msgpack-ts

msgpack-ts

Fast MessagePack implementation in TypeScript. Designed as a faster, smaller alternative to msgpack-lite. Both the Encoder and Decoder are quite configurable, but performance was prioritized with as little branching as possible.

TODO

• Add Closure-compiled browser distribution
• Add thorough tests
• Add benchmarks

You can optimize further

If your MessagePack traffic contains many or large binary buffers, you may want to fork this repo and alter the takeBinary(length) method of the Decoder to use this.buffer.subarray in place of this.buffer.slice, because Uint8Array.slice() creates a copy of the bytes. This library assumes that your messages will not consist primarily of binary objects and thus it is undesirable to return subviews of the same buffer being decoded because they will hold references to the entire buffer that was decoded, likely keeping it in memory when it is not needed.

Quick Start

For more information, read the docs.

Install the library via NPM: npm i --save-dev msgpack-ts.

import { encode, decode, Decoder } from "msgpack-ts";

/**
 * Both x and y will be in range [0, 255].
 */
class Coordinate
{
    static encode(coord: Coordinate): Uint8Array
    {
        return new Uint8Array([coord.x, coord.y]);
    }

    static decode(data: Uint8Array): Coordinate
    {
        return new Coordinate(data[0], data[1]);
    }

    static backwardsDecode(data: Uint8Array): Coordinate
    {
        return new Coordinate(data[1], data[0]);
    }

    constructor(
        readonly x: number,
        readonly y: number
    ) {}
}

function main()
{
    const message: SomeInterface = {
        type: "add-user",
        data: {
            firstName: "Jane",
            lastName: "Doe",
            age: 27,
            female: true,
            location: new Coordinate(10, 192),
            username: "janedoe92",
            passwordHash: new Uint8Array(32)
        }
    };

    encode.encoder.registerExt(Coordinate, 0, Coordinate.encode);
    decode.decoder.registerExt(0, Coordinate.decode);

    // encode() uses the encode.encoder instance
    const encoded = encode(message);

    // decode() uses the decode.decoder instance
    const decoded = decode<SomeInterface>(encoded);

    // Create separate instances if you need multiple configurations
    const myDecoder = new Decoder();
    myDecoder.nilValue = undefined;
    myDecoder.allowInvalidUTF8 = true;
    myDecoder.allowUnknownExts = true;
    myDecoder.registerExt(0, Coordinate.backwardsDecode);

    // Both Encoder and Decoder support cloning instances
    const slightlyDifferent = myDecoder.clone();
    slighlyDifferent.nilValue = null;
}

Documentation

class Encoder

static

• Encoder.global: Encoder

  A global Encoder instance, purely for convenience.

• Encoder.encode(data: any, initBuffSize?: number): Uint8Array

  Convenience function to call Encoder.global.encode().

constructor

• new Encoder(reserve = 128)

  Create a new Encoder instance. You may pass the number of bytes to allocate immediately as an encoding buffer, or it will default to 128.

instance

• Encoder.encode(data: any, reserve?: number): Uint8Array

  Encode a JavaScript object or primitive to MessagePack format. You may provide a second argument to ensure that a certain number of bytes is allocated for the encoding buffer before encoding begins.

• Encoder.registerExt<T>(ctor: new (...args: any[]) => T, type: number, encoderFn: (data: T) => Uint8Array)

  Register an encoder for an object class. type MUST be in the range [-128, 127] or a RangeError will be thrown. Negative types are reserved by the MessagePack spec and SHOULD not be used, unless this library does not provide an extension added to the spec or the implementation is found to be inadequate.

  Standard Extensions Registered By Default

  • -1 (Timestamp)

    JavaScript Date objects will be encoded using the standard Timestamp extension type, unless overriden.

• Encoder.resize(newSize: number)

  Release the current encoding buffer and allocate a new one of newSize bytes.

• Encoder.clone(): Encoder

  Creates an independent clone of the Encoder with the same configuration values and registered extensions.

class Decoder

static

• Decoder.global: Decoder

  A global Decoder instance, purely for convenience.

• Decoder.decode<T = any>(data: ArrayBuffer | Uint8Array): T

  Convenience function to call Decoder.global.decode().

constructor

• new Decoder()

  Creates a new Decoder instance.

instance

• Decoder.nilValue: null | undefined = null

  Value the MessagePack nil constant should be interpreted as.

• Decoder.allowInvalidUTF8 = false

  If false, an error will be thrown if a MessagePack str type is encountered and the data is not valid UTF-8. If true, the str data will be passed through opaquely as a Uint8Array.

• Decoder.allowUnknownExts = false

  If false, a RangeError will be thrown whenever an unrecognized extension type is encountered. If true, the extension data will be passed through opaquely as a Decoder.UnknownExt.

• Decoder.mapBehavior = Decoder.MapBehavior.PreferJSON

  Determines how MessagePack map values are decoded. See Decoder.MapBehavior for options.

• Decoder.decode<T = any>(data: ArrayBuffer | Uint8Array): T

  Decode MessagePack data into a JS object or primitive.

• Decoder.clone(): Decoder

  Creates an independent clone of the Decoder with the same configuration values and registered extensions.

interface Decoder.UnknownExtSeq

Opaque tuple of an extension type identifier and the raw data associated with it.

• type: number

  The extension type which did not have a registered decoder.

• data: Uint8Array

  The opaque data.

enum Decoder.MapBehavior

Determines Decoder behavior when a MessagePack map is encountered.

• PreferJSON = 0

  Maps will be decoded as native JS objects, unless a key is decoded whose JS type evaluates to object, in which case all decoded keys will be abandoned and the map will be decoded from scratch into an ES6 Map which supports arbitrary key types.

• AlwaysJSON = 1

  Maps will be always be decoded as native JS objects. This means all decoded keys will be coerced to strings, which is almost certainly undesirable if decoding maps with objects or arrays as keys.

• AlwaysES6Map = 2

  Maps will always be decoded as ES6 Map objects.