wsx

WebSockets with extensions, implemented in JavaScript.

Introduction

WSX provides a lightweight abstraction layer over WebSockets, greatly increasing developer productivity while aiming to provide blazing fast transmission rates over the network without sacrificing stability and scalability.

Getting started

Please refer to the directory of examples to see more comprehensive walkthroughs leveraging the possibilities within the library.

Initializing communication channels

import Client from 'wsx/client';
import Server from 'wsx/server';
 
const wsxServer = new Server({ port: 3000 });
const wsxClient = new Client('ws://localhost:3000');

See the API Reference for further options.

Pro tip: WSX tries to detect its environment automatically. This means that import Server from 'wsx'; is a valid statement for Node environments, and import Client from 'wsx'; is a valid statement for browser environments.

Sending and receiving messages

WSX features an event-based messaging system with a syntax familiar for Socket.IO users. Messages are serialized and deserialized automatically.

Example

// Register an event handler on the server side for message type `echo`
wsxServer.on('message:echo', (client, payload) => {
  client.send('echo', payload);
});
 
// Register an event handler on the client side for message type `echo`
wsxClient.on('message:echo', (payload) => {
  console.log('Received message with type `echo` and the following payload:');
  console.log(payload);
});
 
// Transmit a message with type `echo` to the server
wsxClient.send('echo', 'Hello, World!');

Multiple recipients

You can broadcast messages or send them to client groups.

wsxServer.on('message', (client, data) => {
  // Forward the message to everyone else except for the client that sent it
  client.broadcast(data);
 
  // Forward the message to everyone, including the client that sent it
  wsxServer.clients.send(data);
 
  // Forward the message to a specific group of clients
  wsxServer.getClientGroup('clientGroupId').send(data);
});

Client groups

Client groups can be established on the server to handle multiple clients with ease. Their underlying Set of clients is managed automatically, meaning that you don't need to care about removing disconnected clients.

wsxServer.on('message:join', (client, groupId) => {
  // Inexistent client groups are created automatically
  wsxServer.getClientGroup(groupId).add(client);
  client.broadcast('join', groupId);
});
 
wsxServer.on('message:leave', (client, groupId) => {
  // Client groups with zero clients are destroyed automatically
  wsxServer.getClientGroup(groupId).remove(client);
  client.broadcast('leave', groupId);
});
 
wsxClient.send('join', 'developers');

Error handling

Message transmission errors are handled asynchronously:

wsxServer.on('error', (error, client) => {
  // Server error
  if (client) {
    // The error has a client involved
  }
});
 
wsxClient.on('error', () => {
  // Client error
});

API Reference

Client

Extends EventEmitter

WebSocket client with extensions.

base

Direct reference to the underlying WebSocket client implementation.

constructor

Parameters

• url string URL of the WebSocket server to which to connect.
• options [Object] Options to construct the client with.
  • options.protocols [Array<string>] Protocols to be used if possible.
  • options.plugins [Array<Function>] Plugins to be used, each defined as a function taking the constructed client instance as a parameter.

send

Transmits data to the server.

Parameters

• params [...Any] Data to be sent.

disconnect

Closes the connection or connection attempt, if any.

Parameters

• code [number] Status code explaining why the connection is being closed.
• reason [string] A human-readable string explaining why the connection is closing. This string must be no longer than 123 bytes of UTF-8 text (not characters).

connect

Connection event, fired when the client has connected successfully.

disconnect

Disconnection event, fired when the client disconnects.

Parameters

• code number Close status code sent by the server.
• reason string Reason why the server closed the connection.
• wasClean boolean Indicates whether or not the connection was cleanly closed.

message

Generic message event, fired when any message is received.

Parameters

• data Any Full message data.

message:[type]

Typeful message event, fired when a typeful message is received.

Parameters

• payload Any Payload of the message.

error

Error event, fired when an unexpected error occurs.

ClientGroup

Extends Set

Represents a group of clients.

clear

Removes all clients from the group.

delete

Removes the specified client from the group.

Parameters

• client Object Client to be removed.

Returns boolean true if the client has been removed successfully; otherwise false.

send

Transmits data to every client in the group.

Parameters

• params [...Any] Data to be sent.

Server

Extends EventEmitter

WebSocket server with extensions.

base

Direct reference to the underlying WebSocket server implementation.

clients

Store for every connected client.

constructor

Parameters

• options Object Options to construct the server with. Every option is passed to the underlying WebSocket server implementation.
  • options.plugins [Array<Function>] Plugins to be used, each defined as a function taking the constructed server instance as a parameter.
• successCallback Function Function to be executed on successful initialization.

getClientGroup

Retrieves a client group by its ID. Creates a new group if necessary.

Parameters

• id string ID of the group.

Returns Group

connect

Connection event, fired when a client has connected successfully.

Parameters

• client Object Connected client instance.

disconnect

Disconnection event, fired when a client disconnects.

Parameters

• client Object Disconnected client instance.
• code number Close status code sent by the client.
• reason string Reason why the client closed the connection.

error

Error event, fired when an unexpected error occurs.

Parameters

• error Object Error object.
• client [Object] Client causing the error.

message:[type]

Typeful message event, fired when a typeful message is received.

Parameters

• client Object Sender of the message.
• payload Any Payload of the message.

message

Generic message event, fired when any message is received.

Parameters

• client Object Sender of the message.
• data Any Full message data.

ClientExtensions

Provides method extensions for WebSocket clients.

Parameters

• client
• superSend
• params ...Any

send

Transmits data to the client.

Parameters

• client Object Client instance of the receiver.
• superSend Function Super send function of the client.
• params [...Any] Data to be sent.

broadcast

Transmits data to everyone else except for the client that starts it.

Parameters

• clients Array<Object> Client instances to broadcast data between.
• senderClient Object Client instance of the sender.
• params [...Any] Data to be sent.

MessageSerializer

Serializes and deserializes messages transmitted over a WebSocket connection.

Parameters

• data

serializeMessage

Serializes a message to be sent over a WebSocket connection.

Parameters

• data Any Full message data.

Returns (string | Buffer | ArrayBuffer)

deserializeMessage

Deserializes a message received over a WebSocket connection.

Parameters

• data Any Full message data.

Returns Any