How can I make my server.php run continually?

Question

So I have this server code and it works with my client. But it gets one message from the client and sends a message back reversed. Here is the code: SERVER.php

<?php 

    $host = "127.0.0.1"; 
    $port = 1234; 

    // 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) or 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, 1024) or die("Could not read input\n"); 

    // clean up input string 
    $input = trim($input); 

    // reverse client input and send back 
    $output = strrev($input) . "\n"; 
    socket_write($spawn, $output, strlen ($output)) or die("Could not write output\n"); 

    // close sockets 
    socket_close($spawn); 
    socket_close($socket); 

?>

How can I edit this code so it can run continually? The client does not have to stay up of course, it will just open a new socket, send a message, get it back from server and close the socket. Next time I want to send a message, I will do the previous step again.

Now if i send a message and get a respond from server, they both close the socket. Please help me to modify the server side so that it will not close the socket and wait for a new connection.

I tried to add a while loop but as soon the client closes, the server closes again saying that it could not read from client anymore.

Thanks

Answer 1

I figured it out. Most of you were close to solving it like I was by using while() loop. But you cannot just put your code inside the while and expect it to work. The right way of doing it is as follows:

<?php 
$host = "127.0.0.1"; 
$port = 1234; 

// 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"); 
    while(true) {
    // start listening for connections 
    $result = socket_listen($socket, 3) or 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, 1024) or die("Could not read input\n"); 

    // clean up input string 
    $input = trim($input); 

    // reverse client input and send back 
    $output = strrev($input) . "\n"; 
    socket_write($spawn, $output, strlen ($output)) or die("Could not write output\n"); 
    }
// close sockets 
socket_close($spawn); 
socket_close($socket); 

?>

If you try to put the while any other place it will introduce an error. Thanks everyone for help :D

Answer 2

After the accept you need to fork - see here http://php.net/manual/en/function.pcntl-fork.php

The accept needs to be in a loop. After accept fork a process to handle that client.

ie

while (TRUE)
{
    $spawn = socket_accept($socket) or die("Could not accept incoming connection\n"); 

    $pid = pcntl_fork();
    if ($pid == -1) {
         die('could not fork');
    } else if ($pid) {
         // we are the parent
         socket_close($spawn);
    } else {
         // we are the child
         // Use $spawn for communication as you see fit
         // exit();
    }    
}

You will need to use signal handler to tidy up zombie processes.

Answer 3

The "brute" way is insert your code in a infinite loop.

While(1){
     .
     .
 }

Other way, after received your message, you can recurseively call your script.

Answer 4

  while( TRUE ) {

      // your code


  }