Developing Workflow Activities
You can use the Windows Workflow Foundation APIs to create custom activities. You develop a custom activity by defining a custom activity class that either derives directly from the Activity, or from a default activity that derives from Activity. You have the option of customizing several aspects of your custom activity, such as serialization, validation, design, and default logic by using a set of related classes that encapsulate those specific pieces of functionality. Activity attributes are then used to reference these custom classes so that the custom logic is used instead of the default logic used by the attributes.
The use of attributes enables a client to discover the activity's capabilities. For example, a client can ask an activity if it has a BPEL (Business Process Execution Language)-format serializer without having to create an instance of either the activity or its serializer.
For a code sample that demonstrates how to create a custom activity, see the Simple Activity Sample.