Bits of .NET

public class StartupService : IHostedService
{
    public async Task StartAsync(CancellationToken cancellationToken)
    {
        // Runs when app starts
        await WarmCacheAsync();
        await CheckDatabaseConnectionAsync();
    }

    public async Task StopAsync(CancellationToken cancellationToken)
    {
        // Runs when app stops (graceful shutdown)
        await FlushLogsAsync();
        await CloseConnectionsAsync();
    }
}

// Register
services.AddHostedService();

Use Cases: Cache warming, health checks, cleanup tasks, connection pooling.

Execution Order: StartAsync runs before app accepts requests. StopAsync during graceful shutdown.