We have already seen in our previous section all the events that are announced by WireBox, but how do we listen? There are two ways to build WireBox listeners because there are two modes of operations, but the core is the same.

1. Listeners are simple CFCs that must create methods that match the same name of the event they want to listen to.

2. If you are running WireBox within a ColdBox application, listeners are Interceptors and you declare them and register them exactly the same way that you do with normal interceptors.

These methods can take up to two parameters depending on your mode of operation (standalone or ColdBox). The one main difference between pure Wirebox listeners and ColdBox interceptors are that the configure method for the standalone WireBox is different.

WireBox also sports a very nice event model that can announce several object life cycle events. You can listen to these events and interact with WireBox at runtime very easily, whether you are in standalone mode or within a ColdBox application.

Note If you are within a ColdBox application, you get the benefit of all the potential of ColdBox Interceptors and if you are in standalone mode, well, you just get the listener and that's it.

Each event execution also comes with a structure of name-value pairs called interceptData that can contain objects, variables and all kinds of data that can be useful for listeners to use. This data is sent by the event caller and each event caller decides what this data sent is. Also, remember that WireBox also can be ran with a reference to CacheBox, which also offers lots of internal events that you can tap into. So let's start investigating first the object life cycle events.

WireBox's offers a wide gamut of life cycle events that are announced at certain points in execution time. Below are the current events announced by the Injector wirebox.system.ioc.Injector.

Please note the configure() method in the standalone listener. This is necessary when you are using Wirebox listeners outside of a ColdBox application. The configure() method receives two parameters:

• injector : An instance reference to the calling Injector where this listener will be registered with.

• properties : A structure of properties that passes through from the configuration file.

As you can see from the examples above, each Listener component can listen to multiple events. Now you might be asking yourself, in what order are these listeners executed in? Well, they are executed in the order they are declared in either the ColdBox configuration file as interceptors or the WireBox configuration file as listeners.

Caution Order is EXTREMELY important for interceptors/listeners. So please make sure you order them in the declaration file.

So let's say that we want to listen on the beforeInjectorShutdown and on the afterInstanceCreation event in our listener.