使用现有的PHP套接字

Question

this is my first post to the forum so apologies for any newbie mistakes...

I have a php script the opens a streaming socket to the server, sends a request and waits for the response message(s). The script looks like this:

---

<?php
$addr="192.168.1.1";
$port=6010;

$sock = fsockopen("tcp://$addr:$port", $errno, $errstr, $timeout) or die("socket problem");
stream_set_timeout($sock,30) or die("timeout not set");

$message='<?xml version="1.0" encoding="UTF-8"?><Request><Type>1</Type></Request>'

$slen=pack("N",strlen($message));

fwrite($sock,$slen.$message);

ob_flush();flush();

while((!feof($sock)) && (!$info['timed_out'])){
    $b3=fread($sock,3);
    $b4=fread($sock,1);
    $temp=unpack("N",$b3.$b4);
    $length=$temp[1];
    $lines=fread($sock,$length);
    if($lines){
        if(preg_match("'<Response>(.*?)</Response>'",$lines, $match)){
            if($match){
                $content=$match[1];
                echo nl2br($content);
            }
        }
    }
    $info = stream_get_meta_data($sock);
}
fclose($sock);
?>

---

Above script works well, but I would like to add there functionality (a cancel -button) to exit the while loop and send cancellation message to the server using the same socket, e.g. Type 0

The problem is that submit will refresh the page and loose current $sock.

Any ideas or simple solution would be highly appreciated.

Thanks. T.

Answer 1

Elaborating on what @Scuzzy suggests, one option can be to have the "Cancel Button" calling asynchronously to another php script. This would set a flag on file/disk/database (your choice) indicating that user asked to Cancel.

Async call will preserve the session on the main php script.

In the main loop here, you periodically check for that flag status, and exit immediately if the flag is set, performing additional cleanup if needed.

The pseudo-code for the main loop would be:

<?php
/*
   All the initialization
*/

cancelOperation = False;
while((!feof($sock)) && (!$info['timed_out'])){
    $b3=fread($sock,3);
    $b4=fread($sock,1);
    $temp=unpack("N",$b3.$b4);
    $length=$temp[1];
    $lines=fread($sock,$length);
    if($lines){
        if(preg_match("'<Response>(.*?)</Response>'",$lines, $match)){
            if($match){
                $content=$match[1];
                echo nl2br($content);
            }
        }
    }
    $info = stream_get_meta_data($sock);

    // Now check external condition, from either file or db for example
    cancelOperation = checkExternalCondition();
    if (cancelOperation === True) {
        break;
    }
}
if (cancelOperation === True) {
    // additional cleanup needed goes here.
}
fclose($sock);
?>