Digging a lil' bit inside the supported transports (Netty/InVm), I've found what I suspect could be an interesting and useful other transport: inter process using virtual memory.
Using "pipes" implemented on memory mapped files it could be possible to have a client inside a Docker container and the broker running in another one on the same machine, allowing the two to communicate without using any network stack (with no need to use SSL or other security layers too).
This will work inside the same process between different threads and in the same OS between different processes too: it could be possible to have an IPC pipe built on top of memory mapped files capable to push about ~450 M msg/sec on a simple laptop, hence far beyond any network layer capacity or any need of a broker transport.
wdyt? it could be of any use?