Transform streams for writing Chrome App native messaging hosts in Node.js.

npm i -S chrome-native-messaging

The module exports Input, Output, and Transform transform streams.

Input streams transform bytes to objects.

Output streams transform objects to bytes.

Use Transform to easily create custom object-to-object transform streams.

var nativeMessage = require('chrome-native-messaging');

process.stdin
    .pipe(new nativeMessage.Input())
    .pipe(new nativeMessage.Transform(function(msg, push, done) {
        var reply = getReplyFor(msg); // Implemented elsewhere by you.
        push(reply);                  // Push as many replies as you like.
        done();                       // Call when done pushing replies.
    }))
    .pipe(new nativeMessage.Output())
    .pipe(process.stdout)
;

The app directory contains a sample Chrome App.

The host directory contains a native messaging host that you can send messages to.

Go to the Chrome Extensions page (chrome://extensions/), hit "Load unpacked extension...", and select this project's app directory.

SUPER IMPORTANT: Find the ID your app received when you loaded it and copy it to the host manifest in the host directory.

SUPER IMPORTANT ON MACS: The path to the host must be absolute. Make sure the "path" property in the manifest is correct (it's probably not unless you're me).

Install the host manifest:

sudo host/register.sh

On Windows (Run as Administrator):

host\register.bat

Open a new tab and hit Apps in the upper left. Launch the example app and send yourself messages.

Run npm test for the unit tests.

json2msg.js is a script that can convert lines of JSON into native messages. Use it to send messages to your host to see how it responds.

Pipe the output of your host to msg2json.js to see what its output looks like.

./json2msg.js < test.json | ./host/my_host.js | ./msg2json.js

On Windows:

node json2msg.js < test.json | node host\my_host.js | node msg2json.js

Enabling logging in Chrome can help find problems finding the manifest.

Quit Chrome first.

open -a Google\ Chrome --args --enable-logging --v=1

On Windows:

start chrome --enable-logging --v=1

View the log like this:

less ~/Library/Application\ Support/Google/Chrome/chrome_debug.log

On Windows:

type "C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\chrome_debug.log"

More info: http://www.chromium.org/for-testers/enable-logging