That's an interesting topic, if I might butt in :) The technique you
mentioned below works great in jBoss, but when I tried to port the same code
to another server running Darth WebLogic, it complained about some obscure
j2ee specification requiring the home and remote interfaces being *unique*
or having the same name as the EJB.
The technique you use below is very powerful, as it allows a layer of
abstraction. My question then is the technique below legal?
Wes
-----Original Message-----
From: David Ward [mailto:[EMAIL PROTECTED]]
Sent: Monday, July 02, 2001 10:18 AM
To: [EMAIL PROTECTED]
Subject: Re: [JBoss-user] Casting home interface to correct bean type
Chris,
You shouldn't have to cast your home interfaces; in fact, you can share
the same remote and home interface for all your "Form" EJB
implementations. Try this, for example:
// interfaces/beans
public interface Form extends EJBObject;
public interface FormHome extends EJBHome;
public class FooForm implements SessionBean;
public class BarForm implements SessionBean;
// inside servlet (bad code for ease of example)...
public void service(HttpRequest req, HttpResponse res) {
String formName = req.getParameter("formName");
try {
InitialContext ctx = new InitialContext();
Object ref;
if ( formName.equals("foo") )
ref = ctx.lookup("java:comp/env/ejb/FooForm");
else if ( formName.equals("bar") )
ref = ctx.lookup("java:comp/env/ejb/BarForm");
else
// do something...
FormHome home = (FormHome)PortableRemoteObject.narrow(ref,
FormHome.class);
Form form = home.create();
// now use the generic form interface...
} catch (Exception e) {
throw new ServletException(e);
}
}
Basically, your deployment descriptor will specifcy the same <remote>
and <home> interfaces for both FooForm and BarForm, but will obviously
have different <ejb-class>'s bound to different JNDI names. Your
implementations of FooForm and BarForm can be radically different, but
since you said they will have the same method signatures, the client
code can just use the "Form" interface.
Hope this helps,
David
--
Chris Adams wrote:
> Hi,
>
> Need some help with remote casting objects when using ejb's
>
> I'm going to have a set of bean which each represent a form. Each for has
> the same set of methods, but they need to be independent ejb's because
each
> has different details.
>
> The client is a servlet, which will receive a parameter
> the type of form to return. This then needs to get the home interface of
> the bean. I am going to have a properties file which pairs the form name
to
> it's home interface class name.
>
> My problem is that the lookup method just returns an object, so how can I
> cast this object to the correct home interface, as the type of form is not
> know until the servlet is called.
>
> I've tried creating standard interfaces, which all form beans could
inheret
> from, but came up with all sort of problems.
>
> I could use relfection to call the methods, but would prefer not to. Any
> ideas.
>
> Many Thanks
>
> Chris Adams
>
>
>
>
> Chris Adams
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--
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David Ward [EMAIL PROTECTED]
Senior Software Engineer http://www.dotech.com
Distributed Object Technologies, Inc. 716-381-8320 (phone)
500 Linden Oaks, Rochester, NY 14625 716-381-0598 (fax)
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