Mesa

Mesa is a WebSocket library that provides extra features such as heartbeats, automatic reconnection handling and Pub/Sub support.

ws, which Mesa wraps, on its own usually isn't enough. It doesn't provide features out of the box required by modern applications which means many users either stick to Socket.IO or write their own implementations around the ws package. Mesa was extracted from the WebSocket implementation in @cryb/api after we wanted to add robust WebSocket capabilities to other services.

In a nutshell, Mesa provides a simple, configurable wrapper that provides support for pub/sub, authentication, heartbeats and more and has powered production applications with millions of users since mid-2019.

Features

• Heartbeat support
• Reconnection support
• Authentication support
• Message redelivery support
• Replication support via Redis
• and many more...

Installation

This library is available on the NPM registry. To install, run:

npm install @cryb/mesa --save

If you're using Yarn, run:

yarn add @cryb/mesa

Usage

Server Side

Import the library as you would with any other Node package:

const Mesa = require('@cryb/mesa').default
// or using ES modules
import Mesa from '@cryb/mesa'

To create a Mesa server, simply write:

const mesa = new Mesa({ port: 4000 })

We provide expansive configuration support for customising Mesa to your needs. See Server Configuration for options.

Mesa uses EventEmitter in order to inform the application of events. Here's an example of a simple Mesa application:

mesa.on('connection', client => {
  console.log('Client connected')

  client.on('message', message => {
    const { data, type } = message

    console.log('Received', data, type)
  })

  client.on('disconnect', (code, reason) => {
    console.log('Client disconnected')
  })
})

Sending messages to clients or globally is easy. Simply import Message from Mesa and use the following API:

// Sending globally
mesa.send(new Message(0, { disabled: true }, 'MANIFEST_UPDATE'))

// You can also limit to certain authenticated client ids
mesa.send(new Message(0, { content: 'Hey!' }, 'NEW_MESSAGE'), ['0', '1', '2']) // Only send to connected clients with id 0, 1, 2
mesa.send(new Message(0, { userId: '1', status: 'online' }, 'STATUS_UPDATE'), ['*'], ['1']) // Send to all connected clients except client with id 1

// Sending to clients
client.send(new Message(0, {}, 'LOGOUT'))

It's your call on how you wish to handle messages, but we recommend using a switch statement based on the type:

client.on('message', message => {
  const { data, type } = message

  switch(type) {
    case 'STATUS_UPDATE':
    handleStatusUpdate(data.status, client.id)
    break
    case 'TYPING_STATUS':
    setUserTyping(data.typing, client.id)
    break
  }
})

Server Guides

We supply a number of guides for fully utilising Mesa server:

Replication

• Using Pub/Sub
  • Replicate messages across multiple Mesa instances
• Using Namespaces
  • Run multiple Mesa instances in different namespaces

Clients

• Authenticating Clients
  • Authenticate connecting clients

Messages

• Redelivering Messages
  • Ensure clients receive missed messages upon reconnection
• Handling Messages using Portal
  • Receive and handle client messages from anywhere in your codebase
• Sending Messages using Dispatcher
  • Send messages to clients from anywhere in your codebase

Middleware

• Using Middleware
  • Extend your Mesa server with new functionality and minimal effort
• Creating Middleware
  • Create powerful middleware handlers to hook into Mesa's event system

Client Side

Note: we currently provide client libraries for Node-based JavaScript. For a browser-based client library, see mesa-js-client.

Import the Client export from the library as you would with any other Node package:

const { Client } = require('@cryb/mesa')
// or using ES modules
import { Client } from '@cryb/mesa'

To connect to a Mesa server, simply write:

const client = new Client('ws://localhost:4000')

Note: the URL provided needs to be the standard WebSocket connection URI for your Mesa server.

We provide expansive configuration support for customising the Mesa client to your needs. See Client Configuration for options.

We use the EventEmitter in order to inform the application of events from the Mesa server. Here's an example of a simple client application:

const client = new Client('ws://localhost:4000')

client.on('connection', () => {
  console.log('Client connected')
})

client.on('message', message => {
  const { data, type } = message

  console.log('Received', data, type)
})

client.on('disconnected', (code, reason) => {
  console.log('Client disconnected')
})

Sending messages to the server works the same way as sending messages to clients from Mesa:

client.send(new Message(0, { status: 'online' }, 'STATUS_UPDATE'))

Handling messages is identical to how messages are handled on the server, so again it's your choice on how you choose to implement this

Client Guides

We supply a number of guides for fully utilising Mesa client:

• Authentication
  • Authenticate clients against your Mesa server

Extras

• Chat App
  • chat.mesa.ws is an example chat app using Mesa.Server and mesa-js-client. Source Code
• Echo Server
  • echo.mesa.ws is an echo server for testing Mesa connections
• Gateway Server
  • Mega is a gateway server utilising Mesa that can be configured via environment variables
• Client Libraries
  • Our guidance on using available client libraries or creating your own

License

MIT

Questions / Issues

If you have an issues with @cryb/mesa, please either open a GitHub issue, contact a maintainer or join the Cryb Discord Server and ask in #tech-support.