Skip to main content
Version: fibernewrelic_v1.x.x


id: socketio

Release Test Security Linter

WebSocket wrapper for Fiber with events support and inspired by

Note: Requires Go 1.20 and above


go get -u
go get -u


// Initialize new socketio in the callback this will
// execute a callback that expects kws *Websocket Object
func New(callback func(kws *Websocket)) func(*fiber.Ctx) error
// Add listener callback for an event into the listeners list
func On(event string, callback func(payload *EventPayload))
// Emit the message to a specific socket uuids list
// Ignores all errors
func EmitToList(uuids []string, message []byte)
// Emit to a specific socket connection
func EmitTo(uuid string, message []byte) error
// Broadcast to all the active connections
// except avoid broadcasting the message to itself
func Broadcast(message []byte)
// Fire custom event on all connections
func Fire(event string, data []byte)


package main

import (


// MessageObject Basic chat message object
type MessageObject struct {
Data string `json:"data"`
From string `json:"from"`
Event string `json:"event"`
To string `json:"to"`

func main() {

// The key for the map is
clients := make(map[string]string)

// Start a new Fiber application
app := fiber.New()

// Setup the middleware to retrieve the data sent in first GET request
app.Use(func(c *fiber.Ctx) error {
// IsWebSocketUpgrade returns true if the client
// requested upgrade to the WebSocket protocol.
if websocket.IsWebSocketUpgrade(c) {
c.Locals("allowed", true)
return c.Next()
return fiber.ErrUpgradeRequired

// Multiple event handling supported
socketio.On(socketio.EventConnect, func(ep *socketio.EventPayload) {
fmt.Println(fmt.Sprintf("Connection event 1 - User: %s", ep.Kws.GetStringAttribute("user_id")))

// Custom event handling supported
socketio.On("CUSTOM_EVENT", func(ep *socketio.EventPayload) {
fmt.Println(fmt.Sprintf("Custom event - User: %s", ep.Kws.GetStringAttribute("user_id")))
// --->


// --->

// On message event
socketio.On(socketio.EventMessage, func(ep *socketio.EventPayload) {

fmt.Println(fmt.Sprintf("Message event - User: %s - Message: %s", ep.Kws.GetStringAttribute("user_id"), string(ep.Data)))

message := MessageObject{}

// Unmarshal the json message
// {
// "from": "<user-id>",
// "to": "<recipient-user-id>",
// "event": "CUSTOM_EVENT",
// "data": "hello"
err := json.Unmarshal(ep.Data, &message)
if err != nil {

// Fire custom event based on some
// business logic
if message.Event != "" {
ep.Kws.Fire(message.Event, []byte(message.Data))

// Emit the message directly to specified user
err = ep.Kws.EmitTo(clients[message.To], ep.Data, socketio.TextMessage)
if err != nil {

// On disconnect event
socketio.On(socketio.EventDisconnect, func(ep *socketio.EventPayload) {
// Remove the user from the local clients
delete(clients, ep.Kws.GetStringAttribute("user_id"))
fmt.Println(fmt.Sprintf("Disconnection event - User: %s", ep.Kws.GetStringAttribute("user_id")))

// On close event
// This event is called when the server disconnects the user actively with .Close() method
socketio.On(socketio.EventClose, func(ep *socketio.EventPayload) {
// Remove the user from the local clients
delete(clients, ep.Kws.GetStringAttribute("user_id"))
fmt.Println(fmt.Sprintf("Close event - User: %s", ep.Kws.GetStringAttribute("user_id")))

// On error event
socketio.On(socketio.EventError, func(ep *socketio.EventPayload) {
fmt.Println(fmt.Sprintf("Error event - User: %s", ep.Kws.GetStringAttribute("user_id")))

app.Get("/ws/:id", socketio.New(func(kws *socketio.Websocket) {

// Retrieve the user id from endpoint
userId := kws.Params("id")

// Add the connection to the list of the connected clients
// The UUID is generated randomly and is the key that allow
// socketio to manage Emit/EmitTo/Broadcast
clients[userId] = kws.UUID

// Every websocket connection has an optional session key => value storage
kws.SetAttribute("user_id", userId)

//Broadcast to all the connected users the newcomer
kws.Broadcast([]byte(fmt.Sprintf("New user connected: %s and UUID: %s", userId, kws.UUID)), true, socketio.TextMessage)
//Write welcome message
kws.Emit([]byte(fmt.Sprintf("Hello user: %s with UUID: %s", userId, kws.UUID)), socketio.TextMessage)


Supported events

EventMessagemessageFired when a Text/Binary message is received
EventPingpingMore details here
EventPongpongRefer to ping description
EventDisconnectdisconnectFired on disconnection. The error provided in disconnection event as defined in RFC 6455, section 11.7.
EventConnectconnectFired on first connection
EventClosecloseFired when the connection is actively closed from the server. Different from client disconnection
EventErrorerrorFired when some error appears useful also for debugging websockets

Event Payload object

Kws*WebsocketThe connection object
NamestringThe name of the event
SocketUUIDstringUnique connection UUID
SocketAttributesmap[string]stringOptional websocket attributes
Errorerror(optional) Fired from disconnection or error events
Data[]byteData used on Message and on Error event, contains the payload for custom events

Socket instance functions

SetAttributevoidSet a specific attribute for the specific socket connection
GetUUIDstringGet socket connection UUID
SetUUIDerrorSet socket connection UUID
GetAttributestringGet a specific attribute from the socket attributes
EmitToListvoidEmit the message to a specific socket uuids list
EmitToerrorEmit to a specific socket connection
BroadcastvoidBroadcast to all the active connections except broadcasting the message to itself
FirevoidFire custom event
EmitvoidEmit/Write the message into the given connection
ClosevoidActively close the connection from the server

Note: the FastHTTP connection can be accessed directly from the instance