Correlation Using Load Runner - Part1 - Chapter13

• Correlation General Description : Capturing Dynamic values from the preceding requests and substituting in the post request. 
• Example: for every login, you would notice "Welcome Login User". This login user will vary for the next user login. But our script which we recorded will have hard coded value of login user and when replayed it will try to login with same user and same login session. In this case, the existing session has already gone, but our script will try to make a login request with existing session, which make no sense and will return in failed request.
• Hence, correlation concepts helps us in identifying dynamic values, especially dynamic session ids, and will handle, so that the every requests, goes with updated or latest values returned from server.
• As a beginner, To identify dynamic values in the newly captured, we need to record same flow twice a time compare line by line and should trace the difference.
• Once the changes in values are identified, we need to take that dynamic value and should go to Generation Log(Output Pane-->Replay Drop down-->Code Generation). 
• Once Generation log is opened,Ctrl+home and search for the dynamic value occurrence.
• We should search the dynamic value and trace out that the dynamic value should be found in the response header.
• Once the dynamic value is found in the first response header, search for "add event", which is a key to identify on which particular request, this dynamic value is triggered from server.
• Once the request url is identified, go to script Action part--> search for the request name, and on the above the request name, we need to add correlation function "web_reg_save_param".
• Stay tuned for more learnings.