How to resolve the algorithm Hello world/Web server step by step in the PHP programming language

Published on 12 May 2024 09:40 PM
#Php

How to resolve the algorithm Hello world/Web server step by step in the PHP programming language

Table of Contents

Problem Statement

The browser is the new GUI !

Serve our standard text   Goodbye, World!   to   http://localhost:8080/   so that it can be viewed with a web browser. The provided solution must start or implement a server that accepts multiple client connections and serves text as requested. Note that starting a web browser or opening a new window with this URL is not part of the task. Additionally, it is permissible to serve the provided page as a plain text file (there is no requirement to serve properly formatted HTML here). The browser will generally do the right thing with simple text like this.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Hello world/Web server step by step in the PHP programming language

The code provided serves static web pages using PHP sockets. Let's break down each part:

  1. Socket Creation:
  • socket_create(AF_INET, SOCK_STREAM, 0): This function creates a socket. Here's what it does:
    • AF_INET specifies that the socket will use IPv4 (Internet Protocol version 4). For IPv6, you would use AF_INET6.
    • SOCK_STREAM specifies that the socket will be a TCP socket for reliable, connection-oriented communication.
    • The last parameter (0) is for the socket protocol. It is 0 for the default system protocol for TCP.
  1. Socket Binding:
  • socket_bind($socket, 0, 8080): This function binds the socket to an IP address and port. Here, it binds the socket to all available IP addresses (0) and port 8080, which is the standard port for HTTP traffic.
  1. Socket Listening:
  • socket_listen($socket): This function puts the socket in listening mode. It waits for incoming client connections.
  1. Response Message:
  • The code defines the $msg variable, which contains HTML content that will be sent as a response to clients. It's a basic HTML document with the text "Goodbye, world!"
  1. Infinite Loop for Client Handling:
  • The code enters an infinite loop using for (;;). Inside the loop:
    • @socket_accept($socket): This function accepts any incoming client connections. If there is no connection, it returns false, and the script continues with the usleep function.
    • If a connection is accepted, it proceeds to send the response.
    • socket_write sends the predefined $msg as a response to the client. The response includes an HTTP header with status code 200 OK, content length, and content type.
  1. Limiting CPU Usage:
  • After each client request is handled, the script uses usleep(100000) to sleep for 100,000 microseconds (0.1 seconds). This limits CPU usage by preventing the script from continuously checking for new connections.

Overall, this PHP code creates a basic web server that listens for client requests on port 8080. When a client connects, it sends a pre-defined HTML response. The loop continues indefinitely until manually terminated.

Source code in the php programming language

<?php
                     // AF_INET6 for IPv6  // IP
$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die('Failed to create socket!');
                  // '127.0.0.1' to limit only to localhost // Port
socket_bind($socket, 0,                                        8080);
socket_listen($socket);

$msg = '<html><head><title>Goodbye, world!</title></head><body>Goodbye, world!</body></html>';

for (;;) {
    // @ is used to stop PHP from spamming with error messages if there is no connection
    if ($client = @socket_accept($socket)) {
        socket_write($client, "HTTP/1.1 200 OK\r\n" .
               "Content-length: " . strlen($msg) . "\r\n" .
               "Content-Type: text/html; charset=UTF-8\r\n\r\n" .
               $msg);
    }
    else usleep(100000); // limits CPU usage by sleeping after doing every request
}
?>

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