Why load testing?
In today's world of e-business, your customers and business partners want their Web sites to be competitive. The criteria for a competitive Website are the following : pages that download immediately and efficient and accurate online transactions.
Online consumer and B2B marketplaces are more and more competitive. Companies cannot must be very careful and check the ability of their Web-based applications to accommodate multiple, simultaneous users who are connecting themselves to a Web site or engaging in online transactions. Those enterprises appeal more and more to the purchase of an application load-testing tool.
What is a load testing tool?
The principle of a load-testing tool is to simulate the behaviour of real users with "virtual" users. The load-testing tool can then record the behaviour of the site under the load and give information on the virtual users' experiences.
Load-testing software is often distributive in nature. It is applied on multiple servers running simultaneously, with each server simulating multiple virtual users. In many cases, the testing company has developed its own proprietary browser that can be combined with a set of instructions tailored to the testing of each client business. The testing company maintains ongoing records of the virtual users' experiences at the test site, including response times and errors.
Many testing companies also monitor the client Web site remotely to help diagnose connectivity problems. The actual error messages experienced by the virtual users may be recorded for later review. A set of logs can be created that document each of the user experiences, and this information can later be compared with CPU and database testing information obtained during the test by a systems administrator or by software offered by the testing company.
One feature that load-testing companies often provide is testing the Web-based application externally from multiple points of presence to ensure that the quality of the provider's connectivity isn't the cause of system slowdowns. For example, if the client network was expected to have 10 Mbps of bandwidth but consistently experiences network slowdowns at 6 Mbps, this may signify that the network isn't getting its expected 10 Mbps.
The next advantage of the testing is that it provides information about the performance of the infrastructure of the client network itself. Firewalls, routers and load balancers may all be linked. For instance, a firewall may not have sufficient throughput to stand the number of simultaneous users.
From this point forward, the load testing tool essentially simulates real user activity at the site and focuses more on the performance of the application and the database software under stress.
In July 2002, Amplitude Research made an online survey to get the opinions of technology-sector employees who had experienced Web applications load testing. The 319 respondents came from various professional sectors: CEO, managers, programmers.
Factors for Successful Load Testing
In general, the results of the survey showed positive points of view for the load-testing industry. This survey allows us to summarize what should do a good load testing tool :
- importance on the technical components of load testing (preferring an outsourced test environment)
- Testing at different speeds . It is the only way that allows you to see if slower connections use more resources. This may reduce the number of virtual users who may simultaneously visit a Web site.
- Testing on different browsers . You don’t generally do load testing to check your browser, but it can offer important insight into the error-free performance of Web-based applications on different browsers.
- The ability to do complex scenario to simulate user experiences . To simulate a real user experience, the company that load tests needs to create a scenario where the information to do the test are provided o the testing browsers. This scenario needs to be closely alike the transactions performed by the real users of the Web site.
Our survey results, then indicated that people wanted clear reports that show them errors, time response, all information that help optimizing the performance of the web site.
Given the growing interest of the enterprises for that activity, the report of the testing data should try to be the more concise and easily understandable as possible. As for the testing tool that should be the more user friendly and intuitive as possible so as to facilitate the work of the SI who want to do some load testing.
Customers who were the more satisfied with their load-testing tools were those who thought that their products did not only a good job of predicting real-world performance but also provided easy-to-understand reports. Price was not a significant criterion of satisfaction, nor was the total IT budget of the respondent's company. Overall, individuals currently using load-testing tools placed greater importance on the various activities provided by vendors than did individuals who were not presently conducting load tests.
Conclusion
The first point to check so as to measure the quality of a load testing tool, is its ability to simulate the real user behaviour at your Web site. You must be sure the tool can adapt itself to your needs through relevant scenarios, monitoring and other relevant activities. The more information a load testing tool can accumulate about your Web site and the user experiences, the more likely it is to identify load problems that would affect your end-users.
The last point to check so as to evaluate your load testing tool is the information and advice that are provided at the end of the test. Ask for an example of report so as to see if the information provided are useful for you. Of course be careful to choose an enterprise that has experience in load-testing and that can provide you services and help you if necessary in your load testing project. The recommendations of load testing experts help to optimize the use of the load testing tool.
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