What are WebSockets?

WebSockets is a network communication protocol that provides a bidirectional, persistent, and full-duplex connection between a client (usually a browser) and a server over a single TCP socket.

Unlike traditional HTTP, where the client sends a request and the server responds and then the connection is closed, WebSocket establishes a persistent connection, allowing both parties to send data at any time without needing to re-establish the connection.

This is especially useful for real-time applications such as chats, online games, trading platforms, etc.

In Go, the gorilla/websocket library is often used for working with WebSocket. Here's an example of a simple server:

package main

import (
    "net/http"
    "github.com/gorilla/websocket"
    "log"
)

var upgrader = websocket.Upgrader{}

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

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

        err = conn.WriteMessage(messageType, message)
        if err != nil {
            log.Println("Write error:", err)
            break
        }
    }
}

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

This server accepts WebSocket connections and sends back the received messages as an echo.