How to use PHP's socket programming function?

PHP is a programming language widely used in web development and supports many network programming applications. Among them, Socket programming is a commonly used way to implement network communication. It allows programs to implement inter-process communication and transmit data through the network.

This article will introduce how to use Socket programming function in PHP.

1. Introduction to Socket Programming

Socket (socket) is an abstract concept. It represents an open port in network communication. A process needs to connect to the port in order to Exchange data with other processes.

Sockets are generally divided into two types: TCP Socket and UDP Socket. TCP Socket is suitable for reliable connection-oriented communication, and UDP Socket is suitable for connectionless communication, applications with relatively small data packets and sensitive to delay.

2. Socket programming using PHP

In PHP, using Socket programming requires calling the socket_create() function to create a Socket connection, then setting the Socket options as needed, and finally calling socket_connect() function or socket_bind() function to further connect or bind the address and port. Finally, call the socket_close() function to disconnect.

1. Create a Socket connection

The socket_create() function can create a Socket connection.

$socket = socket_create(AF_INET, SOCK_STREAM, 0);

The first parameter specifies the address family ipv4, and the second parameter specifies the Socket type as a streaming socket (Socket stream). The third parameter is generally 0, which means using the default protocol (TCP/IP).

2. Set Socket options

You can use the socket_set_option() function to set Socket options, such as setting reuse addresses.

socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);

Among them, the first parameter is the Socket connection resource, and the second parameter represents the Socket level. For example, setting the Socket option requires using SOL_SOCKET level. The third parameter specifies which option to set. Here, the SO_REUSEADDR option is set to 1Enable address reuse.

3. Connect or bind address and port

The socket_connect() function is used to connect to the remote Socket server, and the socket_bind() function is used to bind the local Socket server address and port.

For example, use the socket_bind() function to bind the local address 127.0.0.1 and port 8888.

socket_bind($socket, '127.0.0.1', 8888);

4. Listen for connection requests

Use the socket_listen() function to start listening for connection requests.

socket_listen($socket);

5. Receiving and sending data

Use the socket_accept() function to receive a connection request, and then perform data transfer operations, such as reading or writing data.

$client = socket_accept($socket);
$bytes = socket_recv($client, $data, 1024, 0);
socket_send($client, $data, $bytes, 0);

Among them, the socket_recv() function can be used to receive data. The first parameter is the Socket connection resource, the second parameter is used to store the received data, and the third parameter represents the maximum reading of data. Length, the fourth parameter is generally 0, which means the socket flag is not used.

The socket_send() function can be used to send data to the client.

6. Close the connection

Use the socket_close() function to close the connection.

socket_close($socket);

3. Sample code

The following is a simple complete sample code of Socket Server and Client for Socket communication.

Server side:

<?php
$host = "127.0.0.1";
$port = 8888;

// 创建Socket连接
$socket = socket_create(AF_INET, SOCK_STREAM, 0);

// 设置Socket选项
socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);

// 绑定本地地址和端口
if (!socket_bind($socket, $host, $port)) {
    echo "Socket bind failed!";
}

// 监听连接请求
socket_listen($socket);

// 接受连接请求
$client = socket_accept($socket);

// 读取数据
$msg = socket_read($client, 1024);

// 输出接收到的数据
echo "Received message: {$msg}";

// 向Client发送数据
$response = "Message from Server: Hi Client!";
socket_write($client, $response, strlen($response));

// 关闭连接
socket_close($client);
socket_close($socket);
?>

Client side:

<?php
$host = "127.0.0.1";
$port = 8888;

// 创建Socket连接
$socket = socket_create(AF_INET, SOCK_STREAM, 0);

// 连接到Server
if (!socket_connect($socket, $host, $port)) {
    echo "Socket connect failed!";
}

// 向Server发送数据
$message = "Hello Server!";
socket_write($socket, $message, strlen($message));

// 接收Server的响应
$response = socket_read($socket, 1024);

// 输出Server响应
echo "Received message: {$response}";

// 关闭连接
socket_close($socket);
?>

IV. Summary

This article introduces how to use Socket programming in PHP to achieve network communication, including Create a Socket connection, set Socket options, connect/bind Socket address and port, send/receive data, close Socket connection and other steps.

Socket programming is a very important and commonly used network programming technology, which enables processes to communicate on the network and realize data interoperability and exchange. I believe that through the introduction of this article, readers have a certain understanding and mastery of how to use Socket programming in PHP.

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