Doubt on interfaces for EJB 3

[Joe Harry]

Guys,

The following is from EJB 3 in Action,

public interface BidManager{
void addBid(Bid bid);
List<Bid> getBids(Item item);
}
@Local
public interface BidManagerLocal extends BidManager {
void cancelBid(Bid bid);
}
@Remote
public interface BidManagerRemote extends BidManagerLocal {
}
@WebService
public interface BidManagerWS extends BidManager {
}

If you want, you can apply the @Local, @Remote, or @WebService annotation in the
bean class without having to implement the business interface as follows:

@Remote(BidManager.class)
@Stateless
public class BidManagerBean {
...
}

My question here is with the @Remote annotation specified in the code above as it says that BidManager.class which is a POJI is the Remote interface for this session bean. So does this imply that when I write my client class (which is going to be a remote client), can I do a DI like this below,

public class ClientClass {
...
...
@EJB
static BidManager bidManager; //Will this act as my remote reference? 
Will my container figure out that it is actually a subclass of BidManager
which is BidManagerRemote and do look up for the corect Remote reference?
...
...
}

OR do I have to do this,

public class ClientClass {
...
...
@EJB
static BidManagerRemote bidManager;
...
...
}

Please help guys!
[ September 03, 2008: Message edited by: Jothi Shankar Kumar Sankararaj ]

[Sergio Tridente]

Hi Jothi,

In the following code:

@Remote(BidManager.class)
@Stateless
public class BidManagerBean {
...
}

The BidManagerBean business remote interface is BidManager. There are no other business interfaces. So the proper way to get a reference to your bean will be to define:

public class ClientClass {
...
...
@EJB
static BidManager bidManager;
...
...
}

You cannot use

public class ClientClass {
...
...
@EJB
static BidManagerRemote bidManager;
...
...
}

BidManagerRemote is NOT a business interface of BidManagerBean.

[Sergio Tridente]

Here's another scenario:

You define the following:

@Stateless
public class BidManagerBean implements BidManagerRemote {
...
}

Now you have the obvious choice of doing DI as follows:

public class ClientClass {
...
...
@EJB
static BidManagerRemote bidManager;
...
...
}

And the not so obvious:

public class ClientClass {
...
...
@EJB(beanInterface=BidManagerRemote.class)
static BidManager bidManager;
...
...
}

The beauty of EJBs ;-)

[Joe Harry]

Originally posted by Sergio Tridente:
Hi Jothi,

In the following code:

@Remote(BidManager.class)
@Stateless
public class BidManagerBean {
...
}

The BidManagerBean business remote interface is BidManager. There are no other business interfaces. So the proper way to get a reference to your bean will be to define:

public class ClientClass {
...
...
@EJB
static BidManager bidManager;
...
...
}

You cannot use

public class ClientClass {
...
...
@EJB
static BidManagerRemote bidManager;
...
...
}

BidManagerRemote is NOT a business interface of BidManagerBean.

I competely got what you are trying to convey. Thanks for the response! Another question here is, can I also say the same interface to be a Local interface?

@Remote(BidManager.class)
@Local(BidManager.class)
@Stateless
public class BidManagerBean {
...
}

Would this be right?

[Sergio Tridente]

Accordingly to section 4.6.6 of the ejb core specification:

The same business interface cannot be both a local and a remote business interface of the bean.

[Joe Harry]

Thanks Sergio!