InformationWeek
Defining The Business Value Of Technology
January 17, 2000
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Is Your Web Site Scalable Enough?
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At about a quarter of the price of the other tested products, RadView's WebLoad 3.51 is the least-expensive entry in this field, but it's also the least powerful. Manual editing of the scripts is required to handle session IDs as well as most functional testing chores.
Unlike the other two products, though, WebLoad uses standard JavaScript for its test scripts and plays back the scripts verbatim. This means you have a lot of direct control over script execution, provided you don't mind editing JavaScript. WebLoad doesn't offer a thick client mode. It uses a minimal HTTP recorder approach which means that it can generate a lot of virtual users using few resources, but, as mentioned earlier, it's also missing a lot of features such as extensive data validation. A new "table compare" feature will check returned table data that you select, but any other validation tasks have to be coded manually in JavaScript.
If these drawbacks don't bother you, WebLoad has an intuitive interface that makes short work of blasting your Web application with traffic and getting results quickly. We especially liked the "goals definition" wizard, which lets you spell out performance goals such as "quit when overall response time is greater than three seconds."
Like e-Load, RadView's controller software runs under Windows 95 and 98, as well as Windows NT 4.0. WebLoad is the only one of the three tested products that will use a machine other than Windows NT for load generation; software that lets you run virtual users remotely on a Sun Solaris system is included.
The Solaris load generator takes about two minutes to install and is completely transparent in distributed load-testing scenarios. Sites with powerful Sparc systems will benefit from offloading virtual users.
Astra LoadTest 3.0
Mercury Interactive's Astra LoadTest 3.0 required the least manual intervention of the three products, rarely requiring direct interaction with the scripts. LoadTest uses a hybrid of stored parameters and VBScript to encode its workload scripts. The VBScript can be directly edited, but the alternative graphical user interface view of the script is more useful.
We especially like LoadTest's reporting capabilities with lots of built-in charting choices and cooperation with Excel. LoadTest is a competent testing tool, but its heavy reliance on the Internet Explorer 5.0 browser made it cumbersome to use at times.
LoadTest's default thick client is made possible by Microsoft's COM/ DCOM technology. LoadTest deploys the Internet Explorer browser as a scriptable memory-resident Component Object Model object, giving the virtual users full access to the features of Internet Explorer 5. On the plus side, this means that things such as session IDs and downloaded ActiveX controls are handled transparently. However, it also means LoadTest is heavily dependent on NT 4.0 (it will be hard to move its workload generator to non-Microsoft platforms). Also, we found the Internet Explorer COM object to be a resource hog. Besides requiring about 12 Mbytes of RAM plus about 200 Kbytes per additional virtual user instance, we were easily able to max out the dual CPUs on the load-generation system with only 20 virtual users.
Notably, Mercury suggests moving to its high-end LoadRunner application ($95,000 for 1,000 virtual client licenses), if you want to run more than 250 virtual clients with Astra.
The application broke when we moved to the Internet Explorer 5.01 update, but Mercury has posted a service pack, SP1, that fixes the problem and adds some new features, such as a minimal HTTP recorder mode. The HTTP recorder mode will be useful for customers who want to blast their Web applications with a minimal virtual user client, but a thicker client, such as the thin client in RSW's e-Load, would require fewer system resources but still handle the complex client-side interactions.
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