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A space-efficient object serialization library for NodeJS
C++ JavaScript
Tag: v0.1

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node-msgpack is an addon for node.js that provides an API for serializing and de-serializing JavaScript objects using the MessagePack library. The performance of this addon compared to the native JSON object is quite good, and the space required for serialized data is far less than JSON.


node-msgpack outperforms the built-in JSON.stringify() and JSON.parse() methods handily. The following tests were performed with 500,000 instances of the JavaScript object {'abcdef' : 1, 'qqq' : 13, '19' : [1, 2, 3, 4]}:

  • JSON.stringify() 7.17 seconds
  • JSON.parse(JSON.stringify()) 22.18 seconds
  • msgpack.pack() 5.80 seconds
  • msgpack.unpack(msgpack.pack()) 8.62 seconds

Note that node-msgpack produces and consumes Buffer objects, and a such does not incur encoding/decoding overhead when performing I/O with native strings.


This module provides two methods: pack(), which consumes a JavaScript object and produces a node Buffer object; and unpack(), which consumes a node Buffer object and produces a JavaScript object.

The below code snippet packs and then unpacks a JavaScript object, verifying the resulting object at the end using assert.deepEqual().

var assert = require('assert');
var msgpack = require('msgpack');

var o = {"a" : 1, "b" : 2, "c" : [1, 2, 3]};
var b = msgpack.pack(o);
var oo = msgpack.unpack(b);

assert.deepEqual(oo, o);

As a convenience, a higher level streaming API is provided in the msgpack.Stream class, which can be constructed around a net.Stream instance. This object emits msg events when an object has been received.

var msgpack = require('msgpack');

// ... get a net.Stream instance, s, from somewhere
var ms = new msgpack.Stream(s);
ms.addListener('msg', function(m) {
    sys.debug('received message: ' + sys.inspect(m));

Command Line Utilities

As a convenience and for debugging, bin/json2msgpack and bin/msgpack2json are provided to convert JSON data to and from MessagePack data, reading from stdin and writing to stdout.

% echo '[1, 2, 3]' | ./bin/json2msgpack | xxd -
0000000: 9301 0203                                ....
% echo '[1, 2, 3]' | ./bin/json2msgpack | ./bin/msgpack2json 

Building and installation

This module depends on an unreleased feature of node.js; you must build it against a tree that contains change 3768aaae. An official release that contains this change should be out shortly.

Installation is a manual process: use make to build the add-on, then manually copy it to wherever your node.js installation will look for it (or add the build directory to your $NODE_PATH).

% ls
LICENSE  Makefile  deps/  src/  tags  test.js
% make

The MessagePack library on which this depends is packaged with node-msgpack and will be built as part of this process.

Note: MessagePack may fail to build if you do not have a modern version of gcc in your $PATH. On Mac OS X Snow Leopard (10.5.x), you may have to use gcc-4.2, which should come with your box but is not used by default.

% make CC=gcc-4.2 CXX=gcc-4.2
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