using Astralis;
using Invercargill;
using Invercargill.DataStructures;
/// ClockEndpoint is a singleton SSE endpoint that broadcasts the current time
/// to all connected clients every second.
///
/// It demonstrates:
/// - Singleton pattern for SSE endpoints (shared state across connections)
/// - Implementing retry_interval property
/// - Using new_connection for initial welcome message
/// - Public method to broadcast events
public class ClockEndpoint : SseEndpoint {
private int connection_counter = 0;
private Mutex counter_mutex = Mutex();
/// Retry interval: clients should wait 3 seconds before reconnecting
public override uint retry_interval { get { return 3000; } }
/// Called when a new client connects - send welcome message
public override async void new_connection(SseStream stream) {
// Assign a unique connection ID
int connection_id;
counter_mutex.lock();
connection_id = ++connection_counter;
counter_mutex.unlock();
print(@"SSE client connected (connection #$connection_id, total: $(get_open_streams().length))\n");
// Send welcome message
try {
yield stream.send_event(new SseEvent.with_type("connected", @"You are connection #$connection_id"));
} catch (Error e) {
print(@"Failed to send welcome: $(e.message)\n");
}
// Listen for disconnection
stream.disconnected.connect(() => {
print(@"SSE client disconnected (connection #$connection_id)\n");
});
}
/// Public method to broadcast the current time to all connected clients.
/// This can be called from anywhere (e.g., from another endpoint or service).
public async void broadcast_time() {
var now = new DateTime.now_local();
var time_str = now.format("%H:%M:%S");
var date_str = now.format("%Y-%m-%d");
// Create event with current time
var time_event = new SseEvent.with_type("time", time_str);
// Also send a JSON-formatted message
var json_data = @"{\"time\":\"$time_str\",\"date\":\"$date_str\"}";
var json_event = new SseEvent.with_type("datetime", json_data);
// Broadcast to all connected clients
yield broadcast_event(time_event);
yield broadcast_event(json_event);
}
/// Start the broadcast loop. Called externally after construction.
public void start_broadcast_loop() {
broadcast_loop_iteration.begin();
}
private async void broadcast_loop_iteration() {
// Broadcast current time
yield broadcast_time();
// Schedule next iteration in 1 second
Timeout.add(1000, () => {
broadcast_loop_iteration.begin();
return false; // Don't repeat, we'll reschedule manually
});
}
}
/// IndexEndpoint serves a simple HTML page that connects to the SSE endpoints
class IndexEndpoint : Object, Endpoint {
public async HttpResult handle_request(HttpContext http_context, RouteContext route_context) throws Error {
var html = """
Astralis SSE Example
Astralis SSE Example
Live Clock (Broadcast)
Disconnected
--:--:--
""";
return new HttpStringResult(html)
.set_header("Content-Type", "text/html");
}
}
void main() {
var application = new WebApplication(8080);
// Register SSE endpoint as a singleton with an explicit factory
// This ensures the constructor logic runs
application.add_singleton_endpoint(
new EndpointRoute("/clock-stream"),
() => {
var endpoint = new ClockEndpoint();
endpoint.start_broadcast_loop();
return endpoint;
}
);
// Register the index page
application.add_endpoint(new EndpointRoute("/"));
print("SSE Example server running on http://localhost:8080\n");
print("Open http://localhost:8080 in your browser to see SSE in action\n");
application.run();
}