@pgostovic/message

Easy to use WebSocket-based messaging client and server. This module is optimized and intended for use in web browser/server communication.

Requests and Responses

With WebSockets there's no need to stick to the request/response idiom because communication is full-duplex. This is what makes WebSockets good at "pushing" from server to client. WebSockets are actually often only associated with server-initiated push; two-way client/server communication remains an underappreciated ability of WebSockets. This is probably because request/response is a very common (and useful!) way of doing client/server communication, but the WebSockets API doesn't explicitly support it. This module provides an easy way to do request/response (and more) with WebSockets.

Full-Duplex Performance Advantage

(http2?)

Fetch and XMLHttpRequest are easy to use but unfortunately they tie up sockets. Web browsers restrict the number of connections to unique hosts that can be held open at a time. This

With HTTP (i.e. XMLHttpRequest, fetch)

• request -> response
• request -> response 1, response 2,...response N
• request -> response, increment,...increment N

Usage

Here's a simple example to illustrate some basic communication.

Server

import http from 'http';
import { MessageServer } from '@pgostovic/message';

// Native Node.js HTTP server
const httpServer = http.createServer(() => {});
httpServer.listen(8080);

const messageServer = new MessageServer(httpServer);

messageServer.onMessage = async message => {
  const { type, data } = message;

  if (type === 'greet-me') {
    return `Hello ${data.name}`;
  }

  throw new Error(`Unsupported message type: ${type}`);
};

Client

import { MessageClient } from '@pgostovic/message';

const messageClient = new MessageClient('ws://localhost:8080');

const greeting = await messageClient.send('greet-me', { name: 'Patrick' });

console.log(greeting); // "Hello Patrick"

Note: this code won't work as-is because await can only be used in an async context.