- What is Correlation?
- Many applications use dynamic values that change each time you use the application.
- For example, some servers assign a unique session ID for every new session. When you try to replay a recorded session, the application creates a new session ID that differs from the recorded session ID.
- LoadRunner addresses this issue through correlation.
- Correlation saves the changing values, in our case the session ID, to a parameter.
- When running the emulation, the Vuser does not use the recorded value—instead; it uses the new session ID, assigned to it by the server.
- Correlation is used when a recorded script includes a dynamic value (such as a session ID) and cannot replay. To resolve this, you make the dynamic value into a variable thereby enabling your script to replay successfully.
- For example, many applications and Web sites identify a session by the current date and time. If you try to replay a script, it will fail because the current time is different than the recorded time. Correlating the data enables you to save the dynamic data and use it throughout the scenario run.
- When a correlation is created, VuGen adds a function that extracts the dynamic value to a parameter. Appropriate occurrences of the original value are replaced with a parameter.
