Developing Enterprise JavaBeans

Creating Enterprise JavaBeansTM (EJB) without appropriate tools is a complex process and involves repetitive ways of writing the bean skeleton code, business logic, defining relationships, creating interfaces and specific XML packaging and deployment descriptors.

Studio provides Bean Wizard that eliminates all system-level coding and abstracts the bean creation process to specifying the bean type and writing the business logic.

This document describes the basic approach to writing EJBs in Studio that keeps them in a ready-to-deploy state. Bean Wizard generates source code for EJBs in such a way that it can be included in an assembled application without requiring further source adaptations or recompilation.

Studio allows you to create the following EJBs and their components using the Bean Wizard defined based on EJB 2.0 specification:

Stateless session beans

Stateful session beans

Entity beans with Container Managed Persistence 1.1

Entity beans with Container Managed Persistence 2.0

Entity beans with Bean Managed Persistence

Message Driven Beans

Studio stores beans in EJB modules and Java modules. Express Development keeps the following EJB modules in a ready-to-deploy state:

Organizing beans in a desk

Following elements are displayed under the module in the respective bean package hierarchy:

The business methods are always written in the bean class in Editor. Interfaces are generated automatically and compiled each time a bean is generated, business methods are added, and code compiled.

Bean properties node encapsulates application logic of the bean and describes the enterprise bean and runtime attributes. There can be more than one bean properties node for a single bean class as the node is created for each EJB name of the bean.

The EJB name is used to specify an enterprise bean name which must be unique to the module or JAR.

To open Bean Properties panel, right click on a bean properties node and click Open or double click on the node.

Properties set here get added to the bean when it is added to a JAR; Changes made here do not affect the bean source. Changes in bean code such as removal of get/set methods corresponding to Container Managed Persistence (CMP) and Container Managed Relationships (CMR) are identified when the bean code is compiled. Compiling the bean code reflects the latest CMRs and CMFs in Bean Properties panel.

Respective bean properties are displayed on the left tree. Bean attributes that can be set are:

EJB references

Resource references

Resource environment references for CMP 2.0 beans and MDBs

Transaction attributes

Environment entries

CMP fields for CMP beans

CMR data for CMP 2.0 beans

OR mapping and Map Finder Queries for CMP beans

CMR Data: Stores relationship properties of CMP 2.0 beans. Contains details of relationships between CMP 2.0 beans. Multiplicity and navigability of the relationships can be changed here. Changes made to relation type does not affect the code

OR Mapping: Use the existing tables to map CMFs to the appropriate database attributes. This node is not present in the Packaging tool as it requires input with deploy time information. Specify INSERT strategy for CMP entity beans from the OR mapping panel of Bean Properties or by directly editing the pramati-j2ee-server.xml.

A few other properties that can be set are bean display name, bean class, remote class, home class, local home class, local class, primary key, APS Name, and JNDI name in the main panel of the bean.

Java archive and bean properties

Changes made to the bean in Bean Properties dialog are not reflected in the JAR if the bean concerned has already been added to the JAR. To achieve this, remove the bean from the JAR and add it again. Also, changes made in the JAR do not affect the bean properties globally.

Setting deployment information

Bean Properties dialog allows you to enter deploy time information. Information that can be supplied to bean properties that pertain to Deployment are:

This allows you to specify JNDI name of the EJB reference and resource reference while creating a bean and carries this information forward to the deployment time.

When sources for a bean class is imported into a desk, bean properties node does not get created in the desk corresponding to the imported bean class.

To create bean properties for the Bean Class, right click on the specific Bean source file and select Create Bean Properties.

Enter EJB name for the bean; select bean type. Checking the option Open in Bean Properties creates the Bean Properties on the desk, and opens the Bean Properties panel. Creating Bean Properties in this way, creates properties with partial information.

Cloning feature is used to create beans from the existing beans, with a different EJB name. Having different EJB names gives a different identity to the new bean. Cloning a bean typically consists of creating a copy of bean properties with a new EJBName, and copying all its Java files if required. The resulting bean does not retain finder query mapping for EJB 1.1, OR mapping, and the user has to provide new values if the destination module is the same as the source module. This information is retained if destination module is different from source module.

Source files are not copied if the new bean is in the same module as source bean. In this case only a new bean properties node gets added to the desk.

Advantages of cloning

Cloning can be used for beans with multiple identities that share same properties. For example, AddressBean that encapsulates a real world address can be used in different scenarios such as shipping address, billing address. Each address can be seen as individual beans having same basic properties of AddressBean but different packaging and deployment properties. In such cases, cloning AddressBean result in ShippingAddress and BillingAddress beans

Cloning helps to reuse source code of a bean, and recreate the bean quickly in a different location with all its source-code

Cloning procedure

To clone a bean, right click on bean properties node and select Clone Bean. In the Clone panel, enter the following information:

Table 1:
Attribute	Description
Destination Module	Select an EJB module from the dropdown where the new bean will be stored
Enter EJBName and JNDI Names for Cloned Beans	Displays the bean to be cloned, and allows you to provide a new bean EJB name and JNDI Name. The first column in the table is non-editable and represents EJBName of source bean. The second column displays new EJB names that are to be edited. This can be edited to perform cloning. The third column provides a way to change the JNDI name of target bean
Overwrite Existing Files	Select this option if existing source files are to be overwritten while cloning. This option is available only for source files
Status Box	Displays the status of the cloning operation as it proceeds

The list of destination modules is filtered to prevent the beans from being cloned into folders that cannot accept them. Restrictions include:

Cloning beans from an EJB 2.0 module into an EJB 1.1 module

Cloning beans in a module other than EJB module

If destination module is same as source module, source files are not copied

If two modules point to the same source root, the bean is not copied into source root as the file already exists in that location but it is shown in the new module only. Changes made to the bean or its interfaces in one module are reflected in the bean or interfaces in the other module. If the two modules point to different source roots, the bean is shown in both modules and also copied in the source root. In this case, any changes made in one module are not reflected in the other module

Cloning a CMP 2.0 bean that has relationships with other beans requires all beans along with source bean, to be cloned. In cases where the beans have relationships, all the beans in the CMR Graph are shown. Providing new EJB names ensure that the source and target CMR graphs are complete and ready-to-deploy.

Target bean properties are always written in the file system irrespective of their existence in destination module