NATS[1] is a relatively simple pub-sub protocol and broker created by Derek Collison. It's originally written in Ruby. It was created as the messaging layer of

NATS[1] is a relatively simple pub-sub protocol and broker created by Derek Collison. It's originally written in Ruby. It was created as the messaging layer of Cloud Foundry. From the technical side - routing is done using regular expressions, the speed of internal routing is proportional to number of different subscriptions. Additionally, NATS have some interesting specific features - for example: if I remember correctly messages for slow consumers are just dropped. NATS was originally a monolithic server, but I see that some work on clustering had been done [2]. [1] https://github.com/derekcollison/nats https://github.com/derekcollison/nats [2] https://github.com/derekcollison/nats/wiki/Cluster-Design https://github.com/derekcollison/nats/wiki/Cluster-Design