[jboss-user] [JBoss Seam] - @Unwrap question

[enzhao]

Hi folks,

I would like to use the @Unwrap annotation in an APPLICATION scoped dataStore bean. This stateless bean mainly caches the read-only static data which would be used in the application. I'd like to learn more detail about the @Unwrap than which are already presented in the reference manual. (I build a new Seam dist everyday from the CVS, so my reference manual is always the latest.)

Here are my questions:

1. What's the difference between @Factory and @Unwrap in the following two code fragments? (from reference section 3.8)

  | @Factory(scope=CONVERSATION)
  | public List<Customer> getCustomerList() { 
  |     return ... ;
  | }
  | 

and 

  | @Name("customerList")
  | @Scope(CONVERSATION)
  | public class CustomerListManager
  | {
  |     ...
  |     
  |     @Unwrap
  |     public List<Customer> getCustomerList() { 
  |         return ... ;
  |     }
  | }
  | 

The reference says 
anonymous wrote : 
  | A manager component is any component with an @Unwrap method. This method returns the value that will be visable to clients, and is called every time a context variable is referenced.
  | 
Doesn't the method in first code fragment with the @Factory annotation also return a List? Is it not visible to clients?

2. The reference says:
anonymous wrote : 
  | An even more powerful pattern is the manager component pattern. In this case, we have a Seam component that is bound to a context variable, that manages the value of the context variable, while remaining invisible to clients.
  | 

What does the manager component here exactly manage? And in which situation/context is this manager component pattern bestly used? I looked at the HenHouse example, it seems useful when dealing with events which would cause value changes in the managed list.

Many thanks in advance for any enlightenment!



Regards,
Ellen 

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