In the TABLE_PER_CLASS strategy, hibernate will create a separate table for all the classes in an inheritance hierarchy. It is still not normalized completely as inherited columns are repeated in all tables. For instance, Fields inherited from Shape such as id and fillcolor are repeated in all the tables.

In this example, we will create and save three entity classes – Shape, Rectangle and Circle; where Rectangle and Circle extends from Shape.

In the SINGLE_TABLE strategy, hibernate will create a single table for all the classes in an inheritance hierarchy. There will be a discriminator column that tells us the class to which that row belongs.

In this example, we will create and save three entity classes – Shape, Rectangle and Circle; where Rectangle and Circle extends from Shape.

EJBs can serve as endpoints for SOAP based web services if hosted in a container with runtime and service support. New client applications can then be built using the published WSDL to access existing business logic. New remote clients can also continue to access business logic using RMI. Thus clients will have now a choice to use RMI or web services to access the business logic.

There are primarily four types of EJBs:

• Stateful session bean

SOAP message handlers enable Web Services and clients to perform additional processing on the SOAP message request or response, by intercepting the SOAP message in both the request and response of the Web Service. 

SOAP handlers and logical handlers

• JAX-WS supports two types of SOAP message handlers:

  • SOAP handlers

When referencing entities from other entities, we are mapping two entities whereas when referencing a value type we are embedding (or containing) a value type within an entity.

When mapping two entities, we annotate both classes as @Entity, and the mapping type is specified using the annotations @OneToOne, @OneToMany, @ManyToOne or @ManyToMany, over the reference variable declaration of an entity in another entity.

We will consider two entities for mapping examples – a student class and a course class.