Automatic Table Generation in the roster Application

At deploytime the Application Server will automatically drop and create the database tables used by roster. This is done by setting the toplink.ddl-generation property to drop-and-create-tables in persistence.xml.

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
    <persistence-unit name="em" transaction-type="JTA">
        <jta-data-source>jdbc/__default</jta-data-source>
        <properties>
            <property name="toplink.ddl-generation"
                             value="drop-and-create-tables"/>
        </properties>
    </persistence-unit>
</persistence>

This feature is specific to the Java Persistence API provider used by the Application Server, and is non-portable across Java EE servers. Automatic table creation is useful for development purposes, however, and the toplink.ddl-generation property may be removed from persistence.xml when preparing the application for production use, or when deploying to other Java EE servers.