Go WebSocket

An easy way to get started with websockets in golang.

This module tracks user sessions, can recover temporarily lost connections, and compresses data through gzip if supported by the client.

Installation

Go (server)

go get github.com/AspieSoft/go-websocket

JavaScript (client)

<script src="https://cdn.jsdelivr.net/gh/AspieSoft/go-websocket@1.4.8/client.min.js" defer></script>

Usage

Go (server)

import (
  "net/http"

  "github.com/AspieSoft/go-websocket"
)

func main(){
  // setup a new websocket server
  server := websocket.NewServer("https://www.example.com")
  http.Handle("/ws", server.Handler())

  // optional: set a timeout for when disconnected clients can no longer reconnect with the same data
  server := websocket.NewServer("https://www.example.com", 30 * time.Second)

  // by default, data is compressed with gzip before being send between the server and client
  // this behavior can opptonally be disabled
  server.Gzip = false

  // by default, the server only reads requests up to 1 megabyte
  // this value can opptionally be changed
  server.ReqSize = 1024 // KB


  static := http.FileServer(http.Dir("./public/"))
  http.Handle("/", static)

  server.Connect(func(client *websocket.Client){
    // client connected

    // localstorage that stays with the client, and verifies their session
    // map[string]interface{}
    client.Store["key"] = "value"

    server.Broadcast("notify", "a new user connected to the server")
    server.Broadcast("user", client.ClientID)

    client.On("message", func(msg interface{}) {
      // client sent a message

      // optional: enforce a specific message type
      str := websocket.ToType[string](msg)
      b := websocket.ToType[[]byte](msg)
      i := websocket.ToType[int](msg)
      bool := websocket.ToType[bool](msg)
      json := websocket.ToType[map[string]interface{}](msg)
      array := websocket.ToType[[]interface{}](msg)
    })

    // send data to client
    client.Send("message", "my message to the client")

    client.Send("json", map[string]interface{}{
      "jsondata": "my json data",
      "key": "value",
      "a": 1,
    })

    client.on("send-to-friend", func(msg interface{}){
      json := websocket.ToType[map[string]interface{}](msg)

      // send a message to a different client
      server.send(json["friendsClientID"], json["msg"])

      // do other stuff...
      client.send("send-from-friend", map[string]interface{
        "ClientID": client.ClientID,
        "msg": "General Kenobi!",
      })
    })

    client.Disconnect(func(code int) {
      // when client disconnects
      server.Broadcast("disconnected", client.ClientID)
    })
  })

  server.On("kick", func(client *websocket.Client, msg interface{}) {
    friendsClientID := websocket.ToType[string](msg)

    // force a client to leave the server
    server.Kick(friendsClientID, 1000)

    server.Broadcast("kicked", friendsClientID+" was kicked by "+client.ClientID)
  })

  server.On("kick-all", func(client *Client, msg interface{}) {
    // kick every client from the server
    server.KickAll()
  })

  log.Fatal(http.ListenAndServe(":3000", nil))
}

JavaScript (client)

const socket = new ServerIO(); // will default to current origin
// or
const socket = new ServerIO('https://www.example.com'); // optional: specify a different origin

socket.connect(function(initial){
  // connected to server

  socket.send('message', "my message to the server");

  if(initial){
    // very first time connecting to the server
  }else{
    // reconnecting after a previous disconnect
  }
});

socket.on('message', function(msg){
  console.log('I got a new message:', msg);

  socket.send('json', {
    jsondata: 'my json data',
    key: 'value',
    a: 1,
  });
});

socket.on('json', function(msg){
  console.log('pre-parsed json:', msg.jsondata);
});

socket.on('notify', function(msg){
  console.log(msg);
});

let myNewFriend = null;
socket.on('user', function(msg){
  myNewFriend = msg;

  socket.send('send-to-friend', {
    friendsClientID: myNewFriend,
    msg: 'Hello, There!',
  })
});

socket.on('send-from-friend', function(msg){
  socket.send('kick', myNewFriend);
});

socket.on('kicked', function(msg){
  socket.send('kick-all');

  // run disconnect
  socket.disconnect();

  // run reconnect
  socket.connect();
});

socket.disconnect(function(status){
  // on disconnect
  if(status === 1000){
    console.log('disconnected successfully');
  }else if(status === 1006){
    console.warn('error: disconnected by accident, auto reconnecting...');
  }else{
    console.error('error:', status);
  }
});


socket.on('notifications', function(){
  console.log('my notification');
})

// stop listining to a message, and remove all client listeners of that type
socket.off('notifications');

// stop the server from sending messages, but keep the listener on the client
socket.off('notifications', false);

// request the server to send messages again
socket.on('notifications');


socket.error(function(type){
  // handle errors
  // Note: disconnection errors will Not trigger this method

  if(type === 'migrate'){
    // the client reconnected to the server, but the server failed to migrate the clients old data to the new connection
    // client listeners should still automatically be restored
  }
});