Correlation in Jmeter

To remove the dynamic value of Http request correlation is used .Jmeter Script can be correlated with help of Regular expression Extractor .

I have Recorded the login action of IRCTC Website   and  Correlated  the  Session_ID and Engine_ID

Refer the Screenshot below to view the Dynamic  Session_ID and Engine_ID

https://www.irctc.co.in/cgi-bin/bv60.dll/irctc/booking/planner.do?screen=fromlogin&
BV_SessionID=   @@@@1502947175.1355111858@@@@                        &
 {Left Boundary }        Dynamic Value                                               { Right Boundary}

Steps  of Correlation :

1. Find the Dynamic Value in Http Request in this case  Session_ID and Engine_ID are Dynamic values
2. Add Regular expression Extractor for Seesion_ID  e.g : BV_SessionID=(.*?)&     check  number of occurrences in  Regular expression  tester     
3. Add Regular expression Extractor for BV_EngineID  e.g : BV_EngineID=(.+)">     check  number of occurrences in  Regular expression  tester 

   4. Provide the Template and Match No e.g for First match $1$ and 1 
   5. Replace BV_SessionID and  BV_EngineID values with Variable ${S} and ${E}
Refer the screen Shot Below