To correlate the access token, you can use the following
- 
                     a Regular Expression Extractor that saves the access token into a local variable 
- 
                     a BeanShell Sampler that calls the "setProperty" function to set the local variable as a global property, so that it can be shared in all thread groups 
In the case of PowerServer, the GetToken request gets the access token, therefore, you add a Regular Expression Extractor to the GetToken request to get and save the token into a local variable.
A GetToken request will look like this:

To add a Regular Expression Extractor, right click on the GetToken request and then select Add > Post Processors > Regular Expression Extractor.
Specify the Regular Expression Extractor like this.
- 
                     Name of created variable: "token" or any name you prefer 
- 
                     Regular Expression: "access_token":"(.+?)" 
- 
                     Template: $1$ 
- 
                     Match No.: 1 
The access token will be saved to the "token"
                         variable. You can invoke the local variable by typing
                         ${token} in the requests (bodies and headers).
            

If you want to make the "token" variable a global
                         property that can be accessed by all threads and thread groups, you
                         can add a BeanShell Sampler or
                         BeanShell PostProcessor to call the
                         JMeter "setProperty" function. The "setProperty" function can set
                         the "token" variable as a global property. the section called “Modifying scripts” has instructions for how to add
                         a BeanShell PostProcessor. This
                         section will show how to add a BeanShell
                               Sampler.
            
To add a BeanShell Sampler, right click on setUp Thread Group, and then select Add > Sampler > BeanShell Sampler.
- 
                     Use the default name or input any name you prefer. 
- 
                     Input the following script: ${__setProperty(token,${token},)}
The "token" variable can be accessed as a JMeter
                         global property.
            

Find the access token in all thread groups, and replace the
                         static value of token with the global property
                         ${__property(token,,)}.
            


