Detailed introduction to php Socket programming

PHP uses Berkeley's socket library to create its connection. You can know that socket is just a data structure. You use this socket data structure to start a session between the client and the server. This server is always listening and preparing to generate a new session. When a client connects to the server, it opens a port on which the server is listening for a session. At this time, the server accepts the client's connection request, and then performs a loop. Now the client can send information to the server, and the server can send information to the client.
To generate a Socket, you need three variables: a protocol, a socket type and a public protocol type. There are three protocols to choose from when generating a socket. Continue reading below to get detailed protocol content.
Defining a public protocol type is an essential element for connection

Let us start with a simple example --- a string that receives input characters , processes and Return this string to the client's TCP service. The code is as follows:

<?php
// 设置一些基本的变量 
$host = "192.168.1.99"; 
$port = 1234; 
// 设置超时时间 
set_time_limit(0); 
// 创建一个Socket 
$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die("Could not create 
socket\n"); 
//绑定Socket到端口 
$result = socket_bind($socket, $host, $port) or die("Could not bind to 
socket\n"); 
// 开始监听链接 
$result = socket_listen($socket, 3) or die("Could not set up socket 
listener\n"); 
// accept incoming connections 
// 另一个Socket来处理通信 
$spawn = socket_accept($socket) or die("Could not accept incoming 
connection\n"); 
// 获得客户端的输入 
$input = socket_read($spawn, 1024) or die("Could not read input\n"); 
// 清空输入字符串 
$input = trim($input); 
//处理客户端输入并返回结果 
$output = strrev($input) . "\n"; 
socket_write($spawn, $output, strlen ($output)) or die("Could not write 
output\n"); 
// 关闭sockets 
socket_close($spawn); 
socket_close($socket); 
?>

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