Command

Signals that the pipeline HeadStage is connected and ready to accept read and write requests

Signals to the tail of the pipeline that it has been disconnected and shutdown. Any following reads or writes will result in an exception, EOF, a general Exception signaling the stage is not connected, or otherwise.

Signals to the entire pipeline that the HeadStage has been disconnected and shutdown. Any following reads or writes will result in an exception, EOF or otherwise