Socket.io

WebSocket wrapper for Fiber with events support and inspired by Socket.io

Note: Requires Go 1.20 and above

Install

go get -u github.com/gofiber/fiber/v2
go get -u github.com/gofiber/contrib/socketio

Signatures

// Initialize new socketio in the callback this will
// execute a callback that expects kws *Websocket Object
// and optional config websocket.Config
func New(callback func(kws *Websocket), config ...websocket.Config) 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) 

Example

package main

import (
    "encoding/json"
    "fmt"
    "log"

    "github.com/gofiber/contrib/socketio"
    "github.com/gofiber/contrib/websocket"
    "github.com/gofiber/fiber/v2"
)

// 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 message.to
    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.Printf("Connection event 1 - User: %s", ep.Kws.GetStringAttribute("user_id"))
    })

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

        // DO YOUR BUSINESS HERE

        // --->
    })

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

        fmt.Printf("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 {
            fmt.Println(err)
            return
        }

        // 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 {
            fmt.Println(err)
        }
    })

    // 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.Printf("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.Printf("Close event - User: %s", ep.Kws.GetStringAttribute("user_id"))
    })

    // On error event
    socketio.On(socketio.EventError, func(ep *socketio.EventPayload) {
        fmt.Printf("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)
    }))

    log.Fatal(app.Listen(":3000"))
}

---

Supported events

Const	Event	Description
EventMessage	message	Fired when a Text/Binary message is received
EventPing	ping	More details here
EventPong	pong	Refer to ping description
EventDisconnect	disconnect	Fired on disconnection. The error provided in disconnection event as defined in RFC 6455, section 11.7.
EventConnect	connect	Fired on first connection
EventClose	close	Fired when the connection is actively closed from the server. Different from client disconnection
EventError	error	Fired when some error appears useful also for debugging websockets

Event Payload object

Variable	Type	Description
Kws	*Websocket	The connection object
Name	string	The name of the event
SocketUUID	string	Unique connection UUID
SocketAttributes	map[string]string	Optional websocket attributes
Error	error	(optional) Fired from disconnection or error events
Data	[]byte	Data used on Message and on Error event, contains the payload for custom events

Socket instance functions

Name	Type	Description
SetAttribute	void	Set a specific attribute for the specific socket connection
GetUUID	string	Get socket connection UUID
SetUUID	error	Set socket connection UUID
GetAttribute	string	Get a specific attribute from the socket attributes
EmitToList	void	Emit the message to a specific socket uuids list
EmitTo	error	Emit to a specific socket connection
Broadcast	void	Broadcast to all the active connections except broadcasting the message to itself
Fire	void	Fire custom event
Emit	void	Emit/Write the message into the given connection
Close	void	Actively close the connection from the server

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

kws.Conn