Answer / shivakumar

Hi chandana

correlation is very simple, it means to capture the dynamic
values which are sent from the server. rules in the sense,
this procedure we hve to follow for doing correlation in a
simple manner.

stepl:- generate the two scripts for the same actions;

2) then you hve to compare the two scripts by using wdiff
tool, it is a part of vugen component.

3)identify the dynamic values which are different from each
other like transaction id's and session id's etc.

4)copy the value which you would like to correlate and find
out in the script and go to tree view, check the value in
the server response. ctrl+f

5)by using this function
web_reg_save_param("parameter_name","LB='some
value'","RB='some value'","ord='number'","Last");

6)Enable the extended logs in the runtime settings(VUGen)
and click the parameter substitution.

7) compile and run...

8) check the values in the output window wheather it is
sucessfully or not. the line will be appeared in blue colour.

Answer / srinivas

To answer Naga first, i think what he wrote <may not be
meaning> about is Auto Correlation rules that are found in
Recording options at the last tab
<In case if it is being misunderstood; just to avoid
exploration in wrong direction>.

Assuming it to be normal correlation of dynamic values
sought by server, for session authentication and validation.

Here what you can try is, after recording, check for
recording / replay log<detailed>, where you can search
common data chunks between certain response and subsequent
request. IF there is something common, it means that value
which was returned in the respnse was expected ny the
server in consequent request.
>> Inferrence this peice was candidate for correlation.

Answer / rani

Correlation means capturing a dynamic value which is
generated from the server. you can clearly know these
values by seeing your script as they looks like a strange
values. After running the script in the extended log,You
can search the name of the value in the execution log and
find out the left and right boundary and include the
web_reg_save_param function in your script before the
dynamic value and then parameterize the dynamic value in
your script by deleting the dynamic value and give a name
enclosed in clurly braces to the dynamic value. Then run
your script. your script should pass if you mention correct
right and left boundaries.

Answer / gopi

if u wnat find Correlation values just record the script
twice and compare them from comparision u came to know what
are the dynamic values in ur script.other wise u can use
beyond compare s/w u can compare bothe of the scripts.

if u use .net(my application) based application these type
of dynamic values u will get
28. VsKey Correlation Path : web_reg_save_param
("vskey1","LB=__vsKey\" value=\"","RB=\"",LAST);
29. ViewState Correlation : web_reg_save_param
("viewstate1","LB=__VIEWSTATE\" value=\"","RB=\"",Last);
30. Event Validation Path : web_reg_save_param
("evehan1","LB=__EVENTVALIDATION\" value=\"","RB=\"",LAST);
31. Control ID path : web_reg_save_param
("ControlId","LB=ControlID=","RB=&",LAST);
32. Report Session ID : web_reg_save_param
("ReportSessionId","LB=ReportSession=","RB=&",LAST);
33. Session ID Path : web_reg_save_param
("SessionId","LB=Search in general log","RB=Search in
general log",LAST);

Answer / yugender

http://motevich.blogspot.com/ With using this URL, u have a
good clarity on correlation..

Answer / bhanu pratap singh

If you try to replay a script without correlating first,
then most likely the script will fail. The requests it
sends to the server will not be replied to. Either the
session ID is invalid, so the server won’t allow you into
the site, or it won’t allow you to create new records
because they are the same as existing ones, or the server
won’t understand your request because it isn’t what it is
expecting.



Any value which changes every time you connect to the
server is a candidate for correlation. A correlated script
will send the server the information it is looking for, and
so allow the script to replay. This will allow many Vusers
to replay the script many times, and so place load on your
server.

Answer / naga

Rules in the sense.Did not get your question..See
correlation comes into picture for dynamic values which are
returned from the server.. Common Dynamic values being
Session Id, Account number which is generated on filling a
bank account opening form, Transaction Id etc..

Answer / chandana

Thank u Mr Naga,

suppose i am testing a telecom domine project,so
how can i find the correlated values,

as my knowledge correlated value is nothing but a
uniq key elements right(witch is not duplicate)

Answer / naga

I believe Correlation is a hot and very important topic in
Load Runner which is asked in every Performance Testing
interview.

Srinivas I did not undertand what you are trying to anser
me. I have quoted the examples based on the work I do.
Generally we correlate the account number, trasaction id as
I am from a Banking Domain. Chandana wherther you are
working on a Telecom or from any background..it doesnt
matter Correlation is used for any dynamic data which is
sent from server.

Automatic correalation is not useful always there are some
dynamic values which automatic correlation can detect. For
this reason it is preferred to go with manual correlation
which Rani has explained.

For a better understanding you can check the following link
which has a very good explaination about correlation:

http://motevich.blogspot.com/2007/10/loadrunner-scripts-
correlation-tutorial.html

Answer / bhanu pratap singh

http://www.allinterview.com/showanswers/56961.html With
using this URL, u have a
good clarity on correlation..

how can u capture the database counters?

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