Server Sent Event (SSE)¶
Server-Sent Events, or SSE, is a web technology that allows a server to push real-time updates to a client, often the web browser), over a single HTTP connection. Unlike WebSockets, which are bidirectional, SSE is unidirectional: the server sends data to the client, but the client cannot send data back to the server over the same connection.
<?php
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
header('Connection: keep-alive');
// Send updates
while (true) {
$data = getLiveData(); // Fetch or generate data
echo "data: {$data}\n\n";
flush(); // Send output to the client immediately
sleep(1); // Wait before sending the next update
}
?>
See also Simple SSE in PHP and Server-Sent events with PHP and Symfony.
