Building Web applications has now become a fairly common scenario for developers building new applications or updating and Web enabling existing applications. As applications move to the Web into a server based environment it becomes increasingly important to be able to gauge the performance and load capability of an application. Developers must be able to answer hard questions about how much traffic a given site will be able to handle and make intelligent choices of hardware, software and often times even design approach of the application to make sure the application will be able to handle an onslaught of customers on the Web site. We should all be so lucky to have to worry about the problem of being too successful!

        But it's often surprising to find how many Web sites hit their limits and catch the operators off guard. An overloaded Web site is a major problem and once happening the problem often can't be addressed rapidly. A quick fix typically involves adding additional hardware that must be purchased, installed and configured – a process that may take days or even weeks. Being prepared and understanding the limits of an application and managing advertising to bring traffic to a site in measured spurts is crucial to the success of large and even not so large commercial sites.

        Additionally, it's important to understand that today's tools often make it much easier to build Web applications than the tools from even a year ago. Today we have powerful scripting engines, easy access to COM components we can write in high level languages and Web servers that self-configure for the most part. But along with the ease of use also comes more overhead and resource load on the server and it becomes even more important to look at load issues right from the start of application development. Load testing should be performed in the initial design phases to get a good idea what overhead the application components incur on the server. Constant monitoring should be performed as development continues on always keeping a close eye on how well the software platform in relation to the hardware it will be running on.

        The problem is that often times these scalability questions such as 'How much traffic can we handle on our particular hardware?' are not easily answered because it’s hard to measure performance of Web applications outside the actual environment that they will be running in. Even the process of testing Web applications seems daunting: There are so many pieces involved from a Web browser client, the Web server, the backend application and the backend database server. The bottom line is that the only way to realistically test the load capabilities of a Web application is in a close approximation of a live environment, which means actually 'running' the Web application.