centratelemedia / melody

:notes: Minimalist websocket framework for Go

melody

🎶 Minimalist websocket framework for Go.

Melody is websocket framework based on github.com/gorilla/websocket that abstracts away the tedious parts of handling websockets. It gets out of your way so you can write real-time apps. Features include:

• Clear and easy interface similar to net/http or Gin.
• A simple way to broadcast to all or selected connected sessions.
• Message buffers making concurrent writing safe.
• Automatic handling of sending ping/pong heartbeats that timeout broken sessions.
• Store data on sessions.

Install

go get github.com/olahol/melody

Example: chat

Using Gin:

package main

import (
	"github.com/gin-gonic/gin"
	"github.com/olahol/melody"
	"net/http"
)

func main() {
	r := gin.Default()
	m := melody.New()

	r.GET("/", func(c *gin.Context) {
		http.ServeFile(c.Writer, c.Request, "index.html")
	})

	r.GET("/ws", func(c *gin.Context) {
		m.HandleRequest(c.Writer, c.Request)
	})

	m.HandleMessage(func(s *melody.Session, msg []byte) {
		m.Broadcast(msg)
	})

	r.Run(":5000")
}

Using Echo:

package main

import (
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"github.com/olahol/melody"
	"net/http"
)

func main() {
	e := echo.New()
	m := melody.New()

	e.Use(middleware.Logger())
	e.Use(middleware.Recover())

	e.GET("/", func(c echo.Context) error {
		http.ServeFile(c.Response().Writer, c.Request(), "index.html")
		return nil
	})

	e.GET("/ws", func(c echo.Context) error {
		m.HandleRequest(c.Response().Writer, c.Request())
		return nil
	})

	m.HandleMessage(func(s *melody.Session, msg []byte) {
		m.Broadcast(msg)
	})

	e.Logger.Fatal(e.Start(":5000"))
}

Example: gophers

package main

import (
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"github.com/olahol/melody"
)

type GopherInfo struct {
	ID, X, Y string
}

func main() {
	r := gin.Default()
	m := melody.New()

	r.GET("/", func(c *gin.Context) {
		http.ServeFile(c.Writer, c.Request, "index.html")
	})

	r.GET("/ws", func(c *gin.Context) {
		m.HandleRequest(c.Writer, c.Request)
	})

	m.HandleConnect(func(s *melody.Session) {
		ss, _ := m.Sessions()

		for _, o := range ss {
			value, exists := o.Get("info")

			if !exists {
				continue
			}

			info := value.(*GopherInfo)

			s.Write([]byte("set " + info.ID + " " + info.X + " " + info.Y))
		}

		id := uuid.NewString()
		s.Set("info", &GopherInfo{id, "0", "0"})

		s.Write([]byte("iam " + id))
	})

	m.HandleDisconnect(func(s *melody.Session) {
		value, exists := s.Get("info")

		if !exists {
			return
		}

		info := value.(*GopherInfo)

		m.BroadcastOthers([]byte("dis "+info.ID), s)
	})

	m.HandleMessage(func(s *melody.Session, msg []byte) {
		p := strings.Split(string(msg), " ")
		value, exists := s.Get("info")

		if len(p) != 2 || !exists {
			return
		}

		info := value.(*GopherInfo)
		info.X = p[0]
		info.Y = p[1]

		m.BroadcastOthers([]byte("set "+info.ID+" "+info.X+" "+info.Y), s)
	})

	r.Run(":5000")
}

More examples

Documentation

Contributors

FAQ

If you are getting a 403 when trying to connect to your websocket you can change allow all origin hosts:

m := melody.New()
m.Upgrader.CheckOrigin = func(r *http.Request) bool { return true }