RMP - Rust MessagePack

RMP is a pure Rust MessagePack implementation.

• API documentation

• Crates.io

Usage

To use rmp, first add this to your Cargo.toml:

[dependencies.rmp]
rmp = "0.6.0"

Then, add this to your crate root:

extern crate rmp as msgpack;

Features

• Convenient API

RMP is designed to be lightweight and straightforward. There are low-level API, which gives you full control on data encoding/decoding process and makes no heap allocations. On the other hand there are high-level API, which provides you convenient interface using Rust standard library and compiler reflection, allowing to encode/decode structures using derive attribute.

• Zero-copy value decoding

RMP allows to decode bytes from a buffer in a zero-copy manner easily and blazingly fast, while Rust static checks guarantees that the data will be valid until buffer lives.

• Clear error handling

RMP's error system guarantees that you never receive an error enum with unreachable variant.

• Robust and tested

This project is developed using TDD and CI, so any found bugs will be fixed without breaking existing functionality.

Examples

Let's try to encode a tuple of int and string.

extern crate rmp as msgpack;
extern crate rustc_serialize;

use rustc_serialize::Encodable;
use msgpack::Encoder;

fn main() {
    let val = (42u8, "the Answer");

    // The encoder borrows the bytearray buffer.
    let mut buf = [0u8; 13];

    val.encode(&mut Encoder::new(&mut &mut buf[..]));

    assert_eq!([0x92, 0x2a, 0xaa, 0x74, 0x68, 0x65, 0x20, 0x41, 0x6e, 0x73, 0x77, 0x65, 0x72], buf);
}

Now we have an encoded buffer, which we can decode the same way:

extern crate rmp as msgpack;
extern crate rustc_serialize;

use rustc_serialize::Decodable;
use msgpack::Decoder;

fn main() {
    let buf = [0x92, 0x2a, 0xaa, 0x74, 0x68, 0x65, 0x20, 0x41, 0x6e, 0x73, 0x77, 0x65, 0x72];

    let mut decoder = Decoder::new(&buf[..]);

    let res: (u8, String) = Decodable::decode(&mut decoder).unwrap();

    assert_eq!((42u8, "the Answer".to_string()), res);
}

RMP also allows to automatically serialize/deserialize custom structures using rustc_serialize reflection. To enable this feature, derive RustcEncodable and RustcDecodable attributes as shown in the following example:

extern crate rmp as msgpack;
extern crate rustc_serialize;

use rustc_serialize::{Encodable, Decodable};
use msgpack::{Encoder, Decoder};

#[derive(RustcEncodable, RustcDecodable, PartialEq, Debug)]
struct Custom {
    id: u32,
    key: String,
}

fn main() {
    let val = Custom { id: 42u32, key: "the Answer".to_string() };

    let mut buf = [0u8; 13];

    val.encode(&mut Encoder::new(&mut &mut buf[..]));

    assert_eq!([0x92, 0x2a, 0xaa, 0x74, 0x68, 0x65, 0x20, 0x41, 0x6e, 0x73, 0x77, 0x65, 0x72], buf);

    // Now try to unpack the buffer into the initial struct.
    let mut decoder = Decoder::new(&buf[..]);
    let res: Custom = Decodable::decode(&mut decoder).ok().unwrap();

    assert_eq!(val, res);
}

Versioning

This project adheres to Semantic Versioning. However until 1.0.0 comes there will be the following rules:

• Any API/ABI breaking changes will be notified in the changelog explicitly and results in minor version bumping.
• API extending features results in minor version bumping.
• Non-breaking bug fixes and performance improving results in patch version bumping.