Lazy handling of JAXB classes

Question

I have an application with 2500 possible java classes which can be returned by web services (done with CXF).
The problem is that creating a JAXB context for the 2500 classes takes a long time and lots of memory while on most scenarios only 200 classes will really be required. What I would want is a JAXB context which knows to do lazy handling only for the needed classes (delay all the code generation stuff to when the class is needed).
I know the current implementation doesn't support it but I would like to extend it.
If someone knows about possible hooks or a good starting point it will be great.
Another point is which engine will be easier yo extend, moxy or metro. Thanks in advance,
Avner

Answer 1

With EclipseLink JAXB (MOXy) you can use the SESSION_EVENT_LISTENER property to enable lazy initialization on the underlying metadata as follows:

import java.util.*;
import javax.xml.bind.JAXBContext;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.jaxb.JAXBContextProperties;
import org.eclipse.persistence.oxm.XMLDescriptor;
import org.eclipse.persistence.sessions.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>();
        properties.put(JAXBContextProperties.SESSION_EVENT_LISTENER, new SessionEventAdapter() {

            @Override
            public void preLogin(SessionEvent event) {
                for(Map.Entry<Class, ClassDescriptor> entry : event.getSession().getProject().getDescriptors().entrySet()) {
                    XMLDescriptor a;
                    ((XMLDescriptor) entry.getValue()).setLazilyInitialized(true);
                }
            }

        });
        JAXBContext jc = JAXBContext.newInstance(new Class[] {Root.class}, properties);
    }

}

The JAXB reference implementation has a similar property which I can't find at the moment. If no one posts that as an answer you can post a question to their mailing list:

• https://java.net/projects/jaxb/lists/