Programming .NET 3.5

Using Windows Workflow

And, you know what? Nowadays, that won't be necessary—WF will do the heavy lifting for you. In the rest of this chapter, we'll take a high-level view of the WF tools and toolkit, to provide you with an introduction to what WF can do for you.

Activities

Activities are the fundamental building blocks of WF workflows. As building blocks, they represent the basic steps within a workflow. In essence, a workflow is developed as a tree of activities, where a specific activity makes up an individual unit of execution. You will likely develop your WF solutions by assembling specific activities, which, as a result of their nature as reusable objects, can themselves be compositions of more than one activity.

The two types of WF activities are known as basic activities and composite activities. As its name suggests, a basic activity is custom-coded to provide its function set. It follows, then, that a composite activity is built out of other existing activities (both basic and composite).

A Simple Workflow Application: HelloWorkflow

Let's begin by creating a simple workflow. Open Visual Studio 2008 and choose New Project from the File menu. Select Sequential Workflow Console Application from the list of installed templates, and name the project (of all things) HelloWorkflow (see Figure 12-4).

Having successfully created your project, you should see an empty Sequential Workflow design pane like the one shown in Figure 12-5.

You should also see a toolbox pane containing several ...