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Echo

WebSocket

Los handlers de Echo pueden servir conexiones WebSocket actualizando la conexión HTTP subyacente. Esta receta muestra dos enfoques: el paquete estándar golang.org/x/net/websocket y la biblioteca popular gorilla/websocket.

Usar net WebSocket

Sección titulada «Usar net WebSocket»

Servidor

Sección titulada «Servidor»
package main


import (
  "context"
  "fmt"


  "github.com/labstack/echo/v5"
  "github.com/labstack/echo/v5/middleware"
  "golang.org/x/net/websocket"
)


func hello(c *echo.Context) error {
  websocket.Handler(func(ws *websocket.Conn) {
    defer ws.Close()
    for {
      // Write
      if err := websocket.Message.Send(ws, "Hello, Client!"); err != nil {
        c.Logger().Error("failed to write WS message", "error", err)
      }


      // Read
      msg := ""
      if err := websocket.Message.Receive(ws, &msg); err != nil {
        c.Logger().Error("failed to write WS message", "error", err)
      }
      fmt.Printf("%s\n", msg)
    }
  }).ServeHTTP(c.Response(), c.Request())
  return nil
}


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


  e.Use(middleware.RequestLogger())
  e.Use(middleware.Recover())


  e.Static("/", "../public")
  e.GET("/ws", hello)


  sc := echo.StartConfig{Address: ":1323"}
  if err := sc.Start(context.Background(), e); err != nil {
    e.Logger.Error("failed to start server", "error", err)
  }
}

Usar gorilla WebSocket

Sección titulada «Usar gorilla WebSocket»

Servidor

Sección titulada «Servidor»
package main


import (
  "context"
  "fmt"


  "github.com/gorilla/websocket"
  "github.com/labstack/echo/v5"
  "github.com/labstack/echo/v5/middleware"
)


var (
  upgrader = websocket.Upgrader{}
)


func hello(c *echo.Context) error {
  ws, err := upgrader.Upgrade(c.Response(), c.Request(), nil)
  if err != nil {
    return err
  }
  defer ws.Close()


  for {
    // Write
    err := ws.WriteMessage(websocket.TextMessage, []byte("Hello, Client!"))
    if err != nil {
      c.Logger().Error("failed to write WS message", "error", err)
    }


    // Read
    _, msg, err := ws.ReadMessage()
    if err != nil {
      c.Logger().Error("failed to read WS message", "error", err)
    }
    fmt.Printf("%s\n", msg)
  }
}


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


  e.Use(middleware.RequestLogger())
  e.Use(middleware.Recover())


  e.Static("/", "../public")


  e.GET("/ws", hello)


  sc := echo.StartConfig{Address: ":1323"}
  if err := sc.Start(context.Background(), e); err != nil {
    e.Logger.Error("failed to start server", "error", err)
  }
}

Cliente

Sección titulada «Cliente»
<!doctype html>
<html lang="en">


<head>
  <meta charset="utf-8">
  <title>WebSocket</title>
</head>


<body>
  <p id="output"></p>


  <script>
    var loc = window.location;
    var uri = 'ws:';


    if (loc.protocol === 'https:') {
      uri = 'wss:';
    }
    uri += '//' + loc.host;
    uri += loc.pathname + 'ws';


    ws = new WebSocket(uri)


    ws.onopen = function() {
      console.log('Connected')
    }


    ws.onmessage = function(evt) {
      var out = document.getElementById('output');
      out.innerHTML += evt.data + '<br>';
    }


    setInterval(function() {
      ws.send('Hello, Server!');
    }, 1000);
  </script>
</body>


</html>

Salida

Sección titulada «Salida»

Servidor

Ventana de terminal
Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!

Cliente

Ventana de terminal
Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!