There is a lot of info on this site about how to handle errors returned asynchronously from the Apple Push Notification Service in PHP. I came up with a method in PHP that seems to work pretty well, but I'd like some feedback.
- Is the use of fflush() correct? I've seen it in some examples but not all.
- I can't get it to give an error for a purposely bad device token. Why?
- Is this solution scalable to thousands of devices (assume PHP max memory is increased sufficiently)?
- Other issues?
Notes:
- Device tokens for the notification are stored in an array at the start.
- It's not asynchronous but it checks for (past) errors after sending each notification and checks one more time a full second after the last notification.
- It uses the newer "modern" notification format as opposed to the original or extended formats.
- It sends the index of the token array as the identifier to APNS.
- It uses a checkAppleErrorResponse() function which reads the first 6 bytes and returns either false or the identifier (index) that failed so it can back up and continue with the next token. (All tokens sent after a failure are invalidated.)
$ctx = stream_context_create();
stream_context_set_option($ctx, 'ssl', 'passphrase', $iosCertPassphrase);
stream_context_set_option($ctx, "ssl", "local_cert", $iosCertKey);
$fp = NULL;
$errno = NULL;
$errstr = NULL;
// same payload for all
$item2 = chr(2) . pack("n", strlen($payload)) . $payload; // payload item has id 2, a 2-byte length ("n") containing length of payload, then payload
$errorID = -1;
while ($errorID !== false) {
$fp = stream_socket_client($iosHost . ':' . $iosPort, $errno, $errstr, 60, STREAM_CLIENT_CONNECT|STREAM_CLIENT_PERSISTENT, $ctx);
if ($fp === FALSE) {
echo('Failed to create socket');
break;
}
stream_set_blocking($fp, 0);
for ($id = $errorID + 1 ; $id < sizeof($iosTokens); $id++) {
$errorID = false;
$item1 = chr(1) . pack('n', 32) . pack("H*", $iosTokens[$id]['device_token']); // device token item has 1-byte id 1, 2-byte length ("n") containing 32, then 32-byte device token
$item3 = chr(3) . pack('n', 4) . pack('N', $id); // notification identifier has 1-byte id 3, 2-byte length ("n") containing 4, then 4-byte identifier
$frame = $item1 . $item2 . $item3;
$msg = chr(2) . pack("N", strlen($frame)) . $frame; // for "modern" push notification format, msg has 1-byte id 2, 4-byte length ("N") containing the length of the frame, then frame
fwrite($fp, $msg);
$errorID = checkAppleErrorResponse($fp);
fflush($fp);
if ($errorID !== false) // if there's an error, stop now
break;
}
// if done with for loop and no errors, pause for a sec and check one last time
if ($errorID === false) {
$read = array($fp);
$null = null;
$changedStreams = stream_select($read, $null, $null, 0, 1000000);
//check if it is actually false
if ($changedStreams === false)
{
//close stream when done.
socket_close($fp);
fclose($fp);
}
elseif ($changedStreams > 0)
{
// set the error and redo starting after errorID index
$errorID = checkAppleErrorResponse($fp);
}
}
}
}
