How to develop real-time notification function using golang's Websocket

How to use Golang's Websocket to develop real-time notification functions

Overview:
Websocket is a technology that enables two-way communication between the client and the server. It can realize real-time data transmission and timely notification functions. This article will introduce how to use Golang's Websocket library to develop real-time notification functions and provide specific code examples.

1. Install the Websocket library
First, we need to install Golang’s Websocket library. Execute the following command in the command line:

go get github.com/gorilla/websocket

2. Establish Websocket connection
In Golang, we can use the gorilla/websocket library to establish a Websocket connection. First, we need to import the library:

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

Then, we can define a websocket.Upgrader object to upgrade the HTTP connection to a Websocket connection and specify some options:

var upgrader = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
}

Next, we can define a processing function to handle Websocket connection requests:

func websocketHandler(w http.ResponseWriter, r *http.Request) {
    // 升级HTTP连接为Websocket连接
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        // 处理连接错误
        log.Println(err)
        return
    }
    
    // 在此处处理Websocket连接
    defer conn.Close()
    
    // 循环接收和发送消息
    for {
        // 读取消息
        _, message, err := conn.ReadMessage()
        if err != nil {
            // 处理读取错误
            log.Println(err)
            break
        }
        
        // 处理接收到的消息
        log.Println(string(message))
        
        // 发送消息
        err = conn.WriteMessage(websocket.TextMessage, message)
        if err != nil {
            // 处理写入错误
            log.Println(err)
            break
        }
    }
}

We can register this processing function on a specific path to handle Websocket connection requests. For example, we can register it on the /websocket path:

http.HandleFunc("/websocket", websocketHandler)

Finally, we need to start an HTTP server to listen for Websocket connection requests:

log.Fatal(http.ListenAndServe(":8080", nil))

3. Client Side implementation
On the client side, we can use the browser's JavaScript to establish a Websocket connection and communicate. The following is a simple example:

var socket = new WebSocket("ws://localhost:8080/websocket");

socket.onopen = function(event) {
    console.log("Websocket connected.");
}

socket.onmessage = function(event) {
    console.log("Received message:", event.data);
}

socket.onclose = function(event) {
    console.log("Websocket closed.");
}

// 发送消息
socket.send("Hello, server!");

In this example, we first create a WebSocket object and specify the connection URL. We can then handle the logic of connection establishment, message reception, and disconnection in the onopen, onmessage, and onclose event handlers. Finally, we can use the send method to send messages to the server.

4. Using the real-time notification function
Through the above steps, we have successfully established a Websocket connection and implemented basic communication functions. Now, we can use this connection to implement real-time notification functionality. For example, we can send notification messages to the client regularly on the server side:

func sendNotification(conn *websocket.Conn, message string) {
    // 发送消息
    err := conn.WriteMessage(websocket.TextMessage, []byte(message))
    if err != nil {
        log.Println(err)
    }
}

We can put the above sendNotification function in a scheduled task according to our own needs, and regularly send notification messages to the client. Send notification messages to the end.

5. Summary
Using Golang’s Websocket library can easily implement real-time notification functions. By establishing a Websocket connection, we can achieve two-way communication and send notification messages on the server side to the client. This article explains how to use Golang's Websocket library to establish a Websocket connection and how to communicate on the client and server sides. Hope this article is helpful to you.

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