MSDN Magazine - July 2008 - (Page 111)

Dr. James mCCaFFrey TesT Run Introduction to WCF Testing Whether you are new to Windows® Communication Foundation (WCF) or have worked with it a bit, there are some testing techniques and principles that will make your WCF work easier. There are several ways to think about what WCF is—I tend to think of WCF services as a major extension of Web services. Like Web services, WCF services allow you to create distributed systems using a service-oriented architecture. However, WCF services provide much greater flexibility (such as choice of transport protocol) and additional features (such as transactions and security). WCF is much more than merely an extension of Web services, but if you are new to WCF, initially thinking about WCF services in this way is a reasonable approach. Figure 1 shows a simple but representative WCF scenario. Here Internet Explorer® is acting as a client program and is accessing an ASP.NET Web application that accepts some text from the user and computes a crypto-hash of it. Behind the scenes, the ASP.NET Web app is calling a WCF service to actually perform the hashing computation. In this particular scenario, the WCF service is being hosted by IIS and being consumed by an ASP.NET Web app, but as I will explain shortly, WCF services can be hosted in several ways in addition to IIS and can be consumed by virtually any type of application or other service. The most basic type of WCF service testing involves verifying the functional correctness of the service operations. One approach would be to manually test a WCF service through an application UI. But, although manual testing is necessary, using this approach to test the basic functionality of a WCF service would be time consuming, error prone, inefficient, and just plain boring. A better approach would be to write test automation similar to the program shown running in Figure 2. The screenshot shows a console application test harness I wrote that feeds input text directly to the back-end WCF service, fetches the response message from the service, and determines a pass/fail test case result. The diagram in Figure 3 is a simplified view and summary of the relationships between the programs shown in Figures 1 and 2. In many cases, WCF services retrieve information from a back-end database, or retrieve information from Web services or WCF services, but I have not included those scenarios in Figure 3. Send your questions and comments for James to testrun@microsoft.com. Code download available at msdn.microsoft.com/magazine/cc135911. Figure 1 Typical WCF Application Scenario Next, I’ll explain the back-end WCF service so you’ll understand exactly what is being tested, briefly discuss the ASP.NET Web application shown in Figure 1 which consumes the WCF service, and describe the test harness in detail. I’ll conclude by touching upon some other WCF testing scenarios. Figure 2 Testing a WCF Service July 2008 111 http://msdn.microsoft.com/magazine/cc135911

Table of Contents Feed for the Digital Edition of MSDN Magazine - July 2008

MSDN Magazine - July 2008 Contents Toolbox CLR Inside Out Flex Your Data Data Points Advanced Basics Office Space Cutting Edge Data Services ADO.NET Data and WPF Transactions WCF P2P Test Run Security Briefs Foundations .NET Matters {End Bracket}

MSDN Magazine - July 2008

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