[weld-dev] [jsr-299-eg] Updated spec with @BeanTypes and clarification of @New

[Pete Muir]

On 20 Oct 2009, at 01:24, Roberto Chinnici wrote:

>>
>>
>> No it doesn't! Thats the whole point!
>>
>> Pete of course has implemented this without scanning of non-bean
>> deployment archives.
>>
>
> Scanning for @Resource at deployment time, not scanning for beans as  
> such.

Let's step through this, as there seems to be a lot of confusion here  
(particularly around new scanning requirements):

* Something which is allowed to perform injection (such as a Java EE  
component class or a managed bean *in a bean deployment archive*, so  
no *new* scanning here), has an injection point which has @New on it:

@Inject @New Foo foo

where Foo is a class which exists in a module or library which is not  
a bean deployment archive.

* When this injection point is registered with the 299 container, it  
sees that it doesn't know about Foo as a bean already, so it creates a  
new Bean object (e.g. of type NewManagedBean)

* In creating this Bean object, it scans the class for annotations on  
fields, methods, constructors and parameters (this I guess is extra  
scanning [1])

[1] Scanning a class like this has a very low overhead (at least in  
the Sun JDK) when compared to loading class definitions for scanning  
for class level annotations (such as @ManagedBean). I offered to do  
some profiling on this to back up my assertion, but never got asked to  
take it further. Further, an implementor is free to centralise their  
scanning and thus lower their overhead further.