c3cris c3cris - 4 months ago 57
Ajax Question

Have a PHP server script persistently listen on a socket non blocking?

I am writing a project that is in 2 parts.

So far I have a front end View.php (HTML5,CSS3,JQuery) and this will query the server.php

The server PHP opens a TCP socket to a server and listens in and can make commands by writing to the socket.

The normal procedure now goes like this

View.php -> Calls using rest API to server.php
Server.php -> Connects to TCP -> Reads from TCP -> Json_encodes & print -> close TCP socket connection.


What I want to achieve is a script Server.php that once started. It constantly listens in to a server, until it gets a shutdown command. I want to keep a fsocket connection open. Any thoughts?

Answer

The answer is using non blocking programming. In PHP we have specific function for non blocking I/O. For sockets you should use socket_set_nonblock function on a socket resource.

$port = 8081;
$address = '127.0.0.1';

if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) {
    echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
    exit();
}
if (socket_bind($sock, $address, $port) === false) {
    echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
    exit();
}
if (socket_listen($sock, 5) === false) {
    echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
}
socket_set_nonblock($sock);
echo "listening for new connection".PHP_EOL;
$conneted_clients = [];

do {
   $clientsock = socket_accept($sock);
   if($clientsock !== false){

        socket_set_nonblock($clientsock);
        $conneted_clients[] = $clientsock;
        socket_getpeername($clientsock,$address);
        echo "New Connection from: ".$address.PHP_EOL;

        $msg = PHP_EOL."Welcome to the PHP Test Server. " . PHP_EOL.
        "To quit, type 'quit'. To shut down the server type 'shutdown'." . PHP_EOL;

        socket_write($clientsock, $msg, strlen($msg));
    }
    $status = check_clients($conneted_clients);

    if(!$status) break;
    usleep(500000);
} while (true);

function check_clients($clients)
{
    foreach($clients as $key => $con)
    {
        if(get_resource_type($con) !== "Socket")
        {   
            socket_getpeername($clientsock,$address);
            echo $address." has diconnected.".PHP_EOL;
            unset($clients[$key]);
            continue;
        }
        if (false === $buff = socket_read($con, 2048)) {
            continue;
        }

        $buff = trim($buff);

        if ($buff == 'quit') {
            socket_close($con);
            unset($clients[$key]);
            continue;
        }
        if (trim($buff) == 'shutdown') {
            socket_close($con);
            echo "shutdown initiated".PHP_EOL;
            return FALSE;
        }
        if($buff != false || $buff != null)
        {
            $talkback = "PHP: You said '$buff'.".PHP_EOL;
            socket_write($con, $talkback, strlen($talkback));
            echo "$buff".PHP_EOL;
        }
    }
    return TRUE;
}
echo "Closing Server";
socket_close($sock);