Text and Image Verification (Web Vuser Scripts) - Overview
Note: Applies to: web Vuser protocols
For a list of web Vuser protocols, see Web Vuser Types.
VuGen enables you to add checks to your web Vuser scripts. A check verifies the presence of a specific object in a web page. The object can be either a text string or an image.
Checks enable you to determine whether or not your website is functioning correctly while it is being accessed by many Vusers—that is, does the server return the correct web pages? This is particularly important while your site is under the load of many users, a period when the server is more likely to return incorrect pages.
For example, assume that your website displays information on the temperatures in major cities around the world. You use VuGen to create a Vuser script that accesses your website.
The Vuser accesses the site and executes a text check on this web page. For example, if the word Temperature appears on the page, the check passes. If Temperature does not appear because, for example, the correct page was not returned by the server, the check fails. Note that the text check step appears before the URL step. This is because VuGen registers, or prepares in advance, the search information relevant for the next step. When you run the Vuser script, VuGen conducts the check on the web page that follows.
Although the server may display the correct page when you record the script and when a single Vuser executes the script, it is possible that the correct page will not be returned when the server is under the load of many Vusers. The server may then be overloaded and may therefore return meaningless or incorrect HTML code. Alternatively, in some instances when a server is overloaded, the server returns a 500 Server Error page. In both of these cases, you can insert a check to determine whether or not the correct page is returned by the server.
Note: Checks increase the work of a Vuser, and therefore you may be able to run fewer Vusers per load generator. You should use checks only where experience has shown that the server sometimes returns an incorrect page.