Php读取套接字流更新

I connect to an application for a push/stream data.

With the following code I have a right answer from the app (outcome=OK|item=THEITEM) but can't figure out how to get the var "last_value" and its updates. The loop is commented out, I have no echo with it (loop)

$port = ('5333');  
$address = ('127.0.0.1');   
$fp = stream_socket_client("tcp://$address:$port", $errno, $errstr, 1);  
if (!$fp) {  
    echo "$errstr ($errno)<br />
";  
} else {    
    $in = "function=subscribe|item=THEITEM|schema=last_value";  
    fwrite($fp, $in."
");  
    //while (!feof($fp)) {  
        echo fgets($fp, 1024);  
    //}  
    fclose($fp);  
}  

This returns outcome=OK|item=THEITEM. The updates should be like THEITEM|last_value.