go-socket.io

go-socket.io is an implementation of Socket.IO in Golang, which is a realtime application framework.

Currently this library supports 1.4 version of the Socket.IO client. It supports room and namespaces.

Go 1.9+ is required!

Help wanted This project is looking for contributors to help fix bugs and implement new features. Please check Issue 192. All help is much appreciated.

• for compatibility with Socket.IO 0.9.x, please use branch 0.9.x *

Contents

• Install
• Last changes
• Example
• Contributors
• License

Install

Install the package with:

go get github.com/googollee/go-socket.io

Import it with:

import "github.com/googollee/go-socket.io"

and use socketio as the package name inside the code.

Last changes

Important changes:

Short info	Description	Date
Changed signature of OnError	Changed signature of OnError From: server.OnError(string, func(error)) To: server.OnError(string, func(Conn, error))	2019-10-16

Example

Please check the example folder for details.

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/googollee/go-socket.io"
)

func main() {
	server, err := socketio.NewServer(nil)
	if err != nil {
		log.Fatal(err)
	}
	server.OnConnect("/", func(s socketio.Conn) error {
		s.SetContext("")
		fmt.Println("connected:", s.ID())
		return nil
	})
	server.OnEvent("/", "notice", func(s socketio.Conn, msg string) {
		fmt.Println("notice:", msg)
		s.Emit("reply", "have "+msg)
	})
	server.OnEvent("/chat", "msg", func(s socketio.Conn, msg string) string {
		s.SetContext(msg)
		return "recv " + msg
	})
	server.OnEvent("/", "bye", func(s socketio.Conn) string {
		last := s.Context().(string)
		s.Emit("bye", last)
		s.Close()
		return last
	})
	server.OnError("/", func(s socketio.Conn, e error) {
		fmt.Println("meet error:", e)
	})
	server.OnDisconnect("/", func(s socketio.Conn, reason string) {
		fmt.Println("closed", reason)
	})
	go server.Serve()
	defer server.Close()

	http.Handle("/socket.io/", server)
	http.Handle("/", http.FileServer(http.Dir("./asset")))
	log.Println("Serving at localhost:8000...")
	log.Fatal(http.ListenAndServe(":8000", nil))
}

Acknowledgements in go-socket.io 1.X.X

See documentation about acknowledgements

Sending ACK with data from SERVER to CLIENT

• Client-side

 //using client-side socket.io-1.X.X.js
 socket.emit('some:event', JSON.stringify(someData), function(data){
       console.log('ACK from server wtih data: ', data));
 });

• Server-side

// The return type may vary depending on whether you will return
// In golang implementation of Socket.IO don't used callbacks for acknowledgement,
// but used return value, which wrapped into ack package and returned to the client's callback in JavaScript
so.On("some:event", func(msg string) string {
	return msg //Sending ack with data in msg back to client, using "return statement"
})

Sending ACK with data from CLIENT to SERVER

• Client-side

//using client-side socket.io-1.X.X.js
//last parameter of "on" handler is callback for sending ack to server with data or without data
socket.on('some:event', function (msg, sendAckCb) {
    //Sending ACK with data to server after receiving some:event from server
    sendAckCb(JSON.stringify(data)); // for example used serializing to JSON
}

• Server-side

//You can use Emit or BroadcastTo with last parameter as callback for handling ack from client
//Sending packet to room "room_name" and event "some:event"
so.BroadcastTo("room_name", "some:event", dataForClient, func (so socketio.Socket, data string) {
	log.Println("Client ACK with data: ", data)
})

// Or

so.Emit("some:event", dataForClient, func (so socketio.Socket, data string) {
	log.Println("Client ACK with data: ", data)
})

Broadcast to All connected Client

• Server-side

//Add all connected user to a room, in example? "bcast"
server.OnConnect("/", func(s socketio.Conn) error {
	s.SetContext("")
	fmt.Println("connected:", s.ID())
	s.Join("bcast")
	return nil
})

//Broadcast message to all connected user
server.BroadcastToRoom("", "bcast", "event:name", msg)

• Client-side

socket.on('some:event', function (msg) {
	console.log(msg);
});

Catch Disconnected reason

• Server-side

so.OnDisconnect("/", func(so socketio.Conn, reason string) {
  	log.Println("closed", reason)
})

Possible reasons:

Reason	Side	Description
client namespace disconnect	Client Side	Got disconnect packet from client

Community

Telegram chat: @go_socketio

Contributors

This project exists thanks to all the people who contribute. [Contribute].

License

The 3-clause BSD License - see LICENSE for more details