9.10 Container Events

Windsor container uses .NET events to notify external subscribers when something interesting happens. You can subscribe to these events and perform some logic as they occur.

:information_source: Use facilities: Primary usage of these events is for facilities. While there's no limitation for who can subscribe it is considered a good practice to encapsulate this logic within a facility.

The events

The events are defined on IKernelEvents interface that is exposed by container's Kernel property. The following events are provided.

Container events

Events regarding lifetime of the container.

AddedAsChildKernel

Raised when current container was added as child container of some other container.

RemovedAsChildKernel

Opposite of the above.

RegistrationCompleted

:information_source: This event is new in Windsor 3

Raised when registration / installation process is completed, that is right before the container exist Install or Register (whichever is the outermost).

ComponentModel events

Events regarding lifetime of a ComponentModel in the container.

ComponentRegistered

Raised when a new component gets registered with the container.

ComponentUnregistered

Raised when a component gets removed from the container.

ComponentModelCreated

Raised when a ComponentModel gets created, but after ComponentModel construction contributors finish their job.

:information_source: Don't modify the ComponentModel when handling this event: You should never perform any modification to the ComponentModel passed to this event. Use ComponentModel construction contributors for that.

:warning: Obsolete warning: It is best if you try not to use the events mentioned above. In future version they may become obsolete and eventually be removed from the API.

Handler events

Events regarding lifetime of a IHandler.

HandlerRegistered

Raised when a new handler is registered (it might be in a valid or waiting dependency state).

HandlersChanged

Raised when a new handler (or group of handlers) is registered (they might be in a valid or waiting dependency state). The difference from HandlerRegistered is the intent - while the former is concentrated on the newly registered handler, this one is simply a notification that state of the container has changed. Windsor, for example, uses it internally to check if newly registered handlers satisfy missing dependencies of other handlers in WaitingDependency state.

Component events

Events regarding lifetime of a component instance.

ComponentCreated

Raised right after component was created.

ComponentDestroyed

Raised right after component was destroyed.

DependencyResolving

Raised right after a dependency was resolved. This event is useful to perform some modification on resolved component, similar to OnCreate method, but globally.

EmptyCollectionResolving

:information_source: This event is new in Windsor 3

Raised when a collection is being resolved (via IKernel.ResolveAll method, or indirectly - via collection resolver) and the collection is empty. Implementors would usually log that fact or potentially throw an exception (especially in development).