Eventlet meets Avro RPC in an unlikely (in my opinion) place: WSGI. Instead of building their own transport layer for RPC calls, Avro sits on top of HTTP for its transport layer, POST’ing binary data to the server and processing the response. Since Avro can sit on top of HTTP, we can use eventlet.wsgi for building a fast, simple RPC server.
I’ve never used Avro before, but its supporters seem to really like it. It seems to have improved upon Protocol Buffers (while preceding them chronologically), and has a very efficient wire encoding.