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Figure 26-23.

The fully configured SendActivity

Figure 26-24.

Communicating with a WCF service

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Source Code

The WFMathClient example is included under the Chapter 26 subdirectory.

Building a Reusable WF Code Library

These first examples allowed you to play around with various WF activities at design time, interact

with the workflow runtime engine (by passing custom parameters), and get into the overall WF

mind-set using console-based WF hosts. While this is great from a learning point of view, I bet you

can easily envision building workflow-enabled Windows Forms applications, WPF applications, or

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ASP.NET web applications. Furthermore, I am sure you can imagine the need to reuse a workflow

across numerous applications by packaging the functionality within a reusable .NET code library.

The next WF example illustrates how to package workflows into *.dll assemblies and make use

of them from a hosting Windows Forms application (which, by the way, is the same process as host-

ing an external workflow within any executable, such as a WPF application). We will design a

workflow that models the basic process of checking credit to place an order to purchase an auto-

mobile from the AutoLot database created in Chapter 22.

Begin by selecting a Sequential Workflow Library project named CreditCheckWFLib (see 

Figure 26-25) and rename your initial file to CreditCheckWF.cs.

Figure 26-25.

Creating a Sequential Workflow Library project 

At this point, you will be provided with an initial workflow designer. Be aware that a single

workflow code library can contain multiple workflows, each of which can be inserted using the

Project ➤ Add New Item dialog box. In any case, add a reference to your AutoLotDAL.dll assembly

created in Chapter 22, and update your initial code file to import the AutoLotConnectedLayer name-

space: