<persistence-unit name="library">

      <properties>
         <!-- Scan for annotated classes and Hibernate mapping XML files -->
         <property name="hibernate.archive.autodetection" value="class, hbm" />

         <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver" />
         <property name="hibernate.connection.url" value="jdbc:hsqldb:hsql://localhost:9010/library" />
         <property name="hibernate.connection.username" value="libadmin" />
         <property name="hibernate.connection.password" value="***" />

         <property name="hibernate.c3p0.min_size" value="5" />
         <property name="hibernate.c3p0.max_size" value="20" />
         <property name="hibernate.c3p0.timeout" value="300" />
         <property name="hibernate.c3p0.max_statements" value="50" />
         <property name="hibernate.c3p0.idle_test_period" value="3000" />

         <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect" />

      </properties>
   </persistence-unit>

private EntityManager getEntityManager() {
   return Persistence.createEntityManagerFactory("library")
      .createEntityManager();
}