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This article was originally published in the Summer 2003 issue of Methods & Tools

Modeling the Real World for Load Testing Web Sites - Page 3

Steven Splaine, www.splaine.net

8. Background Noise

Unless the production servers and network are going to be dedicated to supporting the Web site, you should ensure that the servers and network in the system test environment are loaded with appropriate background tasks. When designing a load to test the performance of a Web site or application, consider what additional activities need to be added to a test environment to accurately reflect the performance degradation caused by "background noise." Background noise is created by other applications running that will also be running on the production servers once the application under test moves into production, and other network traffic that will consume network bandwidth and possibly increase the collision rate of the data packets being transmitted over the LAN and/or WAN.

9. User Geographic Locations

Due to network topologies, response times for Web sites vary around the country and around the world. Internet response times can vary from city to city depending on the time of day, the geographic distance between the client and the host Web site, and the local network capacities at the client-side. Remote performance testing can become particularly important if mirror sites are to be strategically positioned in order to improve response times for distant locations.

But how can you effectively test the performance of your Web site from locations that are thousands of miles away? Possible solutions include

• using the services of a third-party company that specializes in testing a Web site from different locations around the world
• utilizing the different physical locations (branches) that your organization may already possess, coordinating the execution of your test plan with coworkers at the offices
• using a modem to dial ISP telephone numbers in different cities and factoring out the additional time for the cross-country modem connection
• buy an "around the world" airplane ticket for one or more of the Web site’s testers

Getting the Right Mix

When developing the load profile that will be used for performance testing, try to take into account as many of the previously mentioned parameters as possible. While a single parameter may only affect the test results by a few percent, the accumulation of several parameters may add up and have a significant impact of the test results.

Credit

This article is drawn from The Web Testing Handbook by Steve Splaine & Stefan Jaskiel (amazon.com) and from SQE’s Web Performance & Security Testing training course (sqe.com). The article is also available for download at stickyminds.com.

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