We saw in the JDO Tutorial the overall process for adding
persistence to a simple application. In that tutorial we persisted the objects to an
RDBMS. Here we show the differences when persisting instead to the
db4o object datastore.
Step 1 : Design your domain/model classes as you would do
Step 2 : Define their persistence definition using Meta-Data.
Step 3 : Compile your classes, and instrument them (using the
Step 4 : Generate the database tables where your classes are to
Step 5 : Write your code to persist your objects within the DAO
Step 6 : Run your application.
The tutorial guides you through this. You can obtain the code referenced in this
SourceForge (one of the files entitled
The model classes are exactly the same here, so please refer to the
JDO Tutorial for details.
When defining the persistence of the classes, the only difference would be that
we don't need the
since we aren't doing
In the JDO Tutorial we saw that we need to bytecode
enhance our classes to be persisted. This step is identical when using db4o so please
refer to the RDBMS tutorial for details.
With db4o we have no such concept as a "schema" and so this step is omitted.
We saw in the JDO Tutorial how to persist our objects
using JDO API calls. This is the same when using db4o so please refer to the RDBMS
tutorial for details.
We saw in the JDO Tutorial how to run our JDO-enabled
application. This is very similar when persisting to db4o. The only differences are
Put your db4o.jar in the CLASSPATH instead of the JDBC driver
JAR in the CLASSPATH instead of
to include the details for your DB4O
could be like this
As you can see
changing between an RDBMS and db4o is trivial
. The only thing you
change is the URL for persistence! and omit the ORM information.
If you have any questions about this tutorial and how to develop applications for use
please read the online documentation since answers are to be
found there. If you don't find what you're looking for go to our
The DataNucleus Team