Built-in Events

Lifecycle and diagnostic events fired by the Pixie System

Pixie fires several built-in events during the lifecycle of the System. All event classes are in the org.tomitribe.pixie.event package.

Lifecycle Events

Event	Fired When
`PixieLoad`	After `system.load(properties)` completes. Contains the loaded `Properties`.
`PixieClose`	When `system.close()` is called.

public class StartupListener {
    public void onLoad(@Observes final PixieLoad event) {
        log.info("System loaded with " + event.getProperties().size() + " properties");
    }

    public void onClose(@Observes final PixieClose event) {
        log.info("System shutting down");
    }
}

System implements Closeable, so it works with try-with-resources:

try (final System system = new System(properties)) {
    // PixieLoad fires after construction
    // ...
}   // PixieClose fires here

Component Events

Event	Fired When
`ComponentAdded<T>`	A component is added to the System. Contains the type and instance.
`ComponentRemoved<T>`	A component is removed from the System. Contains the type and instance.

public class ComponentTracker {
    public void onAdded(@Observes final ComponentAdded<?> event) {
        log.info("Added: " + event.getType().getSimpleName());
    }
}

Observer Events

Event	Fired When
`ObserverAdded`	An observer is registered with the System. Contains the observer instance.
`ObserverRemoved`	An observer is unregistered. Contains the observer instance.

Dispatch Events

Event	Fired When
`BeforeEvent<T>`	Before an event of type `T` is dispatched. See Before & After.
`AfterEvent<T>`	After an event of type `T` has been dispatched. See Before & After.

Error Events

Event	Fired When
`ObserverFailed`	An observer method threw an exception. Contains the observer, method, original event, and throwable.
`ObserverNotFound`	No observers exist for a fired event. Contains the original event.

public class ErrorHandler {
    public void onFailure(@Observes final ObserverFailed event) {
        log.error("Observer " + event.getMethod().getName() + " failed: "
                + event.getThrowable().getMessage());
    }

    public void onMissing(@Observes final ObserverNotFound event) {
        log.warn("No observers for: " + event.getEvent().getClass().getSimpleName());
    }
}

Observer exceptions are caught by Pixie — they do not propagate to the event producer and do not prevent other observers from being called.