Presented by developerWorks, your source for great tutorials

ibm.com/developerWorks

I can t stress this point enough. Since EJB 2.0 containers will support the most

common SQL databases (and other data stores as well), you can write components

that work with many types of databases. This makes it easier to sell components that

require persistent storage. For example, you can sell components that will work in an IT

department that uses Oracle or a shop that uses DB2. Thus, instead of writing low level

JDBC calls using SQL native to a particular database, you will use EJB QL to create

finder and select methods, and describe relationships in deployment descriptors.

Simply put, CMP/CMR is the missing link in cross platform component creation.

CMP/CMR will spur the growth of the enterprise level component marketplace. In

addition, CMP/CMR is easier to use then low level JDBC calls. CMP/CMR corrects

many of the foibles, and missing functionality of earlier versions of CMP. There are

many persistence frameworks, none are available on as many application server

platforms as EJB CMP/CMR!

What do I need to know for this tutorial?

The example code in this tutorial is written to work with any J2EE compliant application

server that supports EJB 2.0. The example code endeavors to be compliant; thus, all

example code was deployed on the J2EE reference implementation that ships with

Java 2 SDK, Enterprise Edition 1.3. The example code should deploy to your

application server of choice by just modifying the Ant build scripts and corresponding

deployment descriptors as long as your application server support EJB 2.0, and

therefore, supports CMP/CMR.

This tutorial assumes that you are familiar with Java technology and to some extent

EJB; although, you do not have to be an expert. Since I will be covering deployment

descriptors, which are written in XML, you should have a rudimentary knowledge of

XML. If you are not familiar with EJB, I recommended that you read

Enterprise

JavaBeans Fundamentals

, an developerWorks tutorial written by Richard

Monson Haefel and Tim Rohaly (See

Resources

on page 47 ). This is an excellent

tutorial written by great authors. Even if you do not read this tutorial word for word, I

suggest you at least use it as a reference.

Although not a prerequisite per se, knowledge of

Ant

, an XML based, open source

build system similar to make, will be helpful to understand the build scripts presented in

the examples.

You do not need knowledge of JDBC since there will be no low level calls in this

tutorial, but basic knowledge of SQL and relational database theory is required.

What will this tutorial series cover?

Introducing EJB CMP/CMR, Part 1 of 2

Page 3 of 48