One current trend in web development is toward the proper use of REST (Representational State Transfer). Rest maps 4 of the HTTP verbs, GET, POST, PUT and DELETE to Create, Read, Update, and Delete actions within a web application.

Browsers do not have direct support for PUT and DELETE currently, although this is coming when HTML 5 eventually comes out. However, PUT and DELETE are already supported in the XMLHttpRequest implementation in all major browsers, so it is possible create proper REST implementations of Ajax forms. The gotcha in this case is that many load testing tools will have trouble recording PUT or DELETE requests, or problems running them at test-time. For the time being, if you are using Ajax forms, double-check to make sure your requests are properly recorded and replayed.

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Within the previous five years, the size of the average web page has more than tripled, and the number of external objects has nearly doubled. The average page size is currently a little over 300k, according to WebsiteOptimization.com.

There are a number of optimizations that help with larger page sizes.

To take one, example, server-side compression mechanisms provide a good option to negate some of the problems that accompany larger page size, like higher bandwidth costs, and slower page load times.

If your web server is running Apache, mod_deflate can help. If you’re using IIS, there is a good article about compression settings in IIS here.

As with most optimizations, there is a trade-off. In the case of compression, the trade-off comes in higher CPU utilization. A nice overview of compression can be found here. Even though compression raises CPU usage, optimization is a game of trading what you have to spare to get more of what you need, so if you can spare some CPU cycles, compression is a very smart trade.

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Google recently announced a new open source Firefox plugin named Page Speed. Page Speed is an addition to the already amazingly handy Firebug plugin. It provides an additional tab within Firebug that displays information on how to speed up your web page load time.

Google Page Speed Plugin Screenshot

Implementing the optimizations suggested by the Page Speed plugin can help lower your base-line response time. Check it out if you haven’t already!

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If you’re load testing an app with Ajax that uses polling, or comet, using an http level test (no browser), don’t assume you can safely re-use your script in subsequent load tests. If a developer changes the polling interval, your script will no longer be accurate and the load it generates may be substantially less or more intense than real world traffic. A change like this is easy to miss. Also, if you don’t have content-checks on your Ajax actions, other changes may invalidate your script without you ever realizing it.

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