What Is Windows Workflow Foundation?

WF includes visual designers for use in Visual Studio 2008, which enable you to quickly design and develop workflow applications. By using workflow classes and custom data types, you can also define your workflow structure programmatically and develop the entire solution in code.

The following table shows some of the commonly used namespaces in WF.

System.Workflow.Runtime
Contains the WorkflowRuntime class and other classes and interfaces that control the workflow runtime engine and workflow execution
.

System.Workflow.Activities
Defines all of the built-in activities that you can add to workflows.

System.Workflow.ComponentModel
Contains base classes, interfaces, and modeling constructs that the workflow runtime engine uses to create activities and workflows.

The workflow runtime engine hosts all of the workflow instances and provides, among other functionalities, the ability to access running workflow instances, which enables you to make changes to running workflow instances at run time.

WF contains a set of standard activities to enable you to build workflows quickly; it also enables you to create your own custom activities that are tailored to your specific functional requirements.

References:

1.       The Workflow Way: Understanding Windows Workflow Foundation

2.       Windows Workflow Foundation

3.       Introduction to the Windows Workflow Foundation Rules Engine

4.       Windows Workflow Foundation integration with Windows Communication Foundation

5.       A Developer's Introduction to Windows Workflow Foundation (WF) in .NET 4

6.       The Workflow Way: Understanding Windows Workflow Foundation

7.       Windows Workflow Foundation: Creating a Custom Composite Activity