S A M P L E   P R O J E C T  

The EJB container of an application server also provides some services to the EJB like 

transactions, security or persistence which the programmer / deployer can choose to use or 

not. When we choose to use the container service we speak of  Container Managed  (CM) 

otherwise of  Bean Managed  (BM). The container managed service is normally not as 

powerful as the bean managed service but is defined in the deployment descriptor which 

makes it much more flexible to adjust to another environment. For example the container 

managed persistence allows the programmer to specify a list of persistent attributes which 

the deployer can map at deployment to the table attributes in the target database. This 

means that the same EJB with CMP can work on different tables and / or different 

databases without any changes in the EJB.  

Some of the classes and deployment descriptors contain redundant definitions. Writing this 

files can take much time to create and to maintain and is pretty error prone. There are some 

code generation tools available to help you. Some are based on database structures, is taking 

XML input and other are code based. One of the free tools is XDoclet, which uses JavaDoc to 

define additional information and to generate the additional files. This means that the 

information is kept centralized in the EJB class. So no need to manage home and remote 

interface classes, deployment descriptors, primary keys etc. and they can be regenerated 

when necessary. 

XDoclet normally only needs one file, the EJB implementation, and generates all the other 

necessary files to deploy an EJB. The generated files are: 

EJB and vendor (JBoss, WebLogic, WebSphere, Orion) specific deployment 

descriptors 

Home and Remote Interface 

Primary Key Class for Entity Beans 

Bulk Data Object (also know as Value Object) 

EJB Wrapper classes 

If necessary you can stop the generation of any of these files, you can change the output 

generated and you can add additional code / description as predefined merge points. 

Web and Other Clients 

The best EJBs and resources are worthless if there is no client using it. In J2EE we have 

two types of client, the web client is a composition of servlets and JSPs, which are in the end 

servlets as well, and other clients running outside of the application server. The separation 

is important because web clients can take advantage of running inside the application server 

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