Application Center Test (ACT) and the Web Application Stress Tool (WAS) are two tools used to simulate "real world" use of your application. ACT was released with the enterprise versions of Visual Studio .NET 2002 and 2003, while WAS is a free download from Microsoft.

WAS has many admirable qualities, the most prominent of which is that it's free. It's a great tool to create blunt-force traffic simulations against your application. It works by recording your actions in Internet Explorer to create a script that simulates the requests of your browser. This script can be deployed to several machines and coordinated to fire off multiple sessions from each box.

ACT does very much the same thing, but it includes an object model that you can write VBScript and Jscript scripts against. This enables you to tailor the next step in the script depending on the kind of response that you get from the server.

Both applications create reports that tell you how fast the server is responding, how many requests it can handle per second, and so on. These reports give you a good 10,000-foot view of how well your application can respond to heavy traffic. They can isolate problems to single pages or requests, but they don't get to the heart of any underlying problems. You'll need to use other methods in this chapter to get these details.

Both applications have walkthroughs and extensive documentation on

Microsoft is planning to include load testing and unit testing tools in Visual Studio 2005. At the time of this writing, Microsoft has announced Team System, though it has not yet reached beta stage. It is expected to be included only in the enterprise-level versions.

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