Hit the jump for the xml.

<beans>
	<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
        <property name="jndiName" value="jdbc/DB2"/>
        <property name="lookupOnStartup" value="false"/>
        <property name="cache" value="true" />
        <property name="proxyInterface"	value="javax.sql.DataSource" />
    </bean>

    <!-- Hibernate SessionFactory -->
	<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
		<property name="dataSource" ref="dataSource"/>
		<property name="mappingResources">
			<list>
				<value>User.hbm.xml</value>
			</list>
		</property>
		<property name="hibernateProperties">
		    <props>
		      <prop key="hibernate.dialect">org.hibernate.dialect.DB2Dialect</prop>
		      <prop key="hibernate.show_sql">true</prop>
		      <!-- 			IBM WAS SPECIFIC			 -->
		      <prop key="hibernate.connection.datasource">jdbc/DB2</prop>
		      <prop key="hibernate.transaction.factory_class">org.hibernate.transaction.CMTTransactionFactory</prop>
			  <prop key="hibernate.transaction.manager_lookup_class">org.hibernate.transaction.WebSphereExtendedJTATransactionLookup</prop>
			  <!-- 			/END IBM WAS SPECIFIC		 -->
		    </props>
		</property>
	</bean>

	<bean id="transactionManager"
		class="org.springframework.transaction.jta.JtaTransactionManager">
			<property name="autodetectTransactionManager" value="false" />
	</bean>
</beans>

We didn’t want to create an overly large schema for storing objects so when we started getting into subclasses we looked for a solution to handle subclasses and store them in the same table as the superclass. Luckily Hibernate can handle this as well. The only downside to our approach was that we ended up with a table that has columns for all the properties of each subclass with not-null set to false. This means your data integrity will have to reside in your manager objects.

An example hibernate mapping for a super/subclass relationship looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="somepackage.model.DataItem" table="DATA_ITEM" polymorphism="implicit">
<id name="id" column="DATA_ITEM_ID" unsaved-value="0">
<!-- The "increment" generator would hose us in a clustered environment. -->
<generator class="increment" />
</id>
<discriminator column="DISCRIMINATOR" type="string" />

<subclass name="somepackage.model.ReportDataItem" discriminator-value="Report" />

<subclass name="somepackage.model.KpiDataItem" discriminator-value="KPI">
<property name="symbolID" column="SYMBOL_ID" not-null="false" />
</subclass>

</class>
</hibernate-mapping>

As you can see – set the polymorphism attribute to implicit and use the tags to create the mapping. You also need to define the discriminator to tell Hibernate what class to instantiate. In your DAO’s, pull back a list collection and you will have a collection of instances of classes based on your mapping.

The tutorial(s) leave a little to be desired from a custom implementation perspective, but after several emails to the creator (note: send emails to the mailing list, not him directly!) we were able to get past the issues left unclear by the tutorial. The framework makes it so simple to use a private key store to generate a license and then distribute your application with the public key store for verification of the license.

Our implementation in a web application utilizes a servlet filter to read the license file, verify it and then install it. It’s really quite simple and we ended up with only four class files to implement. A SWT client was created to generate the licenses for our purchasing and trial customers.

Another note: the framework also included support for a ‘free trial period’. We chose not to use this as we wanted to keep a strong grasp on where our application was installed, but the ‘ftp’ option looks promising.

Anyone in need of a licensing framework for java, check TLC out!