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Section 4. Step by step EJB technology example

XDoclet and EJB technology

I started using XDoclet because of EJB technology. It allowed me to port my EJB

components to many J2EE application servers. This is especially important with CMP

as XDoclet generates vendor specific mappings for CMP/CMR to RDBMS. I had my

own EJB code generator written in Jython but my cohort, Erik Hatcher, kept telling me

how great XDoclet was until I finally broke down and tried it.

XDoclet does more than just facilitate porting of EJB components, it also makes EJB

development much easier. How so? Now instead of having 5 or more files for a single

EJB component, you only have one source file to work with. This will make an XDoclet

fan out of any EJB developer.

Think about it. Now instead of maintaining a primary key class, local, and remote

interfaces, local and remote homes, value classes, deployment descriptors, multiple

vendor specific deployment descriptors, and more; I just have one file to maintain. I just

use JavaDoc tags to markup my implementation class and XDoclet takes care of the

rest. This is more than cool. This makes EJB technology easier to use. This helps fulfill

the vision of component architecture.

Some vendors have started supporting XDoclet as part of their tools that ship with the

J2EE application server (JRun). Hopefully this will be a trend. I d love to see IBM and

BEA ship their products with XDoclet support. Currently the vendor specific XDoclet

templates lag behind the release a few months. Don t bother asking for them sooner.

The XDoclet developers will tell you to implement them yourselves. XDoclet is open

source in case you forgot. Actually the templates are pretty easy to modify, perhaps in

a follow up tutorial, I will add CMP/CMR support to some vendors product.

Note if you are an EJB neophyte, there are plenty of resources listed in the resource

section to help you understand this section better. However, this section does assume

some prior experience with EJB technology.

XDoclet is nice for Servlets, really nice for Custom Tags and just about essential for

EJB technology. I ll cover how to use XDoclet with EJB with another step by step

example.

XDoclet and EJB technology continued

Let s define two CMP entity beans (Dept and Employee) that have a one to many

relationship (Dept has many Employees) and a Session bean (HRSystem) that can

Enhance J2EE component reuse with XDoclets

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