Showcases high-concurrency state management and request throttling using thread-safe global storage. This example demonstrates the 'IncrementGlobalVar' atomic operation, illustrating how to implement sophisticated IP-based rate limiting with automatic temporal expiration (TTL), essential for protecting public API endpoints from denial-of-service and brute-force attacks in a distributed web environment.
var remoteIP := WebRequest.RemoteIP;
if remoteIP = '' then remoteIP := '127.0.0.1'; // Fallback for testing
// Define the rate limit key
var rateKey := 'RateLimit.Demo.' + remoteIP;
// Increment the counter. The expiration (10.0 seconds) means that
// if the user stops making requests for 10 seconds, the counter is deleted.
var requestCount := IncrementGlobalVar(rateKey, 1, 10.0);
PrintLn('<h3>Rate Limiter Demo</h3>');
PrintLn('<p>IP Address: ' + remoteIP + '</p>');
PrintLn('<p>Request count in the last 10 seconds: <strong>' + IntToStr(requestCount) + '</strong></p>');
if requestCount > 5 then begin
PrintLn('<div class="alert alert-danger">');
PrintLn(' <strong>Limit Exceeded!</strong> You have made more than 5 requests in 10 seconds.');
PrintLn(' Please wait 10 seconds before trying again.');
PrintLn('</div>');
end else begin
PrintLn('<div class="alert alert-success">');
PrintLn(' <strong>Access Granted.</strong> You are within the allowed limit (5 requests per 10s).');
PrintLn(' Refresh this page rapidly to trigger the rate limit.');
PrintLn('</div>');
end;
PrintLn('<hr>');
PrintLn('<p><small>The rate limit is tracked using a thread-safe global variable that expires automatically.</small></p>');
<h3>Rate Limiter Demo</h3> <p>IP Address: ::1</p> <p>Request count in the last 10 seconds: <strong>1</strong></p> <div class="alert alert-success"> <strong>Access Granted.</strong> You are within the allowed limit (5 requests per 10s). Refresh this page rapidly to trigger the rate limit. </div> <hr> <p><small>The rate limit is tracked using a thread-safe global variable that expires automatically.</small></p>