Express Msgpack

Express and MessagePack, together at last. Uses @msgpack/msgpack by default.

Functionality

Provides transparent middleware that can be used to support clients requesting Accept: application/msgpack from endpoints using res.json or sending Content-Type: application/msgpack to any endpoint. You can continue to use req.body and res.json and expressMsgpack will handle the conversion in the background using @msgpack/msgpack (or any compatible library of your choice).

Installation

$ npm install --save express-msgpack
// or
$ yarn add express-msgpack

If you intend to use an alternative to @msgpack/msgpack (see Configuration) you can add the --no-optional flag; it's an optional dependency.

Usage

import msgpack from "express-msgpack";

// ...
app.use(msgpack());

CommonJS

const msgpack = require("express-msgpack").default;

// ...
app.use(msgpack());

Configuration

To configure, pass options when you configure the middleware. Currently supported options are:

Parameter	Description	Default
decoder	a function converting from MessagePack to JavaScript	@msgpack/msgpack#decode
encoder	a function converting from JavaScript to MessagePack	@msgpack/msgpack#encode (with a wrapper to convert the result to a Buffer)
mimeType	the MIME type to detect and set for MessagePack payloads	"application/msgpack"
limit	The byte limit of the body. This is the number of bytes or any string format supported by bytes	"100kb"

For example, to switch to the node-gyp C++ based msgpack library:

import msgpack from "express-msgpack";
import { pack, unpack } from "msgpack";

// ...
app.use(msgpack({ decoder: unpack, encoder: pack }));

Development

The project has code linting and testing, using the following commands:

• npm run e2e: run the smoke/E2E tests
• npm run lint: run the ESLint checks
• npm run ship: lint and run unit, integration and E2E tests
• npm test: run the Jest unit and integration tests
• npm test:watch: run the tests in watch mode

The tests are in the __tests__/ directory and are run using Jest. They're split into two files:

• unit.test.ts - mockist unit tests, to check specific internal details
• integration.test.ts - integration tests using SuperTest with a simple Express app using the middleware

There is also a smoke/ directory containing E2E/smoke tests for a deployed version of the package, used by bin/smoke.sh. If the --local argument is supplied to the script the local version is packaged and tested , otherwise the specified $TAG version is installed from the registry and tested.