library for golang, a realtime application framework.
Latest commit e9f0a9b Aug 11, 2016 @googollee committed on GitHub Merge pull request #139 from holygeek/master
Fix racy read/increment of for emits with ack

GoDoc Build Status is an implementation of in golang, which is a realtime application framework.

It is compatible with latest implementation of in node.js, and supports room and namespace.

  • for compatability with 0.9.x, please use branch 0.9.x *


Install the package with:

go get

Import it with:

import ""

and use socketio as the package name inside the code.


Please check the example folder for details.

package main

import (


func main() {
    server, err := socketio.NewServer(nil)
    if err != nil {
    server.On("connection", func(so socketio.Socket) {
        log.Println("on connection")
        so.On("chat message", func(msg string) {
            log.Println("emit:", so.Emit("chat message", msg))
            so.BroadcastTo("chat", "chat message", msg)
        so.On("disconnection", func() {
            log.Println("on disconnect")
    server.On("error", func(so socketio.Socket, err error) {
        log.Println("error:", err)

    http.Handle("/", server)
    http.Handle("/", http.FileServer(http.Dir("./asset")))
    log.Println("Serving at localhost:5000...")
    log.Fatal(http.ListenAndServe(":5000", nil))

Acknowledgements in 1.X.X

See documentation about acknowledgements

Sending ACK with data from SERVER to CLIENT
  • Client-side
 //using client-side
 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 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
//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)


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