Workflow Services-Workflow visualization design with WCF and WF 4

Developers are increasingly using service-oriented architecture (SOA) as a way to build distributed applications. For inexperienced people, designing and implementing service-oriented distributed applications can be daunting. However, Microsoft. NET Framework 4 Enables Windows Communication Foundation (WCF) services to be implemented using Windows Workflow Foundation (WF) more than ever More simple.

WCF Workflow Services provide an efficient environment for writing long-running, persistent operations or services that are important for enforcing application protocols in the order in which they are ordered. The workflow services are implemented by using a WF activity that can use WCF to send and receive data.

In this article, I'll show you how to combine many of the features of WCF and WF introduced in the. NET Framework 4 to Model a long-running, persistent, and tested mortgage approval process for real estate companies without writing code. The intent of this article is not to provide an overview of WCF or WF, nor to introduce you step-by-step through the process of creating a work solution. I intend to highlight the use of the new important. NET Framework 4 features through a practical business application scenario. A complete work solution is included in the code download for this article.

Application Scenarios

First, let's outline an application scenario around which you build a workflow application. Contoso Housing is a real estate company that sells ordinary residential and premium apartments. To provide better customer service and an end-to-end purchase experience, Contoso works with three mortgage companies that help potential customers solve their mortgage needs. Each mortgage company offers a different interest rate. Contoso prioritizes it according to the interest rate of the mortgage vendor to ensure that the customer gets the best deal (the assumption that better interest rates make the house more likely to be sold).

Customers provide their mortgage request data through a WEB application. Each customer enters a customer ID, house price, down payment, loan term (year), payroll information, and some background check information.

The first step in applying for a workflow (see Figure 1) uses the data entered by the customer to filter the customer and determine eligibility, and then send the request to the mortgage vendor.

Figure 1 Mortgage approval process