APM parse HTTP Connector json to message box, iRule etc.

Hello all,

I have configured per-session and per-request policies on my APM (APM+LTM) mode and in the process of authentication I want to get some data from external web server. Data is in JSON format. To do that I have created HTTP Connector, assigned it to my per-request policy via subroutine and i can see that the subsession variables are beeing populated correctly via the HTTP Connector (with option save data, i can parse it but the result is the same, just more variables - one per JSON field). In the Overview:Active Session i can see subsession with the following variable with my data:

879cb369./Common/HTTPConnector/XXXXXXXXXXX==.nvp_block.subsession.http_connector.body

Now I wanted to get this data and use it in my authentication flow and iRule but it doesn't work.

First I wanted to test it, by assiginig variable and showing a simple message box in PerReq-policy:

And after that the massage box with: %{perflow.custom} - it doesnt work.

Also tried to just show it in logs with iRule like in documentation ltm rule command ACCESS perflow (f5.com)

So i created an iRule agent in per-request-policy pointing to bellow iRule and attached iRule to my VS:

when ACCESS_PER_REQUEST_AGENT_EVENT {

set $body [ACCESS::perflow get subsession.http_connector.body]

log local0. $body

}

But it doesnt show anything.

I have few questions:

1. Is it even possible to access variables in subsession that got retrieved via HTTPConnector and use it further? For example to build JWT for auth?
2. Can I assign more than two custom variables from subsession? according to this guide i can only use perflow.custom and perflow.scratchpad?:
   Using Variable Assign to populate gating criteria,Using Variable Assign to populate gating criteria,Using Variable Assign to populate gating criteria (f5.com)

Using Variable Assign to populate a perflow variable other than perflow.custom and perflow.scratchpad causes subroutine results to become unreliable.

3. Maybe there is an other option to achieve my goal?