Often application errors do not cause erroneous HTTP responses. Instead, the application responds with incorrect data values or with error messages incorporated in the HTML content, such as A Servlet Exception occurred... or Server Too Busy.... A simple check of the HTTP status code will not uncover this class of errors. Therefore, application errors are often overseen if you do not build additional checks into your test script. Verification functions help you to check for application errors that are not simple, standard HTTP errors.

With verification built into your test scripts, your test evolves from being a simple load test to a becoming a combined load and functionality test. You can use these scripts without major performance penalties, even during large load test scenarios. They will, therefore, be able to detect a new class of application errors—errors which only occur under load, but which would be overlooked by a simple load test script without additional verification checks.

Silk Performer offers three means of enhancing your test scripts with verification functionality: