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Meadow Application Lifecycle Events

Meadow provides several connection points to respond to important events in the process of launching and running your application, such as initialization, errors, and sleep states.

These events are channeled through methods on the App base class and events on the platform OS available through the current Meadow device being used.

Platform OS lifecycle events​

The sleep and resume events are handled by the platform operating system where your Meadow code is executing. These are standard .NET events where you can attach a handler either inline or via a delegate.

BeforeSleep​

  • Device.PlatformOS.BeforeSleep += () => {...};

The BeforeSleep event is called prior to your application sleeping via the Device.PlatformOS.Sleep(...) method, allowing you a chance to resolve anything before the Meadow device enters a power-saving sleeping mode.

Device.PlatformOS.BeforeSleep += () =>
{
    Resolver.Log.Info("Device is about to enter sleep mode");
    // Actual serial output is asynchronous, so we need to delay a little to ensure the output is completed before Meadow sleeps.
    Thread.Sleep(500);
};

AfterWake​

  • Device.PlatformOS.AfterWake += () => {...};

The AfterWake event is called when your application resumes execution after sleeping via the Device.PlatformOS.Sleep(...) method, allowing you a chance to restore anything before the Meadow device starts executing your code again.

Device.PlatformOS.AfterWake += () =>
{
    Resolver.Log.Info("Device has returned from sleep mode");
};

BeforeReset​

  • Device.PlatformOS.BeforeReset += () => {...}

The BeforeReset event is called prior to your application sleeping via the Device.PlatformOS.Reset() method, allowing you a chance to resolve anything before the Meadow device restarts completely.

Device.PlatformOS.BeforeReset += () =>
{
    Resolver.Log.Info("Device is about to reset");
    // Actual serial output is asynchronous, so we need to delay a little to ensure the output is completed before Meadow restarts.
    Thread.Sleep(500);
};

Application event lifecycle methods​

Your application can respond to application lifecycle events through methods on the App base class. You can overload these App methods to have your own code executed when these lifecycle events occur.

For the App methods, the default implementations are often empty, but if your app is inheriting from a parent class that has its own app lifecycle event implementations, you may want to call those parent event handlers from your own app overrides.

Initialize​

  • Task Initialize()

The Initialize method is called once when Meadow is first booted. It is also called once when Meadow is restarted either via reset or automatic error recovery.

Run​

  • Task Run()

The Run method is called once after your app's Initialize method.

OnReset​

  • void OnReset()

The OnReset method is called after Meadow restarts, either manually via Device.PlatformOS.Reset() or via automatic error recovery.

OnShutdown​

  • Task OnShutdown()

The OnShutdown method is called before the Meadow is shut down, offering an opportunity to perform some clean-up before stopping execution of your app.

OnError​

  • void OnError(Exception e)

The OnError method is called when your application causes an unhandled exception, but before it stops running your app or triggers any automatic error recovery. You will have a chance to inspect and, optionally, handle this error.