downstream processor
trigger flow control. Should be bigger than maxPendingMessageCountPerAckRequest
send on AckRequest to the target
Handles acknowledge message.
Handles acknowledge message. Throw MessageLossException if required.
acknowledge message received
Returns how many message is actually sent by this subscription
Returns how many message is actually sent by this subscription
the message to send
the target partition to send message to
1 if success
Manges the output and message clock for single downstream processor