This distribution includes the AnyEvent::MessagePack module that would desserve to have its own distribution.
This review is only about AnyEvent::MessagePack.
AnyEvent::MessagePack combined to its underlying engine Data::MessagePack::Stream has currently major design issues that makes it not a 100% clean AnyEvent read_type: it will eat all the data it receives and pass it to Data::MessagePack::Stream, even if not all data is MessagePack. So if your stream combines both MessagePack and other data types (JSON, Storable) at the raw level, don't expect it to work correctly. As Data::MessagePack::Stream 0.07 doesn't have an API to give back the data it didn't consume, this is not fixable.