Go Gorilla WebSocket
last modified April 11, 2024
In this article we show how to work with websockets using Gorilla WebSocket package.
$ go version go version go1.22.2 linux/amd64
We use Go version 1.22.2.
WebSocket is a computer communications protocol, providing full-duplex communication channels over a single TCP connection. WebSockets are used in highly interactive applications such as games, chats, or stock markets.
The Gorilla WebSocket package provides a complete and tested implementation of the WebSocket protocol.
$ go get github.com/gorilla/websocket
This command installs the package.
Gorilla WebSocket example
In the example, we create a simple websocket server. The client will be a browser that connects to the server with JS code.
package main
import (
"fmt"
"log"
"net/http"
"github.com/gorilla/websocket"
)
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
func main() {
http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
conn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
log.Fatal(err)
}
for {
msgType, msg, err := conn.ReadMessage()
if err != nil {
return
}
fmt.Printf("%s sent: %s\n", conn.RemoteAddr(), string(msg))
if err = conn.WriteMessage(msgType, msg); err != nil {
return
}
}
})
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "index.html")
})
log.Println("Listening...")
log.Fatal(http.ListenAndServe(":8080", nil))
}
The program sets up the websocket endpoint and a static index.html page.
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
We define buffers for the upgrader. It specifies parameters for upgrading an HTTP connection to a WebSocket connection.
http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
We register a handler function for the /echo endpoint.
conn, err := upgrader.Upgrade(w, r, nil)
We upgrade the HTTP server connection to the WebSocket protocol.
for {
msgType, msg, err := conn.ReadMessage()
if err != nil {
return
}
fmt.Printf("%s sent: %s\n", conn.RemoteAddr(), string(msg))
if err = conn.WriteMessage(msgType, msg); err != nil {
return
}
}
We continually listen for any incoming messages sent through that WebSocket
connection. We read the message from the client with ReadMessage.
The WriteMessage writes the message back to the client.
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "index.html")
})
We set up the static HTML home page, from which we connect to the server.
The connection to the websocket endpoint is made from the browser.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<input id="input" type="text">
<button onclick="send()">Send</button>
<pre id="output"></pre>
<script>
var input = document.getElementById("input");
var output = document.getElementById("output");
var socket = new WebSocket("ws://localhost:8080/echo");
socket.onopen = () => {
output.innerHTML += "connected\n";
};
socket.onmessage = (e) => {
output.innerHTML += `{e.data}\n`;
};
function send() {
socket.send(input.value);
input.value = "";
}
</script>
</body>
</html>
In JS, we use the WebSocket class provides the API for creating and
managing a WebSocket connection to a server, as well as for sending and
receiving data on the connection.
Source
Gorilla Websocket - Github page
In this article we have worked with websockets using Gorilla WebSocket package.
Author
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