channel.publish() now returns a DeferredConsumer object on which callbacks can be installed for handling returned messages,
channel.get().onSize() has a different behavior: it now reports the message size (and no longer the queue size),
channel.get().onCount() has been added: it reports the queue size (this used to be the onSize() method),
channel.consume().onSize() method has been added to find out the size of the upcoming message
Emiel Bruijntjes