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 ping/pong and session timeouts.
• Store data on sessions.

Install

go get gopkg.in/olahol/melody.v1

Example: sub/pub

package main

import (
	"log"
	"melody"

	"github.com/gin-gonic/gin"
)

func main() {
	m := melody.New()
	router := gin.Default()
	router.GET("/chat", func(context *gin.Context) {
		if err := m.HandleRequest(context.Writer, context.Request); err != nil {
			log.Println(err)
		}
	})

	m.HandleConnect(func(session *melody.Session) {
		ch := session.Request.URL.Query().Get("channel")
		if err := session.Subscribe(ch); err != nil {
			log.Println(err)
		}
	})

	m.HandleMessage(func(session *melody.Session, msg []byte) {
		if err := session.Publish(msg); err != nil {
			log.Println(err)
		}
	})

	m.HandleSentMessage(func(session *melody.Session, bytes []byte) {
		log.Printf("%+v", session.Channel().Online())
		log.Printf("%+v", string(bytes))
	})
	router.Run(":8080")
}

Example: chat

Using Gin:

package main

import (
	"github.com/gin-gonic/gin"
	"gopkg.in/olahol/melody.v1"
	"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"
	"github.com/labstack/echo/engine/standard"
	"github.com/labstack/echo/middleware"
	"gopkg.in/olahol/melody.v1"
	"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().(*standard.Response).ResponseWriter, c.Request().(*standard.Request).Request, "index.html")
		return nil
	})

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

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

	e.Run(standard.New(":5000"))
}

Example: gophers

package main

import (
	"github.com/gin-gonic/gin"
	"gopkg.in/olahol/melody.v1"
	"net/http"
	"strconv"
	"strings"
	"sync"
)

type GopherInfo struct {
	ID, X, Y string
}

func main() {
	router := gin.Default()
	mrouter := melody.New()
	gophers := make(map[*melody.Session]*GopherInfo)
	lock := new(sync.Mutex)
	counter := 0

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

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

	mrouter.HandleConnect(func(s *melody.Session) {
		lock.Lock()
		for _, info := range gophers {
			s.Write([]byte("set " + info.ID + " " + info.X + " " + info.Y))
		}
		gophers[s] = &GopherInfo{strconv.Itoa(counter), "0", "0"}
		s.Write([]byte("iam " + gophers[s].ID))
		counter += 1
		lock.Unlock()
	})

	mrouter.HandleDisconnect(func(s *melody.Session) {
		lock.Lock()
		mrouter.BroadcastOthers([]byte("dis "+gophers[s].ID), s)
		delete(gophers, s)
		lock.Unlock()
	})

	mrouter.HandleMessage(func(s *melody.Session, msg []byte) {
		p := strings.Split(string(msg), " ")
		lock.Lock()
		info := gophers[s]
		if len(p) == 2 {
			info.X = p[0]
			info.Y = p[1]
			mrouter.BroadcastOthers([]byte("set "+info.ID+" "+info.X+" "+info.Y), s)
		}
		lock.Unlock()
	})

	router.Run(":5000")
}

More examples

Documentation

Contributors

• Ola Holmström (@olahol)
• Shogo Iwano (@shiwano)
• Matt Caldwell (@mattcaldwell)
• Heikki Uljas (@huljas)
• Robbie Trencheny (@robbiet480)
• yangjinecho (@yangjinecho)

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 }