php: How to save the client socket (not closed), so a further script may retrieve it to send an answer?

Question

I have a client-server application, in which the server may require to send information back to clients.

As the client-server pattern does not allow the server to \"

Answer 1

One way to solve it - forget about sockets.

Pseudocode:

// receive request, set some session_id if not exists
// request contains last_timestamp, so we know which data client already have
// check have we any dataset for this session_id after last_timestamp
// return this dataset, or no_new_data signature

Data can be stored in database, for example.

Answer 2

So, you need two connections for each client, one persist for get data from server, and other to send data to.

Something like:

in persist.php:

$socket = stream_socket_server('unix:///tmp/unique.sock', $errno, $errstr);
if (!$socket) {
  echo "$errstr ($errno)<br />\n";
} else {
  while ($conn = stream_socket_accept($socket)) {
    $buffer = "";
    // Read until double CRLF
    while( !preg_match('/\r?\n\r?\n/', $buffer) )
        $buffer .= fread($client, 2046); 

    //Operate with our listener
    echo $buffer;
    flush();

    // Respond to socket client
    fwrite($conn,  "200 OK HTTP/1.1\r\n\r\n");
    fclose($conn);
  }
  fclose($socket);
}

in senddata.php:

$sock = stream_socket_client('unix:///tmp/unique.sock', $errno, $errstr);
fwrite($sock, $data);
fflush($sock);
fclose($sock);