[cdi-dev] Event type

Marko Lukša marko.luksa at gmail.com
Wed Aug 29 10:21:29 EDT 2012

I have been reading the spec about events and I'm a little confused.

In "Chapter 10. Events", the spec says:

  * An event comprises: - A Java object—the/event object/
  * The event object acts as a payload
  * An observer method will be notified of an event if the *event object
    is assignable to the observed event type

I understand this to mean that the actual payload is what's important 
when resolving observer methods. Yet, this is not true when firing 
events through the Event bean. When firing events through the Event 
bean, observers are resolved according to the type parameter of the 
injected Event bean (or the type passed to event.select()) and not the 
actual type of payload supplied to event.fire(payload) (see 

In WELD, the actual type of the payload is only important when firing 
events through BeanManager.fireEvent(), which is not even mentioned in 
"10.3. Firing events". From 10.3, I would expect that the usual way of 
firing events is through the Event bean, and firing events through the 
BeanManager is the low-level way of doing it.

I have a few more questions, but they are all inter-dependent, so it's 
probably better if you help me resolve this one first, and then I'll 
move on to the rest.


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