Open-Channel

A self-hosting inter-process communication channel for NodeJS.

Design Purpose

Even if NodeJS provides its IPC communication abilities internally and there are a lot third party packages that provides IPC functionality. However, all of them require starting an IPC server or based on cluster/child_process, which are very unsuitable and may not work with the some situations:

1. The developer doesn't have authority to write any logic in the master process, e.g. your app runs under PM2 supervision.
2. If the IPC server is down, all communications will be lost and must manually restart the server.
3. The developer must set exact protocol and net port (probably) to communicate, which may not be available when run-time environment is changed.

Open-Channel is meant to resolve these problems. With it, you will have these advantages:

1. No need of master process accessibility, all code is written for a single process (whether it will be run as child-process or individual process).
2. No need to start the IPC server manually, the channel will ship it internally.
3. Automatically switch the best protocol to transmit, on Unit, it uses domain socket, on Windows, it uses named pipe by default and changed to net port when in cluster mode.
4. Automatically reconnect and resend messages if the connection is lost, always keep communications ongoing.
5. Sending messages even before the connection established, they will be queued and sent once connection is ready.

Example

const openChannel = require("open-channel").default;

var channel = openChannel(socket => {
    // This is a connection lister that passed to net.createServer().
    // The server instance will not be created until the first time calling 
    // channel.connect().
    // Put Your logic here to handle client connections and communications with 
    // the server.
});

// Gets a net.Socket instance connected to the server.
// you can pass an optional timeout argument in milliseconds to connect().
// The connection will not be immediately ready, but you still can send messages.
var socket = channel.connect();

// Put you logic here to communicate with the server.

API

• openChannel(connectionListener: (socket: net.Socket) => void): ProcessChannel

• openChannel(name: string, connectionListener: (socket: net.Socket) => void): ProcessChannel

  • name The name of the channel. It's required to set a unique name of the channel when you have multiple channels on the same machine.
  • connectionListener is set for net.createServer().

• channel.connect(timeout?: number): net.Socket Gets the socket client that will connect to the internal server.

  • timeout Default value is 5000ms.

• channel.name: string The same name passed to openChannel().

• channel.state: string Returns the status of the channel, which will either be initiated, connecting, connected or closed.

• channel.connected: boolean Whether the channel is connected to the internal server.

• socket.write() The client side write method has been re-written to implement sending messages even when the channel state is connecting.

• socket.destroy() The client side destroy method has been re-written to implement closing both the channel and the socket. (The internal server will still be working, and currently unable to close the channel on server side.)