JOLT Guide for Apache NiFi

[#1]

Hi everyone, I hope you’re doing well. I am working on a dataflow in Apache NiFi 1.18, and I need to retrieve the queue size information (flowfile count and content size) directly within NiFi itself, not via an external script or Postman. I know that the NiFi REST API provides this data, and I can access it successfully using external tools. However, my goal is to access queue metrics from inside NiFi, for example through processors like InvokeScriptedProcessor, QueryNiFiReportingTask, or any other built-in mechanism, without sending an external REST API request from outside NiFi. Is there a recommended approach, processor, or reporting task that allows NiFi to read its own queue sizes internally? If not, what would be the best practice to achieve this? Any guidance or examples would be greatly appreciated. Thank you in advance!