Testing the Performance of an IIS Application

An IIS Web application can be written using code optimization techniques, debugged at compile time and run time, configured in IIS to run as fast as possible, and have its security tested by a hacker friend, but there is no way to manually test the way a Web application performs under the stress of hundreds of users until it is deployed on a public Web server. However, there are some tools that can help.

Web Application Stress Tool

The Microsoft Web stress tool is designed to realistically simulate multiple browsers requesting pages from a Web site. The Microsoft WAS Web stress tool is designed to realistically simulate multiple browsers requesting pages from a Web site. You can use this tool to gather performance and stability information about your Web application. This tool simulates a large number of requests with a relatively small number of client machines. The goal is to create an environment that is as close to production as possible so that you can find and eliminate problems in the Web application prior to deployment.

The Web Application Stress Tool was originally developed for Microsoft Application Center under the name Homer.

For more information about the Web Application Stress tool including how to use it and a download location, see Performance Testing with the Web Application Stress Tool

Web Capacity Analysis Tool

The Web Capacity Analysis Tool (WCAT) version 5.2 runs simulated workloads on client/server configurations. You can use WCAT to test how your server running Internet Information Services (IIS) 6.0 and your network configuration respond to a variety of client requests for content, data, or Web pages. You can use the test results to determine the optimal server and network configuration for your environment.

WCAT is a powerful tool for capacity testing and planning. You can use it to test different server and network configurations by using custom designed WCAT content and workload simulations. WCat tests simulate the activity of a server running IIS and its client Web browsers as they communicate across one or more networks. The tool monitors how the server responds to the demands of its clients in a controlled, experimental setting. When you change your hardware and software configuration, you can repeat the prepared tests to identify how the new configuration affects server response to the simulated client workload. You can use WCAT to test servers with single or multiple processors and servers that are connected to multiple networks. In addition, you can use cookies with WCAT. Cookies allow a server or script to maintain state information on client computers.

The Web Capacity Analysis Tool is available in the IIS 6.0 Resource Kit Tools. It can run on Windows 2000 and later.


WFetch version 1.3 is an Hypertext Transfer Protocol (HTTP) client with a graphical interface for testing or troubleshooting HTTP servers. It does not render the HTTP response as most HTTP clients do; instead, it displays the request and response so that the communication can be easily understood. You can use WFetch to create HTTP requests that test the performance of new Web sites or of Web sites that contain new elements, such as Active Server Pages (ASP) or wireless protocols. Because WFetch provides only HTTP connection information, it is a faster way to analyze and troubleshoot HTTP performance than running a NetMon trace.

WFetch supports all common authentication methods: Anonymous, Basic, NTLM, Digest, Kerberos, and Negotiate. In addition, the tool allows you to use secure connections, including the option to choose a secure protocol and cipher. WFetch also supports proxy connections.

WFtech is available in the IIS 6.0 Resource Kit Tools. It can run on Windows 2003 and later.