...

• --consumer-rebalance-listener - to allow user to wire in a custom rebalance listener which implements ConusmerRebalanceCallback interface. An internal rebalance listener which implements ConsumerRebalanceCallback is wired in by default to avoid duplicates on consumer rebalance. User could still specify a custom listener class in command line argument. The internal rebalance listener will call that custom listener after it finishes the default logic.
• --consumer-rebalance-listener-args - to provide arguments to custom rebalance listener constructor.
• --message-handler - to allow user do some simple process on the messages (e.g. filtering, reformatting, etc)
• --message-handler-args - to provide arguments for message handler init() function.
• --abort-on-send-fail - define whether mirror maker should abort when a send failed(turned on by default)
• Change all the other options to unix like option, i.e. replacing dot with dash.

Proposed Changes

• Each mirror maker thread consume messages, process them and then send them.
• Scale by creating more mirror maker thread.

...