Correlation in LoadRunner:

VUGen Correlation Tutorial Summary:

• Correlation is done for the dynamic value or the value returned by server for any request.
• Parameterization differs from correlation in a way that former takes care of user input data whereas later takes care of data returned by server.
• Manual correlation and automated correlation follow the same steps.
• In Manual Correlation, we have to identify the dynamic value and capture it from the response of previous request.  Replace dynamic value with parameter name manually everywhere in the script.
• Automated Correlation works with existing rules.
• WDiff is used to identify the dynamic value. With WDiff compare two scripts with identical steps and user input.
• WDiff does line by line comparison.  Another tool available can also be used for word by word comparison.
• Correlation function web_reg_save_param is used for capturing the value for correlation. The other versions of correlation are web_reg_save_param_ex and web_reg_save_param_regexp.
• The mandatory attributes of correlation function web_reg_save_param are parameter name, left boundary (LB) and right boundary (RB).
• Correlation is not only done for dynamic values which change every time but also for data returned by server for different users. To identify such data record, use two scripts with different users (login credentials) keeping user input and steps same. Compare these scripts either with WDiff or any text comparison tool.