Hello! I have a dataflow pipeline built using Flink's RichParallelSourceFunction as parallel sources. I'm wondering if there are any mechanisms that I could use to implement *ack-based* back-pressure mechanism by sending ACK messages from operators (within the runtime) to source functions to achieve user-level back-pressure mechanisms? I understand that Flink uses flow control to perform back pressure internally but I'd like to check whether it is possible at all to send any events from operator to sources.
Thanks in advance! Le
