Build custom protocols with Ranch and msgpack

Building protocols is fun!

Loïc Hoguin - @lhoguin

Erlang Cowboy and Nine Nines Founder

Essentials

Ranch

• Spin-off from Cowboy
• Transport and protocol agnostic acceptor pool
• Fully dynamic
• Well documented
• Production ready
• Tested with > 1 million Websocket connections

msgpack 1/2

• "It's like JSON. but fast and small."
• Binary serialization library
• Deserialization is streamable
• http://msgpack.org

msgpack 2/2

• Available for Ruby, Python, Perl, C/C++, Java, Scala, PHP, Lua, JavaScript, Node.js, Haskell, C#, Objective-C, Erlang, D, OCaml, Go, LabVIEW, Smalltalk

Using msgpack with Ranch

• PASTE LIVE DEMO HERE

Guide to building a msgpack RPC service

• You most likely won't need async, sync is easier to pull off
• You most likely don't need connection pooling
• Follow the HTTP request/response model
• Send a request, expect a response, continue if successful
• Don't forget to close the connection when done

The future of Ranch

Custom connections supervisor

• Remove the need to monitor processes twice
• Reduce the overhead to a minimal
• No gen.erl, gen_server.erl
• No options to take care of, no restart strategy
• Bare minimum

Minimal supervisor

• Special process
• Traps exits
• Exit when parent exits
• Handle '$gen_call' messages
• Reply properly to which_children message

Results

• About 100LOCs for the supervisor
• Greatly simplified architecture of the project
• Much improved performance, especially with many connections
• Still OTP

Thanks!

• http://ninenines.eu
• https://github.com/extend/ranch
• #ninenines on Freenode
• @lhoguin on Twitter

Questions?