Note: For any non-trivial object schema you'll have to add annotations to support database specific functionality - such as relationships and indices. Annotating your Java Classes for Jalapeño works like the way it works for Hibernate. InterSystems is releasing NetBeans, Eclipse, and IntelliJ plug-ins for Caché 2007 that makes the process of adding annotations a point-and-click operation. Thus you can quickly define or modify the Object Storage in the Caché database.

An example of how a relationship is defined:

   // In the Department class
   @Relationship(type=RelationshipType.ONE_TO_MANY,inverseClass="Person")
   public ArrayList<Person> getEmployees(); // Method to return all employees

   // In the Person class
   @Relationship(type=RelationshipType.MANY_TO_ONE,inverseClass="Department")
   public Department getDepartment(); // Method to return the department

Ease of Persisting Objects
Once you have your databases created and configured, persisting your objects with any of these methods is very simple. Any of these is a distinct improvement over using JDBC/SQL and DAOs.

Hibernate
Once your Hibernate mappings are configured, persisting an object is very straightforward:

try{
SessionFactory factory = new Configuration().configure().buildSessionFactory();
Session session = factory.openSession();
Transaction tx = session.beginTransaction(); //optional
Person person = new Person("James","Hogan");
Long personID = (Long) session.save(person);
tx.commit();
session.close(); //optional
}catch(Exception e) {

}

DB4O
Once again, DB4O makes it extremely easy to persist your objects. Simply instantiate an object and then call db.set() on it.

ObjectContainer db=Db4o.openFile("C:\db4o\test.yapp");
try {
     Person person = new Person("James","Hogan");
     db.set(person); // It's now saved!
// commit is called implicitly when you close the container,
// so you don't really need to call it here.
db.commit(); //optional
}finally {
db.close();
}

Caché
Caché also makes it extremely simple to save your objects.

try {
/* Connect to this machine, in the SAMPLES namespace */
ObjectManager objectManager = connect (connectiontype, host, username,
password);
     Person person = new Person("James","Hogan");
        Object id = objectManager.save (person, false);
        objectManager.close ();
} catch (Exception ex) {

}

Ease of Retrieving Objects
Storing data is only half the equation. It must be easy to access your objects as well. Once again all three solutions simplify the process of getting an object.

Hibernate
You can use HQL or SQL to retrieve objects using Hibernate. For example:

package hello;
import java.util.*;
import org.hibernate.*;
import persistence.*;
public class HibernateExample {
public static void main(String[] args) {

Session session = HibernateUtil.getSessionFactory().openSession();
Transaction newTransaction = session.beginTransaction();
List people = newSession.createQuery("from Person m order by?m.name asc").list();
System.out.println( people.size() + " people found:" );

for ( Iterator iter = people.iterator();
iter.hasNext(); ) {
Person person = (Person) iter.next();
System.out.println( person.getName() );
}
newTransaction.commit();
newSession.close();
// Shutting down the application
HibernateUtil.shutdown();
}
}