Java Data Objects

Introduction

Objects have successfully addressed all of the issues to make themselves the basis of a robust, large-scale and malleable development technology--except one. Persistence. In fact, any large scale technology with significant complexity in both the processing and data will hit the problem. Programming languages are not easily given automatic persistence, and database management systems are not very good at organizing processing complexity.

Java has already had one success achieving persistent objects: Enterprise JavaBeans (EJB). The approach of EJB is that of making transactionally secure database entities appear to their clients as Java objects. There is another approach gaining widespread adoption and support -- Java Data Objects (JDO). This is a different, complementary approach: making Java program objects automatically persistent. We also look at how JDO 2, EJB 3 and persistence in general are at long last approaching consitency and interoperability.

Duration and Construction

The course lasts two days. It is based on a cycle of theory-language-practice-review, with approximately two cycles per day. One non-trivial, practical case-study is developed during the course.

Each day will start at 09.00 and finish at 16.30.

Intended Audience

Participants will be practising software engineers who already know and use Java. They may well have attended the Advanced Java course.

Aims

• To understand the nature and difficulties of persistence
• To understand the difficulties of the next generation of databases
• To understand the comparative merits of EJB and JDO
• To understand how EJB 3 and JDO 2 will work with each other
• To understand the JDO architecture
• To understand and use the mechanisms--reachability, descriptors and byte-code enhancers--of JDO
• To understand and practice the persisting of Java objects

Numbers

We recommend that there are no more than 10 participants, each working at his or her own machine.

Deliverables

• Lectures
• Facilitation of discussions
• Direction, assistance and feedback on exercises
• Proposed solutions to the exercises
• Copies of lecture slides, plus explanatory text and summaries
• Reference list of books and sources

Contents

• Objects, databases and persistence
• EJB's approach
• The comparative merits of JDO and EJB
• EJB bean-managed persistence using JDO
• The JDO architecture
• Local persistence
• Enterprise persistence
• XML descriptors
• The JDO life-cycle
• Persistence-by-reachability
• Persistence-aware classes and JDOHelper
• Transaction contexts and JDO
• The bootstrap problem and JDOQL

Site Requirements

• One PC with Java 1.4 (Forte, JBuilder or Cafe) and J2EE, per participant (including one for the lecturer), preferably networked and with a printer
• Data projector with a real 1024 x 768 resolution, and suitable screen
• White-board, preferably not doubling up as the projector's screen; blackboard and chalk are acceptable
• Flip-chart and easel, with additional flip-chart paper

Contacting

Please contact John Deacon by telephone on +44 20 7498 3773; by fax on +44 20 7498 3747; by emailing  jdeacon@jdl.co.uk; or by visiting http://www.jdl.co.uk

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Last modified: Thursday, 08-Feb-2007.
Copyright © 2007 John Deacon. All rights reserved.