This is a server implementation of the ZeroMQ Gossip Protocol (ZGP)
C:HELLO ( C:PUBLISH / S:PUBLISH / heartbeat )
heartbeat = C:PING / S:PONG
Client says hello to server
Client or server announces a new tuple
Tuple key, globally unique
Tuple value, as printable string
Time to live, msecs
Client signals liveness
Server responds to ping; note that pongs are not correlated with pings,
and may be mixed with other commands, and the client should treat any
incoming traffic as valid activity.
Server rejects command as invalid