Link transformer and appsink plugins

I have developed a gstreamer plugin based on GstBaseTransform. It receives portions of data, transform them and push bufer further.
In my application I created pipeline with appsink plugin, something like that:
and then I request data with:
but it dont receive any samples and pipeline stops.
What methods should be implemented to make communication working?
Or maybe you can show me working example.

Why does the pipeline stop? How do you know that it stopped? Did you start the pipeline? (i.e. set it to PLAYING state)

Just to be sure, pull_sample() doesn’t “request data”, i.e. it doesn’t make anything happen that wouldn’t happen without it. It just waits for data to arrive at the sink from one of the streaming threads (src/transform/queue, here: queue source pad thread).

So if you’re not getting data in pull_sample() it’s likely either because you didn’t set the pipeline to PLAYING state, or an error occured (are you checking the pipeline’s bus for error messages?), or no data is making it through to the sink (check the debug logs to see if the source outputs data, and if the transform element outputs data).