You can disable copying of parameters by specifying -localnocopy flag on the rmi2iiop compiler. You can skip generation of local stubs all together by using the -nolocal flag.

The _servant_preinvoke and _servant_postinvoke give the ORB the opportunity to enfore the POA semantics of POA Manager, adapter activation, object activation etc.

// Wed Nov 19 16:39:05 EST 2003
                                                                           
package helloWorld2;
                                                                           
                                                                           
public class _Hello_Stub extends javax.rmi.CORBA.Stub 
    implements helloWorld2.Hello
{
    private static final String[] __ids = {
    |   "RMI:helloWorld2.Hello:0000000000000000"
    };
                                                                           
    public String[] _ids() { return __ids; }
                                                                           
    public java.lang.String sayHello() 
        throws java.rmi.RemoteException
    {
    |   _local_stub:
    |                                                                      
    |   if (javax.rmi.CORBA.Util.isLocal(this)) {
    |   |                                                                  
    |   |   // get the Servant Object
    |   |   org.omg.CORBA.portable.ServantObject _servObj =
    |   |       _servant_preinvoke("sayHello", helloWorld2.Hello.class);
    |   |   if (_servObj == null) break _local_stub;
    |   |                                                                  
    |   |   try {
    |   |   |   // invoke on the servant
    |   |   |   return ((helloWorld2.Hello) _servObj.servant).sayHello();
    |   |   |                                                              
    |   |   } catch (Throwable ex) {
    |   |   |   // copy the exception
    |   |   |   ex = (Throwable) javax.rmi.CORBA.Util.copyObject(ex, _orb());
    |   |   |                                                              
    |   |   |   throw javax.rmi.CORBA.Util.wrapException(ex);
    |   |   |                                                              
    |   |   } finally {
    |   |   |   _servant_postinvoke(_servObj);
    |   |   }
    |   }
    |                                                                      
    |   org.omg.CORBA_2_3.portable.InputStream in = null;
    |                                                                      
    |   try {
    |   |   try {
    |   |   |   // create an output stream
    |   |   |   org.omg.CORBA_2_3.portable.OutputStream out = 
    |   |   |       (org.omg.CORBA_2_3.portable.OutputStream) 
    |   |   |        _request("sayHello", true);
    |   |   |                                                              
    |   |   |   // do the invocation
    |   |   |   in = (org.omg.CORBA_2_3.portable.InputStream) _invoke(out);
    |   |   |   return (java.lang.String) in.read_value(java.lang.String.class);
    |   |   |                                                              
    |   |   } catch (org.omg.CORBA.portable.ApplicationException ex) {
    |   |   |                                                              
    |   |   |   // get the input stream
    |   |   |   in = (org.omg.CORBA_2_3.portable.InputStream)
    |   |   |       ex.getInputStream();
    |   |   |                                                              
    |   |   |   // read the exception id
    |   |   |   String id = ex.getId();
    |   |   |   in.read_string();
    |   |   |                                                              
    |   |   |   // unexpected exception
    |   |   |   throw new java.rmi.UnexpectedException(id);
    |   |   |                                                              
    |   |   } catch (org.omg.CORBA.portable.RemarshalException rex) {
    |   |   |   return sayHello();
    |   |   |                                                              
    |   |   } finally {
    |   |   |   _releaseReply(in);
    |   |   }
    |   |                                                                  
    |   } catch (org.omg.CORBA.SystemException ex) {
    |   |   throw javax.rmi.CORBA.Util.mapSystemException(ex);
    |   }
    }
                                                                           
}

// Wed Nov 19 16:39:05 EST 2003
                                                                           
package helloWorld2;
                                                                           
                                                                           
public abstract class HelloPOA
    extends org.omg.PortableServer.Servant
    implements org.omg.CORBA.portable.InvokeHandler, helloWorld2.Hello
{
    public org.omg.CORBA.ORB orb()
    {
    |   return _orb();
    }
                                                                           
    public void orb(org.omg.CORBA.ORB orb)
    {
    |   ((com.sssw.jbroker.POA.ServantDelegate)_get_delegate()).orb(this, orb);
    }
                                                                           
    public org.omg.CORBA.portable.OutputStream _invoke(String method,
        org.omg.CORBA.portable.InputStream in1,
        org.omg.CORBA.portable.ResponseHandler rh)
    {
    |   org.omg.CORBA_2_3.portable.InputStream in =
    |       (org.omg.CORBA_2_3.portable.InputStream) in1;
    |   org.omg.CORBA_2_3.portable.OutputStream out = null;
    |                                                                      
    |   try {
    |   |   if (method.equals("sayHello")) {
    |   |   |   java.lang.String result = sayHello();
    |   |   |   out = (org.omg.CORBA_2_3.portable.OutputStream)
    |   |   |       rh.createReply();
    |   |   |   out.write_value(result, java.lang.String.class);
    |   |   }
    |   |                                                                  
    |   |   else throw new org.omg.CORBA.BAD_OPERATION(method);
    |   |                                                                  
    |   } catch (org.omg.CORBA.SystemException ex) {
    |   |   throw ex;
    |   |                                                                  
    |   } catch (java.lang.Throwable ex) {
    |   |   throw new org.omg.CORBA.portable.UnknownException(ex);
    |   }
    |                                                                      
    |   return out;
    }
                                                                           
    private static final String[] __ids = {
    |   "RMI:helloWorld2.Hello:0000000000000000"
    };
                                                                           
    public String[] _all_interfaces(org.omg.PortableServer.POA poa, byte[] oid)
    {
    |   return __ids;
    }
                                                                           
}

// Wed Nov 19 16:39:05 EST 2003
                                                                           
package helloWorld2;
                                                                           
                                                                           
public class HelloPOATie
    extends helloWorld2.HelloPOA
    implements javax.rmi.CORBA.Tie, helloWorld2.Hello
{
    public HelloPOATie() {}
                                                                           
    public HelloPOATie(java.rmi.Remote target)
    {
    |   setTarget(target);
    }
                                                                           
    public org.omg.CORBA.Object thisObject() 
    {
    |   return _this_object();
    }
                                                                           
    public synchronized void deactivate() {}
                                                                           
    private helloWorld2.Hello _target;
                                                                           
    public void setTarget(java.rmi.Remote target)
    {
    |   _target = (helloWorld2.Hello) target;
    }
                                                                           
    public java.rmi.Remote getTarget()
    {
    |   return _target;
    }
                                                                           
    public java.lang.String sayHello() throws java.rmi.RemoteException
    {
    |   // delegate the invocation to target
    |   return _target.sayHello();
    |                                                                      
    }
}