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English
In PHP's CLI (command line interface) mode, the socket_accept() function can be used to handle low-level network connections. This allows us to build a simple TCP server using PHP to accept client requests and send responses. While PHP is not the preferred language for building web services in the traditional sense, it provides enough underlying APIs to allow us to easily experiment or build lightweight services.
Before establishing a network service, you need to understand the following PHP Socket functions:
socket_create() : Create a socket resource.
socket_bind() : binds the socket to the IP address and port.
socket_listen() : Listen to incoming connections.
socket_accept() : accepts connection request.
socket_read() / socket_write() : used to receive and send data.
socket_close() : Close the connection.
Here is an example of a simple PHP TCP server built using socket_accept() .
<?php
$host = "0.0.0.0";
$port = 9000;
// Create a socket
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($sock === false) {
die("socket_create() failed: " . socket_strerror(socket_last_error()) . "\n");
}
// Bind to address and port
if (!socket_bind($sock, $host, $port)) {
die("socket_bind() failed: " . socket_strerror(socket_last_error($sock)) . "\n");
}
// Start monitoring
if (!socket_listen($sock, 5)) {
die("socket_listen() failed: " . socket_strerror(socket_last_error($sock)) . "\n");
}
echo "The server is started，Listen to port $port...\n";
while (true) {
// Accept a connection
$client = socket_accept($sock);
if ($client === false) {
echo "socket_accept() failed: " . socket_strerror(socket_last_error($sock)) . "\n";
continue;
}
// Read client request
$input = socket_read($client, 1024);
echo "Received a request：" . trim($input) . "\n";
// Construct the response content
$response = "Welcome to visit m66.net Testing services！What you sent is：$input\n";
// Write back to the client
socket_write($client, $response, strlen($response));
// Close client connection
socket_close($client);
}
// Close the main socket（In theory, it will never be executed here）
socket_close($sock);
Save the above code as server.php and run it through the command line:
php server.php
This script will listen to port 9000 and wait for the client to connect. You can use telnet or other TCP client tools to connect to the server:
telnet 127.0.0.1 9000
After entering any text and pressing, the server will echo the text with a welcome message.
Please make sure PHP has sockets extension enabled (can be checked via php -m ).
The service is single threaded and can only process one connection at a time. If multiple connections need to be processed concurrently, you can use pcntl_fork() or use more professional services such as Swoole.
Do not use such a simple implementation in production environments, as it does not have any security and fault tolerance.
Although PHP is not the main language for network service development, such socket services can be used for:
Simple debugging tool
LAN data transmission and reception services
Prototyping of custom protocols
Exchange of data with non-Web systems (such as hardware devices)
