rabbitmq user plugin

[AnnMuharram]

Hello, I'm work some with RabbitMQ and now I want to write for my course work the plugin which would log all messages in system.
I try rabbit_exchange_type_recent_history.erl example and also try to understand source code of RabbitMQ. But I can't understand yet how my plugin would receive all messages in system. What should I use for it?

Thanks for your help,
Ann Muharram