What is "messagepack"

MessagePack is a computer data interchange format. It is a binary form for representing simple data structures like arrays and associative arrays. MessagePack aims to be as compact and simple as possible. The official implementation is available in a variety of languages such as C, C++, C#, D, Erlang, Go, Haskell, Java, JavaScript, Lua, OCaml, Perl, PHP, Python, Ruby, Scala, Smalltalk, and Swift.