Data correlation overview

A request to a Web server can include response data from a previous request. The term we use for this type of association is data correlation. Another commonly used synonymous term is dynamic data.

Interactions with an application are typically interrelated with one another. Specifically, a request made to a Web server frequently includes data that was returned to the Web browser in the response to a previous request. For example, consider the following interaction with a Web-based application: In this example, request 2 is dependent on request 1 and request 3 is dependent on requests 1 and 2.

If you recorded these interactions in a performance test, prior to running the test with multiple users, you would likely vary the test data: substitute the user name/password values, the employee name search values, or both, with values contained in datapools. When you ran the test, each test user would return a different employee payroll record, based on the contents of the datapool(s).

In a generated performance test, where data in a request is dependent on data contained in the response to a previous request, the request data is substituted from the response data on which it depends. The term for this internal tagging of response and request data is data correlation (or, sometimes, dynamic data). Data correlation is required for correct multiuser test execution with varied data.

A reference is a value in a test (usually in a response) that can be used by a subsequent value (usually in a request) in the test. When the test generator detects that a request value should be substituted from a previous value, it designates the earlier value as a reference and correlates the subsequent request value with the reference. This is referred to as automated data correlation. But you can manually correlate any two values in a test or unlink existing correlations. (You can also modify or disable automated data correlation in the preference settings: click Window > Preferences, expand Test, and click Performance Test Generator.

To help you work with correlated data, the test editor uses color coding and provides navigational aids:

Parent topic: Correlating response and request data in a test

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