Creating an EJB with the wizard

Chapter 14 Working with Java

Creating an EJB with the wizard

You can create an EJB component with the wizard that will guide you through the creation of the component. It is only available if the language is Java.

The wizard is invoked from a class diagram. You can either create an EJB without selecting any class, or select a class first and start the wizard from the contextual menu of the class.

You can also create several EJBs of the same type by selecting several classes at the same time. The wizard will automatically create one EJB per class. The classes you have selected in the class diagram become the Bean classes. They are renamed to fit the naming conventions standard, and they are linked to their component.

If you have selected classes or interfaces before starting the wizard, they are automatically linked to the new EJB component.

When an interface or a class is already stereotyped, like <<EJBEntity>> for example, it is primarily used to be the interface or the class of the EJB.

For more information on stereotyped EJB interface or class, see section Defining interfaces and classes for EJBs.

The EJB creation wizard lets you define the following parameters:

Property	Description
Name	Name of the EJB component
Code	Code of the EJB component
Component type	Entity Bean CMP, Entity Bean BMP, Message Driven Bean, Session Bean Stateful, or Session Bean Stateless For more information on the different types of EJB, see section Using EJB types
Bean class	Class implementing the bean business methods
Remote interface	Extends the javax.ejb.EJBObject interface and provides the remote client view
Remote home interface	Defines methods and operations used in a remote client view. It extends the javax.ejb.EJBHome interface
Local interface	Extends the javax.ejb.EJBLocalObject interface, and allows beans to be tightly coupled with their clients and to be directly accessed
Local home interface	Defines methods and operations used locally in a local client view. It extends the javax.ejb.EJBLocal-Home interface
Primary key class	Class providing a pointer into the database. It is only applicable to entity beans
Transaction	Defines what transaction support is used for the component. The transaction is important for distribution across a network on a server. The transaction support value is displayed in the deployment descriptor. This information is given by the deployment descriptor to the server when generating the component
Create symbol	Creates a component symbol in the diagram specified beside the Create symbol In check box. If a component diagram already exists, you can select one from the dropdown listbox. You can also display the diagram properties by selecting the Properties tool
Create Class Diagram for component classifiers	Creates a class diagram with a symbol for each class and interface. If you have selected classes and interfaces before starting the wizard, they are used to create the component. This option allows you to display these classes and interfaces in a diagram

The Transaction support groupbox contains the following values, as per the Enterprise JavaBeans 2.0 specification from Sun Microsystems, Inc.

Transaction value	Description
Not Supported	The component does not support transaction, it does not need any transaction and if there is one, it ignores it
Supports	The component is awaiting a transaction, it uses it
Required	If there is no transaction, one is created
Requires New	The component needs a new transaction at creation, the server must provide it with a new transaction
Mandatory	If there is no transaction, an exception is thrown
Never	There is no need for a transaction

The EJB deployment descriptor supports transaction type for each method: you can specify a transaction type for each method of EJB remote and local interface.

You can define the transaction type for each method using an extended attribute from the Profile/Operation/Extended Attributes/EJB folder of the Java object language. If the transaction type of the operation is not specified (it is empty), the default transaction type defined in the component is used instead.

To create an EJB with the wizard:

Select Tools→Create Enterprise JavaBean from a class diagram.

The Enterprise JavaBean Wizard dialog box appears.

Type a name and code for the component and click Next.

Steps of the wizard
If you have selected classes before starting the wizard, some of the following steps are omitted because the different names are created by default according to the names of the selected classes.

Select the component type and click Next.

Select the Bean class name and click Next.

Select the remote interface and the remote home interface names and click Next.

Select the local interface and the local home interface names and click Next.

Select the primary key class name and click Next.

Select the transaction support and click Next.

At the end of the wizard, you have to define the creation of symbols and diagrams.

When you have finished using the wizard, the following actions are executed:

An EJB component is created
Classes and interfaces are associated with the component, and any missing classes or interfaces associated with the component are added
Any diagrams associated with the component are created or updated
Depending on the EJB type, the EJB primary key class, its interfaces and dependencies are automatically created and visible in the Browser. In addition to this, all dependencies between remote interfaces, local interfaces and the Bean class of the component are created
The EJB created is named after the original class if you have selected a class before starting the wizard. Classes and interfaces are also prefixed after the original class name to preserve coherence