Re: A design question...

[Christensen, Kurt]

You don't expect my hare-brained ideas to actually *work*, do you? :-)

If you want to try it out, the client would look something like this
(remember to insert proper exception handling code and blah blah blah):

public class CarClient
{
    // ...

    // Get CarProxy. See below...
    CarProxy carProxy = new CarProxy();
    Car car = carProxy.findByPrimaryKey(CarPK carPK);

    // At this point, "car" could be a reference to
    //   a Car, or a SportsCar, or any other subclass...

    // ...
}

...where we have something like this:

public class CarProxy
{
    private EJBHome _myEJBHome;
    private Method  _myFinderMethod;

    public CarProxy()
    {
        this( "CarHome" );
    }

    public CarProxy( String jndiHomeName )
    {
        // Get JNDI context (app-server specific code here)
        Context context = new InitialContext();

        // Get EJBHome object
        Object o = context.lookup( "CarHome" );

        // Perform CORBA narrowing voodoo
        _myEJBHome = (EJBHome)PortableRemoteObject.narrow( o, EJBHome.class
);

        // Get the metadata for this EJB (we need to do all this
        //   because EJBHome doesn't define findByPrimaryKey() )
        EJBMetaData ejbMetaData = ejbHome.getEJBMetaData();

        // Get the Home class for the EJB from the metadata
        Class ejbHomeClass = ejbMetaData.getHomeInterfaceClass();

        // Get the finder method
        Class[] argTypes = { CarPK.class };
        _myFinderMethod = ejbHomeClass.getMethod( "findByPrimaryKey",
argTypes );
    }

    public Car findByPrimaryKey( CarPK carPK )
    {
        Object[] args = { carPK };
        return _myFinderMethod.invoke( _myEJBHome, args );
    }
}

public class SportsCarProxy
{
    public SportsCarProxy()
    {
        super( "SportsCarHome" );
    }
}


Again, note that this all assumes that certain other inheritance
relationships are in place: SportsCarPK must extend CarPK, and SportsCarBean
should extend CarBean, and whatever else you may need.

KurtC


-----Original Message-----
From: Tom Lepski [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, August 08, 2000 1:16 AM
To: [EMAIL PROTECTED]
Subject: Re: A design question...


Hi Kurt,
Thanks for the pointer but I'm still clueless about the client side code.
Could you please tell me how would  a client can get all the cars (including
SportsCars) by calling just one findByXXX() method.

thanks for your help,
Tom.

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