Workflow Types. Two out of the box. To Infinity and beyond.
Out of the box Microsoft has two kinds of Workflows: Sequential and State Machine.
Sequential allows for parallel execution and looping but does not allow the hosting application to arbitrarily fire off an activity defined in the workflow.
The State Machine defines a set of states. Only one of the states may be executing at any time.
The Workflow runtime has no knowledge of these types. The runtime can handle any type of activity. StateMachineWorkflowActivity and SequentialWorkflowActivtity are types that inherit from Activity. Through overriding our new activity methods and implementing a designer we can create our own type of workflow that has no resemblance to the two out of the box.
I was able to build an interview workflow that allows for non-programmers to design an interview. The person designing the interview would decide the questions to ask, what choices were allowed for an answer, and apply rules to decide what the next question would be in the interview. Programming experience not required.
You could make a workflow design time work like a puzzle and then have it execute in order of the size of the pieces. With Windows Workflow we (The full-time) programmers can build a visual programming for others to build programs. Now that’s cool.