So I'm having an issue getting Server Side Events working with PHP. I've tried various different tutorials online that utilise an infinite while loop but all of my attempts end up in a 500 error after a couple of minutes, instead of the data being sent.
For my application I need the script to keep running in an infinite loop as I'm getting updates from a hardware device via TCP sockets, and for the device to send me updates I have to keep the socket connection open.
My setup is as follows:
PHP Version 7.3.33
Windows Server 2022 with IIS 10 (Also tried on Windows Server 2016 with IIS 10)
output_buffering and zlib.output_compression are both set to "Off"
responseBufferLimit is set to 0 in the FastCGI Handler settings for PHP.
The basic test code I'm currently using is as follows:
sse.php
<?PHP
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
while(true) {
$now = date('r');
echo "data: The time is : {$now}\n\n";
@ob_flush();
flush();
sleep(2);
}
?>
test.html
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Untitled Document</title>
</head>
<body>
<script>
var source = new EventSource("sse.php");
source.onopen = function(e) {
console.log("The connection to your server has been opened");
}
source.onmessage = function(e) {
console.log ("message: " + e.data);
}
source.onerror = function(e) {
console.log("The server connection has been closed due to some errors");
}
</script>
</body>
</html>
This should (in theory) send a data string to the client with the current time every 2 seconds, but instead is 500 erroring. I must add it is only when a while loop is implemented. If I remove the while loop then it works with the client reconnecting every 3 seconds (which won't work for my application).
The PHP logs only show the following errors which don't appear to be linked to my issue, unless anyone can suggest otherwise:
[17-Nov-2022 21:26:28 UTC] PHP Warning: Module 'mysqli' already loaded in Unknown on line 0
[17-Nov-2022 21:26:28 UTC] PHP Warning: Module 'mbstring' already loaded in Unknown on line 0
[17-Nov-2022 21:26:28 UTC] PHP Deprecated: Directive 'track_errors' is deprecated in Unknown on line 0
I've searched for days for a solution with nothing working so far. Does anyone have any suggestions on potential settings that need altering with the IIS/PHP setup to get this to work?
Some tutorials have suggested making these config changes: php.ini > output_buffering and zlib.output_compression set to "Off" responseBufferLimit is set to 0 in the FastCGI Handler settings for PHP.
But neither of these have had any effect on the script.
