question about application scope component?

[liudan2005]

I have an entity bean which maps to a database table. I need to retrive some data from database through this entity bean when applicaiton starts up so all other back beans and ejbs can access it. I am thinking of making an application scoped object, which retrives data when applicaton starts up. What's the best way to make the object ? If it's in a J2SE environment, I would make it a Pojo with all field static and retrive data through jdbc in static block. Now is seam environment, I think it should be a application scoped object. Should I make it a backbean, or stateless/stateful ejb. This object is gonna be frequently access by other component So I wanna know what would be the best way to achive the performance

[gavin.king]

Just make it an APPLICATION scoped Seam component. You can use the @Startup annotation to ensure it gets instantiated during the startup cycle. Retrieve the data in an @Create method.

[liudan2005]

Thanks for your help Gavin.
I followed you and made a seam component(not a stateful or stateless bean) with following annotations:
@Name("globalparams")
@Scope(ScopeType.APPLICATION)
@Startup
@Interceptors(SeamInterceptor.class)
this works fine but I can't inject @PersistenceContext EntityManager anymore, it seems I can only inject EntityManager in a stateful or stateless ejb. Since I need to retrive data in my @Create method, I need to inject an EntityManager or another ejb using @Ejb. I've tried both way but non of them work. Is there any better to do this?

[liudan2005]

Problem solved by use:
InitialContext ctx = new InitialContext();
ctx.lookup("app/beanname/local");

Thanks.

[gavin.king]

The other option is to use a seam-managed EntityManager.

@PersistenceContext only works in an EJB.

[jboss-nth-fan]

Hi Folks,

I have the exact same issue here, however not sure how to use the seam-Managed EM.

Just to be sure, is it the one in: "13.4.2. Using a Seam-managed persistence context" from the Seam Ref Doc 1.1.CR2 ?

I've tried (as per ref) to add it to the components.xml, no luck

<core:managed-persistence-context name="bookingDatabase" auto-create="true"
persistence-unit-jndi-name="java:/EntityManagerFactories/bookingData"/>

The DTD for components.xml does not seem to like the 'core' tag, or is the Documentation incorrect ?

Any pointers will be helpful !

Yeyo

[gavin.king]

You must use XSDs, not a DTD. Look at the booking example to see how.

[jboss-nth-fan]

Indeed, that's clear now.

Maybe I've got the DTD definition (and the error) as I was using a scaffolded Entity from SeamGen.

Thanks for your promptly assistance!

Yeyo

[jboss-nth-fan]

Ignore my last comment, I've just confirmed it's fixed in CVS in 1.5

Y