WebSocket

WebSocket ให้ full-duplex communication ระหว่าง client และ server

gorilla/websocket (ยอดนิยม)

go get github.com/gorilla/websocket

package main

import (
    "fmt"
    "log"
    "net/http"

    "github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
    // ระวัง: อย่าใช้ใน production แบบนี้
    CheckOrigin: func(r *http.Request) bool { return true },
}

func wsHandler(w http.ResponseWriter, r *http.Request) {
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        log.Println("Upgrade error:", err)
        return
    }
    defer conn.Close()

    for {
        // Read message
        messageType, message, err := conn.ReadMessage()
        if err != nil {
            log.Println("Read error:", err)
            break
        }

        log.Printf("Received: %s", message)

        // Echo back
        response := fmt.Sprintf("Echo: %s", message)
        err = conn.WriteMessage(messageType, []byte(response))
        if err != nil {
            log.Println("Write error:", err)
            break
        }
    }
}

func main() {
    http.HandleFunc("/ws", wsHandler)
    log.Println("Server starting on :8080")
    log.Fatal(http.ListenAndServe(":8080", nil))
}