you have a workflow component up and running, calling it from within a Web app or Windows Forms shouldn't be an issue. As far as Windows Workflow Foundation-based workflows are concerned, ASP.NET developers have only a few small issues to face that are mostly related to the nature of Web applications.

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