add implementation with server sent events

index.html

@@ -8,17 +8,37 @@
           <button onclick="websocket()">Listen</button>
       </div>
 
+      <div>
+          <h2>Server Sent Event</h2>
+          <p>Progress: <span id="sse"></span></p>
+          <button onclick="sse()">Listen</button>
+      </div>
+
       <script>
        function websocket() {
          var socket = new WebSocket({{ .websocket }}, "protocolOne");
          socket.onmessage = function (event) {
-           if (event.data === "done") {
+           if (event.data === "100") {
              document.getElementById("websocket").innerHTML = "done!";
              socket.close();
              return;
            }
            document.getElementById("websocket").innerHTML=event.data+"%";
-         }
+         };
+       }
+
+       function sse() {
+         document.getElementById("sse").innerHTML = "done!";
+         var source = new EventSource({{ .sse }});
+         source.onmessage = function(event) {
+           console.log("truc");
+           if (event.data === "100") {
+             document.getElementById("sse").innerHTML = "done!";
+             source.close();
+             return;
+           }
+           document.getElementById("sse").innerHTML=event.data+"%";
+         };
        }
       </script>
   </body>

ms.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"io"
 	"math/rand"
 	"net/http"
 	"os"
@@ -26,11 +27,13 @@ func main() {
 	router.GET("/", func(c *gin.Context) {
 		c.HTML(http.StatusOK, "index.html", gin.H{
 			"websocket": "ws://localhost:" + port + "/ws",
+			"sse":       "http://localhost:" + port + "/sse",
 		})
 	})
 	router.GET("/ws", websocketHandler(websocket.Upgrader{
 		Subprotocols: []string{"protocolOne"},
 	}))
+	router.GET("/sse", serverSentEventHandler())
 
 	router.Run(":" + port)
 }
@@ -43,20 +46,55 @@ func websocketHandler(upgrader websocket.Upgrader) func(c *gin.Context) {
 			return
 		}
 
-		progress := 0
-		for progress < 100 {
+		t := task{}
+		t.start()
+		for {
+			progress, ok := <-t.progress
+			if !ok {
+				break
+			}
+
 			if err := conn.WriteMessage(1, []byte(strconv.Itoa(progress))); err != nil {
 				c.AbortWithError(http.StatusInternalServerError, err)
 				return
 			}
-
-			progress += rand.Intn(2)
-			time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
 		}
+	}
+}
 
-		if err := conn.WriteMessage(1, []byte("done")); err != nil {
-			c.AbortWithError(http.StatusInternalServerError, err)
-			return
-		}
+func serverSentEventHandler() func(c *gin.Context) {
+	return func(c *gin.Context) {
+		t := task{}
+		t.start()
+
+		c.Stream(func(w io.Writer) bool {
+			progress, ok := <-t.progress
+			if !ok {
+				return false
+			}
+
+			c.SSEvent("", strconv.Itoa(progress))
+			return true
+		})
 	}
 }
+
+type task struct {
+	progress chan int
+}
+
+func (t *task) start() {
+	t.progress = make(chan int)
+	go func() {
+		p := 0
+		t.progress <- p
+		for p < 100 {
+			if rand.Intn(100) > 50 {
+				p++
+				t.progress <- p
+			}
+			time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
+		}
+		close(t.progress)
+	}()
+}