Question

How to send the header to the client before execute the php scripts ?

My script take many time to finish and the client don’t receive anything through this period.

<?

header("HTTP/1.1 200 OK");
header("Date: Thu, 23 Jun 2011 10:16:31 GMT");
header("Content-Type: application/octet-stream");
header("Content-Length: 12275768");
header("Accept-Ranges: bytes");
header('Content-Disposition: attachment; filename="Untitled-1.bmp"');
header("Content-Transfer-Encoding: binary");
header("Connection: close");

//Send headers now

//because my php script take many time to finish
//because it downloads a file from a remote server

.
.
.

?>

Answer 1

I’m not sure how passthru works and if the command’s output is buffered somehow. But here’s another example using fopen, a streaming context for the request header fields and the chunked transfer coding with an explicit flush:

header("HTTP/1.1 200 OK");
header("Date: Thu, 23 Jun 2011 10:16:31 GMT");
header("Content-Type: application/octet-stream");
header("Accept-Ranges: bytes");
header('Content-Disposition: attachment; filename="Untitled-1.bmp"');
header('Content-Transfer-Encoding: chunked');
header("Connection: close");

$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en\r\n" .
              "Cookie: foo=bar\r\n"
  )
);
$context = stream_context_create($opts);
$fp = fopen('http://www.example.com', 'r', false, $context);
while (($buffer = fread($fp, 512)) !== false) {
    echo sprintf("%X", strlen($buffer)), "\r\n", $buffer, "\r\n";
    flush();
}
echo "0\r\n\r\n";
flush();

Make sure not to use ob_start or any other output buffering.