Can't cast home stub to home interface

Question

WL 5.1
          NT4.0
          I'm trying to talk to an EJB from a servlet. I had been doing this successfully
          using tomcat for the servlet engine and WL as the app server. Now, I wish
          to get this working using WL's servlet engine and WL app server.
          I look up the home like this:
          (this class is in a base class)
          protected Object lookupHome( String jndiName, Class serviceClass ) throws NamingException
          InitialContext initialContext = new InitialContext();
          return javax.rmi.PortableRemoteObject.narrow( initialContext.lookup( jndiName ),
          serviceClass );
          (this class is a derived class)
          private FooHome getHome() throws NamingException
          return (FooHome)lookupHome( "Foo", Foo.class ); // !!!!!!!!!!!!<-----this cast fails
          The cast to (FooHome) fails, with a ClassCastException. I've looked at what is returned from the
          initialContext and after narrowing and the object is what it should be: FooHomeBeanImpl_ServiceStub.
          At anyrate, I compared what I get back using tomcat and what I get back using WL's servlet engine
          and
          they are the same.
          So the above works using tomcat/WL but fails for WL/WL.
          The obvious difference is that the tomcat -> WL involved to JVMs, one
          for tomcat, one for WL. I believe with WL-> WL there is only one JVM.
          I'm a bit baffled. Any clues would be very much appreciated.
          Thanks.
          

Answer 1

Yes, you will see many older messages in this forum related to this issue.
          The home and remote interfaces and any other classes "mentioned" therein are
          "exported" by the ejb jar class loader to the rest of the classes running on
          that instance of web logic.
          Cameron Purdy
          [email protected]
          http://www.tangosol.com
          WebLogic Consulting Available
          "Rich Johns" <[email protected]> wrote in message
          news:[email protected]...
          > Sorry to reply to my own, but I thought I'd report that I've fixed the
          > problem which was related to loading the same class from multiple jars.
          >
          > Apparently, (and admittedly I'm still a bit shaky on this) servlets can
          > see interfaces for already deployed EJBs loaded via the deployment jar.
          This means that you should
          > not load them for the benefit of the servlet on the servlet classpath. For
          example,
          > the servlet might need home and/or remote bean interfaces, but, since they
          > are already deployed beans, you don't need to explicitly put them on the
          > weblogic.httpd.servlet.classpath. I believe the same goes for WARs
          (whether
          > they are zipped or unfolded).
          >
          > Just what subset of classes in the deployment jar can be seen by a
          servlet? The
          > reason I ask this is because there are some classes in the deployment jar
          that
          > my servlet cannot see. These classes are not used by the deployed beans,
          but
          > they are used by the servlet. I had to make a separate jar containing
          these files.
          > (Eventually, they will not be part of the deployment jar.)
          >
          > So, is this a correct inference? Only files that the EJB classloader
          loaded,
          > which which is to say the EJB interfaces, stubs, and other classes used
          > by them, are actually visible to the servlet.
          >
          >
          > Rich Johns wrote:
          >
          > > WL 5.1
          > > NT4.0
          > >
          > > I'm trying to talk to an EJB from a servlet. I had been doing this
          successfully
          > > using tomcat for the servlet engine and WL as the app server. Now, I
          wish
          > > to get this working using WL's servlet engine and WL app server.
          > >
          > > I look up the home like this:
          > >
          > > (this class is in a base class)
          > > protected Object lookupHome( String jndiName, Class serviceClass )
          throws NamingException
          > > {
          > > InitialContext initialContext = new InitialContext();
          > > return javax.rmi.PortableRemoteObject.narrow(
          initialContext.lookup( jndiName ),
          > > serviceClass );
          > > }
          > >
          > > (this class is a derived class)
          > > private FooHome getHome() throws NamingException
          > > {
          > > return (FooHome)lookupHome( "Foo", Foo.class ); //
          !!!!!!!!!!!!<-----this cast fails
          > > }
          > >
          > > The cast to (FooHome) fails, with a ClassCastException. I've looked at
          what is returned from the
          > > initialContext and after narrowing and the object is what it should be:
          FooHomeBeanImpl_ServiceStub.
          > >
          > > At anyrate, I compared what I get back using tomcat and what I get back
          using WL's servlet engine
          > > and
          > > they are the same.
          > >
          > > So the above works using tomcat/WL but fails for WL/WL.
          > >
          > > The obvious difference is that the tomcat -> WL involved to JVMs, one
          > > for tomcat, one for WL. I believe with WL-> WL there is only one JVM.
          > >
          > > I'm a bit baffled. Any clues would be very much appreciated.
          > >
          > > Thanks.
          >