code: Add server implementation example code

code/hub.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"strings"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+type message struct {
+	Sender  string    `json:"sender"`
+	Content string    `json:"content"`
+	Date    time.Time `json:"date"`
+}
+
+func (m message) dispatch() {
+	for client := range connections {
+		client.WriteJSON(m)
+	}
+}
+
+var connections = make(map[*websocket.Conn]string)
+
+func sendChatMessage(sender *websocket.Conn, msg string) {
+	m := message{
+		Sender:  connections[sender],
+		Content: msg,
+		Date:    time.Now().UTC(),
+	}
+	m.dispatch()
+}
+
+func handleDisconnection(sender *websocket.Conn) {
+	m := message{
+		Sender:  "server",
+		Content: connections[sender] + " has left the chat",
+		Date:    time.Now().UTC(),
+	}
+	m.dispatch()
+	delete(connections, sender)
+}
+
+func handleIncomingMessage(sender *websocket.Conn, msg string) {
+	if _, ok := connections[sender]; !ok {
+		connections[sender] = strings.TrimSpace(msg)
+
+		m := message{
+			Sender:  "server",
+			Content: msg + " has joined the chat",
+			Date:    time.Now().UTC(),
+		}
+		m.dispatch()
+		return
+	}
+
+	sendChatMessage(sender, msg)
+}

code/main.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+var (
+	upgrader = websocket.Upgrader{
+		ReadBufferSize:  1024,
+		WriteBufferSize: 1024,
+	}
+)
+
+func websocketConnection(w http.ResponseWriter, r *http.Request) {
+	ws, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		fmt.Fprintf(w, "Internal server error: %s", err)
+		fmt.Printf("Internal server error: %s", err)
+		return
+	}
+
+	defer ws.Close()
+
+	ws.WriteMessage(websocket.TextMessage, []byte("nickname"))
+
+	for {
+		_, p, err := ws.ReadMessage()
+		if err != nil {
+			handleDisconnection(ws)
+			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
+				log.Printf("error: %v", err)
+			}
+			break
+		}
+
+		msg := string(p)
+		handleIncomingMessage(ws, msg)
+	}
+}
+
+func main() {
+	http.HandleFunc("/websocket", websocketConnection)
+	http.Handle("/", http.FileServer(http.Dir("./static")))
+
+	http.ListenAndServe(":8080", nil)
+}

code/static/index.html

@@ -0,0 +1 @@
+<p>sawp</p>