Parasoft's Brunell on SOAP implementation issues
- By Jack Vaughan
It is early in Web services implementation, but not too early to begin worrying about how Web services will hold up under load and stress. Thus, test companies such as Parasoft have entered the fray.
In Web services, XML is used via SOAP to describe software as a service. Sometimes the underlying framework resides on Java; sometimes, it may reside on .NET or other architectures. That's a vast simplification, of course, as making Web services work in practice is no small task. Yet Web services are not entirely unfamiliar.
"Web services, in general, are taking and building on a concept that has been around for a long time, which is exposing things and allowing shared access," said Gary Brunell, vice president of professional services at Parasoft. "The problem with Web services is that there are many different touch points in the life of a transaction from the time of a request to the time of a response. And throughout, there is a lot of room for error," he explained.
And since it is early in the game, there are some compatibility issues as well, Brunell added.
Protocol mismatches today are the toughest errors to find, noted Brunell, and, as in other computing environments, when a service fails there is usually some finger pointing between operations and development teams. Tools like Parasoft's can alleviate some of this.
"An example of protocol problems occurs sometimes when people rely on tools to auto-generate WSDL," said Brunell. While these tools may appear to be working, they can create protocol mismatches. "[Parasoft's] SoapTest software can span down to highlight the line [that marks the problem]," he said.
"Other times, we are seeing errors in implementation -- for example, how SOAP servers are being handled," commented Brunell. "Without a tester, you have to go through a systematic stubbing process to find the root problem."
After developers do achieve functionality, they then have to try to see what load their Web service will sustain.
Developers are beginning to use products such as Parasoft SoapTest to view application behavior from a load and regression point of view "to see, for example, how many purchase orders the Web service can handle in an hour," said Brunell.
"We have consultants using it in a lot of areas, and each has a different motivation -- how well built it is, how well the Web service is running or, if I am changing the nature of a service, how an application keeps pace with that," he explained.
Many of the apps now being re-deployed as Web services must be able to maintain established Service-Level Agreements, he said. Regression testing will increasingly be used to make sure that as development teams go through multiple iterations and interactions, that the timing on these Web services is good and that the service itself has not been altered in any way.
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Jack Vaughan is former Editor-at-Large at Application Development Trends magazine.