PHP Socket Programming Process detailed

PHP Socket Programming Process detailed

Sockets are used for interprocess communication. Interprocess communication is typically based on a client-server model. At this point, the client-server is an application that can interact with each other. The interaction between the client and the server requires a connection. Socket programming is responsible for establishing an interactive connection between applications.

In this article, we'll learn how to create a simple client-server with PHP. We will also learn how client applications can send messages to the server and how to accept messages from the server.

Using code

Purpose: To develop a client to send a string message to the server, and the service side reverses the same information back to the client.

PHP Server

1th Step: Set variables, such as "host" and "Port"

$host = "127.0.0.1"; $port = 5353;//No Timeout set_time_limit (0);

The port number can be any positive integer between 1024-65535.

2nd step: Create a socket

$socket = Socket_create (af_inet, sock_stream, 0) or die ("Could not create socket\n");

3rd step: Bind socket to port and host

The socket resource created is bound to the IP address and port number.

$result = Socket_bind ($socket, $host, $port) or Die ("Could not bind to socket\n");

4th step: Start the socket monitor

After binding to IP and ports, the server begins to wait for the client to connect. It waits until the connection is not connected.

$result = Socket_listen ($socket, 3) or Die ("Could not set up socket listener\n");

5th step: Accept the connection

This function will accept incoming connection requests from the built socket. After accepting the connection from the client socket, the function returns another socket resource, which is actually responsible for communicating with the corresponding client socket. The "$spawn" here is the socket resource responsible for communicating with the client socket.

$spawn = socket_accept ($socket) or Die ("Could not accept incoming connection\n");

So far, we've got the server socket ready, but in fact the script doesn't do anything. So in order to continue with this goal, we will read the client socket message and then reverse the received message and send it back to the client socket.

6th step: Read the message from the client socket

$input = Socket_read ($spawn, 1024x768) or Die ("Could not read input\n");

7th step: Reverse the message

$output = Strrev ($input). "\ n";

8th step: Send a message to the client socket

Socket_write ($spawn, $output, strlen ($output)) or Die ("Could not write output\n");

Close socket

Socket_close ($spawn); Socket_close ($socket);

This completes the service side. Now, let's learn how to create a PHP client.

PHP Client

The first two steps are the same as the service side.

1th Step: Set variables, such as "host" and "Port"

$host = "127.0.0.1"; $port = 5353;//No Timeout set_time_limit (0);

Note: The ports and hosts here should be the same as those defined in the server.

2nd step: Create a socket

$socket = Socket_create (af_inet, sock_stream, 0) or die ("Could not create socket\n");

3rd step: Connect to the server

$result = Socket_connect ($socket, $host, $port) or Die ("Could not connect toserver\n");

At this point, unlike the server, the client socket is not bound to the port and host. Instead, it connects to the server socket and waits for the connection from the client socket to be accepted. This step establishes the client socket connection to the server socket.

4th step: Write to the server socket

Socket_write ($socket, $message, strlen ($message)) or Die ("Could not send data to server\n");

In this step, the client socket data is sent to the server socket.

5th step: Read the response from the server

$result = Socket_read ($socket, 1024x768) or Die (' Could not read server response\n '); echo "Reply from server  :" $result;

6th step: Close the socket

Socket_close ($socket);

The complete code

Service side (server.php)

Set some variables$host = "127.0.0.1"; $port = 25003;//don ' t timeout!set_time_limit (0);//Create socket$socket = socket _create (af_inet, sock_stream, 0) or die ("Could not create socket\n");//bind socket to Port$result = Socket_bind ($socket, $host, $port) or Die ("Could not bind to socket\n");//start listening for connections$result = Socket_listen ($socket, 3) o R die ("Could not set up socket listener\n"),//Accept incoming connections//spawn another socket to handle communication$ Spawn = Socket_accept ($socket) or Die ("Could not accept incoming connection\n");//Read Client Input$input = Socket_read ($ Spawn, 1024x768) or Die ("Could not read input\n");//clean up input string$input = Trim ($input); echo "Client Message:". $inpu t;//reverse client input and send back$output = Strrev ($input). "\ n"; Socket_write ($spawn, $output, strlen ($output)) or Die ("Could not write output\n");//Close Socketssocket_close ($ Spawn); Socket_close ($socket);

Client (client.php)

$host    = "127.0.0.1"; $port    = 25003; $message = "Hello server"; echo "message to Server:" $message;//Create socket$ Socket = Socket_create (af_inet, sock_stream, 0) or die ("Could not create socket\n");//connect to Server$result = Socket_c Onnect ($socket, $host, $port) or Die ("Could not connect to server\n");  Send string to Serversocket_write ($socket, $message, strlen ($message)) or Die ("Could not send data to server\n");//Get Server Response$result = Socket_read ($socket, 1024x768) or Die (' Could not read server response\n '); echo "Reply from Server
   : ". $result;//Close Socketsocket_close ($socket);

After creating the above files (server.php and client.php), do the following:

1. Copy these files from the WWW directory (assuming wamp), and place them in C:\wamp.
2. Open a Web browser and type localhost in the address bar.
3. Browse server.php First and then client.php.

PHP Socket Programming Process detailed