What are the advantages and disadvantages of using Longpolling/Comet technique in PHP for monitoring variable changes?

Issue: Monitoring variable changes in real-time can be achieved using Longpolling/Comet technique in PHP. This involves the server holding the request open until there is new data to send back to the client, allowing for real-time updates without the need for constant polling. 

<?php
// Longpolling/Comet technique for monitoring variable changes in PHP

// Set the content type to text/event-stream
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');

// Long-polling loop
while(true) {
    // Check for variable changes
    if($variable_has_changed) {
        // Send the updated variable value to the client
        echo "data: $variable_value\n\n";
        // Flush the output buffer
        ob_flush();
        flush();
        // Exit the loop after sending the update
        break;
    }
    // Delay before checking again
    sleep(1);
}
?>

Keywords

Longpolling Comet technique PHP monitoring variable changes

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