Entity Bean Data

While using a separate data store for the actual data, Entity Beans have to use the audit trail to store their primary key value in the data_value table for later dereferentiation of the Entity Bean.

To specify an Entity Bean data:

• Create a new entity bean data model element as described in Specifying Data.
• Open the data properties dialog and select the Entity Bean entry in the data type combo box.
• Select the EJB mode (EJB 2.x or EJB 3.x).

EJB 2.x

Set the following properties:

• Remote Interface Class
• Home Interface Class
• Primary Key Class
• JNDI Path

Figure: Data Properties Dialog for Entity Bean Data

Local Binding

To test a local class as a mock Entity Bean, check the Local binding check box. The implementation has to implement a dummy home class implementation with a create() and a findByPrimaryKey()implementation.

EJB 3.x

The EJB 3.0 mode allows to select a bean class from the Eclipse class browser, satisfying the requirements for an JPA entity bean class.

Access points of the data type are derived from the union of all methods of the business interfaces of this bean class.

Figure: Data Properties Dialog for Entity Bean Data EJB 3.x

The following fields are filled if you select an JPA class with information from the annotations:

• PrimaryKey Type
• PrimaryKey Class
• PrimaryKey Elements

These fields are read only. Please refer to the section Primary Key Examples for detailed examples about the information provided in these fields.

Bean Class

Enter the bean class with the Eclipse class browser entry. Arbitrary classes can selected.

Note that if the selected class does not satisfy the JPA entity requirements an error status is displayed.

Compliance Rules

The following compliance rules for JPA classes are applied to the validation:

• The entity class must have a no-argument constructor. The entity class may have other constructors as well.
• The no-argument constructor must be public or protected.
• The entity class must be a top-level class. An enum or interface should not be designated as an entity.
• The entity class must not be final. No methods or persistent instance variables of the entity class may be final.
• If an entity instance is to be passed by value as a detached object (e.g., through a remote interface), the entity class must implement the Serializable interface.
• Entities support inheritance, polymorphic associations, and polymorphic queries.
• Both abstract and concrete classes can be entities. Entities may extend non-entity classes as well as entity classes, and non-entity classes may extend entity classes.

Entity Manager

The Entity Manager is the main runtime class of the JPA runtime API. The following options are provided to create the Entity Manager:

• JNDI
• FactoryJNDI
• UnitName

Figure: Entity Manager Field

Per default the JNDI lookup is used.

Restrictions

Momentarily the usage of JPA is supported only on JBoss, as for other application servers, e.g. WebLogic, the EntityManagers and EntityManagerFactories cannot be bound in the global JNDI.

In JBoss, the EntityManager and EntityManagerFactories can be bound in the global JNDI by setting appropriate properties in the persistence.xml file, as described in the section Factory JNDI.

JNDI

If you choose JNDI, the Entity Manager is looked up in the JNDI path. Use the JNDI name specified in the persistence-unit part in the persistence.xml file, residing in the WEB-INF folder of your Web application. For example:

    <persistence-unit name="DemoProject">
    ...
    <properties>
        <property name="jboss.entity.manager.jndi.name" value="java:/DemoProject_JPA" /> 
        ...
    </properties>
    </persistence-unit>

Figure: Setting JNDI Properties

Factory JNDI

In case you choose FactoryJNDI, the Entity Manager is accessed from an Entity Manager factory. The name of the factory is specified in the persistence.xml file, e.g.:

<persistence-unit name="DemoProject_JPA">
    ...
    <properties>
        <property name="jboss.entity.manager.jndi.name" value="java:/DemoProject_JPA" /> 
        <property name="jboss.entity.manager.factory.jndi.name" value="java:/DemoProject_JPA_factory" /> 
        ...
    </properties>
</persistence-unit>

Figure: Setting FactoryJNDI Properties

Unit Name

If you choose UnitName, the Entity Manager will be created from the unit name specified in the persistence.xml file, residing in the WEB-INF folder of your Web application. The entry field name JNDI Path changes automatically to Unit Name. For example:

<persistence-unit name="DemoProject_JPA">
    ...
</persistence-unit>

Figure: Setting Unit Name Properties

Primary Key Examples

Simple Id Annotation on a Field

This example uses a bean CustomerBean to demonstrate the simple Id annotation on a field:

@Entity
public class CustomerBean
{
    @Id
    private Long id;
    
    private String name;
    
    public Long getId()
    {
        return id;
    }
    
    public void setId(Long id)
    {
        this.id = id;
    }
    ...
}

The fields are filled with the following information:

Figure: Simple Id Annotation on a Field

Simple Id Annotation on a Property

This example uses a bean ProductBean to demonstrate the simple Id annotation on a property:

@Entity
public class ProductBean
{
    private Long id;
    
    private String name;
    
    private Double price;
    
    @Id
    public Long getId()
    {
        return id;
    }
    
    public void setId(Long id)
    {
        this.id = id;
    }    
    ...
}

The fields are filled with the following information:

Figure: Simple Id Annotation on a Property

Composite Primary Key on Multiple Fields (IdClass)

This example uses a bean OrderBean to demonstrate the composite primary key on multiple fields (IdClass):

@IdClass(OrderPK.class)
@Entity
public class OrderBean
{
    @Id
    private Long customerId;
    
    @Id
    private Long productId;
    
    private Long amount;

    public Long getCustomerId()
    {
        return customerId;
    }

    public void setCustomerId(Long customerId)
    {
        this.customerId = customerId;
    }
    ...
}

The fields are filled with the following information:

Figure: Composite Primary Key on Multiple Fields

Composite Primary Key on a Single Field (EmbeddedId)

This example uses a bean OrderBean2 to demonstrate the composite primary key on multiple fields (IdClass):

@Entity
public class OrderBean2
{
    @EmbeddedId
    private OrderPK pk;
    
    private Long amount;

    public OrderPK getPk()
    {
        return pk;
    }

    public void setPk(OrderPK pk)
    {
        this.pk = pk;
    }
    ...
}

The fields are filled with the following information:

Figure: Composite Primary Key on a Single Field

Instantiating Entity Bean Data Type

Stardust supports instantiation of the entity bean via a bean method creation defined in a session bean application before it can be used as the data type in the process. In the following example, the complete method of the session bean is set to createBmpEntity and then the return value; the created entity bean is set via out data mapping to the entity bean data defined in the model.

public BmpEntity createBmpEntity(String aString) throws RemoteException
   {
      InitialContext ic = null;
      Object obj = null;
      BmpEntity bmpEntity = null;
      try
      {
         ic = new InitialContext();
         obj = ic.lookup("com.example.hydra.entitybean.bmp.BmpEntity");

         BmpEntityHome home = (BmpEntityHome) PortableRemoteObject.narrow(obj,
               BmpEntityHome.class);
         bmpEntity = home.create(aString);
      }
      catch (Exception ex)
      {
         System.out.println(ex.getMessage());
      }
      return bmpEntity;
   }