Golang implements long connection-Golang-php.cn

With the development of the Internet, long connection technology has gradually been applied in network communications. In practical applications, we may need to maintain a long-term communication connection with the client. In this case, we need to use long connection technology. As a popular programming language, golang's concurrency and high performance make it an excellent choice for implementing long connections. This article will introduce how to use golang to implement long connections.

1. What is a long connection?

A long connection means that after the client establishes a connection with the server, it can continuously transmit multiple data packets. In this connection, the server will not disconnect, but will always wait for new requests from the client and respond. This transmission method is widely used in network communications, such as instant messaging, server push data, etc.

Compared with short connections, the advantage of long connections is that it reduces the time and resource overhead of establishing and disconnecting connections, while improving the efficiency and real-time nature of data transmission.

2. How to implement long connections in golang

There are three main ways to implement long connections in golang:

Use TCP long connections

Using TCP long connections to implement long connections is the most common and simple way in golang. First create a TCP connection, then transfer data in the connection, and then the connection can be maintained until the connection is closed. The following demonstrates the basic code for using a long TCP connection:

package main

import (
    "fmt"
    "net"
)

func main() {
   serverAddr := "127.0.0.1:8888"
   conn, err := net.Dial("tcp", serverAddr)
   if err != nil {
       fmt.Println(err)
   }

   for {
       data := []byte("hello world")
       _, err := conn.Write(data)
       if err != nil {
           fmt.Println(err)
           break
       }

       buf := make([]byte, 1024)
       _, err = conn.Read(buf)
       if err != nil {
           fmt.Println(err)
           break
       }

       fmt.Println(string(buf))
   }
}

Copy after login

In this example, we create a TCP connection through the net.Dial() function, and then use conn. Write()Send data to the server, conn.Read()Read data from the connection. Use a for loop to keep the connection continuous.

Use WebSocket long connection

WebSocket is a communication protocol for full-duplex communication on a single TCP connection, providing a An event-based interaction method. In golang, you can use the third-party library gorilla/websocket to implement WebSocket long connections. Let's take a look at the code for using WebSocket to implement long connections:

package main

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

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

func echo(w http.ResponseWriter, r *http.Request) {
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        log.Println(err)
        return
    }
    for {
        messageType, p, err := conn.ReadMessage()
        if err != nil {
            log.Println(err)
            break
        }
        log.Println(string(p))
        if err = conn.WriteMessage(messageType, p); err != nil {
            log.Println(err)
            break
        }
    }
}

func main() {
    http.HandleFunc("/echo", echo)
    err := http.ListenAndServe(":8080", nil)
    if err != nil {
        log.Fatal(err)
    }
}

Copy after login

In this example, we use Upgrader to upgrade the HTTP connection to a WebSocket connection, and then use conn. ReadMessage() and conn.WriteMessage()transmit data in the connection. Use a for loop to keep the connection continuous.

Use HTTP long connection

HTTP long connection is a long connection technology based on the HTTP protocol. Compared with TCP persistent connection, HTTP persistent connection requires establishing an HTTP connection, and then data can be transmitted continuously through this connection. In golang, you can use the net/http library to implement HTTP long connections. The following demonstrates how to use HTTP long connections:

package main

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

func handler(w http.ResponseWriter, r *http.Request) {
    if r.Method != "GET" {
        http.Error(w, "Method not allowed", 405)
        return
    }
    fmt.Fprintf(w, "HTTP/1.1 200 OK
")
    fmt.Fprintf(w, "Content-Type: text/plain
")
    fmt.Fprintf(w, "Connection: keep-alive
")
    fmt.Fprintf(w, "
")

    writer := bufio.NewWriter(w)
    for {
        _, err := writer.WriteString("hello world
")
        if err != nil {
            log.Println(err)
            break
        }
        writer.Flush()
    }
}

func main() {
    http.HandleFunc("/", handler)
    err := http.ListenAndServe(":8080", nil)
    if err != nil {
        log.Fatal(err)
    }
}

Copy after login

In this example, we set the Connection: keep-alive header in the HTTP response to keep the HTTP connection continuous, and then use bufio.NewWriter()Write data to the connection each time.

3. How to choose a suitable long connection method?

Although there are three ways to implement long connections in golang, you must choose the appropriate method according to actual needs. Here are some aspects that need attention:

TCP long connection

The advantage of using TCP long connection is that it is simple and direct, and can quickly realize long connection. However, TCP long connections are not encrypted during data transmission, and data packets need to be assembled manually every time. At the same time, a custom protocol is required to implement data packetization and asynchronous callback. It is suitable for scenarios where the amount of data is small and the number of connections is small.

WebSocket long connection

WebSocket long connection uses an asynchronous method to transmit data, supports the server to push data to the client, the data transmission is more flexible, and it also has automatic packet re- The ability to group packages. However, the WebSocket long connection needs to send an HTTP request during the first handshake, which is one more time than the TCP long connection request.

HTTP persistent connection

HTTP persistent connection needs to establish a TCP connection like a TCP persistent connection when establishing a connection for the first time, but it can be controlled through HTTP headers during data transmission Connection persistence, a connection can transmit multiple HTTP requests and responses. However, the communication efficiency of HTTP long connections is slightly lower than that of TCP long connections and WebSocket long connections.

4. Summary

This article introduces three ways for golang to implement long connections: TCP long connections, WebSocket long connections, and HTTP long connections. It also analyzes their respective advantages and applicable scenarios. In actual development, the appropriate method needs to be selected based on specific scenarios. Long-term connection technology has broad application prospects in practical applications. In the future, we will see the emergence of more efficient, reliable, and safe long-term connection technologies.

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