How DFEs Modify a Vuser Script

Note: This topic applies to Web - HTTP/HTML and Silverlight Vuser scripts, and to Web - HTTP/HTML steps inside Flex Vuser scripts.

When a DFE is applied to a Vuser script and the script is then regenerated, the DFE causes various modifications to be made to the script, as follows:

  • VuGen replaces the original encoded text string with a parameter.
  • VuGen inserts a web_convert_from_formatted function before the function that contains the new parameter. The web_convert_from_formatted function contains the decoded value of the original encoded text.

The script section below shows a web_custom_request function that was generated without DFE support. The Body tag in the function includes a text string that is base64 encoded, Body=TW9uZGF5. Because the value of the Body tag is encoded, it is difficult to change its value if required for correlation or parameterization purposes.

After applying Base64 DFE support, the value of the Body tag in the regenerated script is replaced with a parameter called DFE_PARAM, "Body={DFE_PARAM}, as shown below.

In addition, the modified code also includes a web_convert_from_formatted function. The function indicates that the decoded value of the originally encoded string is Monday. It is now simple to change the value from Monday to any other day by simply changing the decoded value in the web_convert_from_formatted function.

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