What is correlation? Explain the difference between
automatic correlation and manual correlation?
Answer Posted / smita
Correlation is where the script is modified so that some of
the hard-coded values in the script are no longer
hard-coded. Rather then sending the original value to the
server, we may need to send different values.
For example, the original recorded script may have included
the server sending the client a session identification
number, something to identify the client during that
particular session. This Session ID was hard-coded into the
script during recording.
During replay, the server will send the client a new Session
ID. You need to capture this value, and incorporate it into
the script so you can send it back to the server to
correctly identify yourself for this new session. If you
leave the script unmodified, you will send the old
hard-coded Session ID to the server. The server will look
at it and think it invalid or unknown, and so will not send
the pages that have been requested. Replaying a script with
an old Session ID will not successfully fool the server into
believing it is a client.
Correlation is the capturing of dynamic values passed from
the server to the client and back. You save this captured
value into a parameter, and then use this parameter in the
script in place of the original value. During replay, the
replay engine will now listen to what the server sends to
it, and when it makes requests of the server, send this new,
valid value back to the server; thus fooling the server into
believing it is talking to a real client.
Steps to Perform Manual Correlation
1.Record two copies of the script with the same business
process and data:
2.Record a script on the desired business process and save it.
3.Record another copy of the script, repeating all the steps
as in step 1a. As much as possible, during recording, enter
the same values in both scripts, for example, user ID,
password, and fields and edit selections.
4.Identify the values to correlate with the help of the
WinDiff tool:
5.From the second script, go to Tools  Compare with Vuser,
and choose the first recorded script.
6.WinDiff will open and display the two scripts side by
side. It will automatically highlight the lines with
differences in them, showing the differences in red. (If
not, go to Options  View  Show inline differences.)
Tips: Error: "File no longer available." launching WinDiff
7.Locate the first difference, take note of it, and search
the script open in VuGen for that difference. That is the
original value hard-coded into the script that was different
in the second script. Highlight it and copy it.
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