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From Scott Dean <>
Subject Re: [OpenIV:0551] Re: Bugzilla Enhancement: "Auto-Correlation as core functionality in JMeter"
Date Tue, 26 Nov 2019 18:46:35 GMT

I am not part of this project to add auto-correlation to JMeter but here is
my take on it:

(Note: I use the words "script" and "test plan" interchangeably)

Correlation is the process of capturing the session-specific information
passed from server to client and back to server for purposes of maintaining
state, etc in http interactions.

Manual correlation is where the person(s) developing the JMeter test plan
manually identify the parameter(s) that needs to be captured, find where
the values of those parameters were initially introduced in the script,
inserts the appropriate extractors to capture the values, then replaces the
recorded values with the JMeter variables used to hold the extracted values.

Auto-correlation is doing this process programmatically.

In general, auto-correlation is done one of two ways:

   - *Two Scripts*: Record the same sequence of actions twice then run a
   comparison of the two recordings (.jmx files) and look for where data and
   parameters differ.  Ignoring differences that are generally irrelevant,
   like timestamps, present those differences to the JMeter user, allowing
   each difference to be accepted or ignored by the user.  For accepted
   differences, automatically insert a relevant extractor at the relevant
   place and search/replace the recorded value with the JMeter variable used
   in relevant extraction.  These steps are performed on one of the recorded
   scripts, generally the initial recorded script;  the other recorded script
   is generally discarded after the process is complete.

   - *Rules*: Using rules that define the names of parameters that need to
   be captured and how to capture them, these rules are applied to a test
   plan.  Based on criteria specified in the rule, the test plan is analyzed,
   rule matches identified, extractors insert, and hard-coded parameter values
   replaced with JMeter variables holding the extracted values

I will stop here.

As I said, this is my understanding of the process and may or may not be
exactly the processes/methods used in the proposed enhancement.  Feel free
to correct me.

Hope that helps!

-- Scott Dean
   North Carolina State University
   Raleigh, NC   USA

On Tue, Nov 26, 2019 at 5:53 AM Vladimir Sitnikov <> wrote:

> >About new feature of auto-correlation, we prepared specification written
> as manual.
> That is great. It really helps to preview the feature.
> However, I fail to understand what is "correlation with JMX file".
> I see it consumes an extra JMX file, but it is not clear what should be
> there in the file,
> it is not clear what is added as a result.
> Does "Correlation" differ from "Auto-Correlation"? Should just one of them
> be used in all the places?
> Is there a "manual correlation"?
> How Rule differs from Correlation?
> Is Rule mandatory for Correlation to work?
> Vladimir

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