On Mar 23, 2009, at 12:46 PM, Scott Hernandez wrote:

> And everything is fine, but if I add another Queue (in resin-web.xml)
> then I get a problem as I have more than one Queue and it is not
> unique for injection. Now, in the examples it shows using
> @Named("QueueName") but that annotation cannot be applied to a field
> as the example seems to indicate.
>       @Named("userUpdates")
>       private BlockingQueue userUpdateQueue;  
> How do I differentiate between the queues in my injection annotations?

The docs are a bit out of date, because the Java Injection spec has  
changed a bit from the earlier draft.  "@Named" is now _only_ for EL  
naming, not for binding.

In this case, you're supposed to create your own @BindingType  
annotation, @UserUpdates.  So you inject it like:

   private BlockingQueue userUpdateQueue;

And you configure it like:

    <mypkg:UserUpdates xmlns:mypkg="urn:java:com.me.mypkg"/>

(I'd put the xmlns:mypkg at the top in a real config file.)

Creating the annotation is a little bit of extra work but has the  
following advantages:

   1. it's "type safe", i.e. the compiler (and Java Injection) can  
verify the @UserUpdates is a valid @BindingType annotation, e.g.  
saving you from typos.
   2. it's documented by JavaDoc, so you can explain the purpose of  
the @UserUpdates
   3. it fits into IDEs, because IDEs have access to the annotation  
and to the xmlns of your configuration
   4. it gives you a chance to think carefully about the organization  
of your components, in this case to double check that "UserUpdates" is  
a logical and self-documenting description of the queue you're using.

The UserUpdates annotation is defined like:

   package com.me.mypkg;

   import static java.lang.annotation.ElementType.*;
   import static java.lang.annotation.RetentionPolicy.*;
   import java.lang.annotation.Retention;
   import java.lang.annotation.Target;

   import javax.inject.BindingType;

   public @interface UserUpdates {

(Resin does have a com.caucho.config.Name for generic things like  
databases, but that kind of general annotation is discouraged.)

-- Scott
> Thanks in advance,
> Scott
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