J2EE Design Patterns

Overview

This course will utilize a combination of instructor-led discussions and interactive workshops to illustrate the use of patterns, best practices, design strategies and proven solutions for designing web applications that incorporate JSPs, Servlets, EJBs, JMS and JDBC components. This seminar will focus on the J2EE Patterns Catalog and design strategies that can be utilized to incorporate them. Each of the patterns for the Presentation, Business and Integration tiers will be extensively investigated with an in-depth discussion of the context, problem addressed, forces impacting each, solution provided and the related consequences.

Prerequisites

Each student should have a basic understanding of application development and have been exposed to an object-oriented programming language.

Class Format

Lecture and Lab

Audience

System architects, Java or OO developers, Project Managers and other professionals that will be designing or deploying web applications.

Learning Objectives

After completing this course, the student should be able to:

Understand the concept of J2EE patterns and the Catalog.

Illustrate the J2EE environment and the components affected by implementation of a J2EE pattern.

Discuss the Presentation tier design patterns and their affect on: sessions, client access, validation and consistency.

Depict various bad practices to be avoided when building Presentation tier components.

Discuss the Business tier design patterns and their affect on: Session and Entity EJBs and the use of remote references.

Depict various bad practices to be avoided when building Business tier components.

Understand the variety of implemented bad practices related to the Business and Integration tiers.

Examine the different patterns associated with the Integration tier.

Highlight the evolution of patterns in the implementation of Struts and JavaServer Faces.

Understand the role of J2EE Security

Examine the optimization techniques available in the deployment of J2EE applications in a WebSphere environment.

Depict the role of Cells, Clusters and Application Servers and impact of various patterns on different implementations.

Course Duration

4 Days

Course outline

J2EE Platform

Architecture
- Client tier
- Web tier
- Business tier
- EIS tier
J2EE Components & Containers
Standard API Services (JMS, JDBC, JNDI, etc)
Platform roles
Business Object optimization

J2EE Design Pattern Overview

What are Patterns
Pattern benefits
J2EE Pattern Catalog
- Evolution
- Presentation tier
- Business tier
- Integration tier

Presentation Tier Design Considerations

Model-View-Controller
Tier separation
Design issues
o Session Management
o Client Session state
o Client Session Security issues
o Validation
Bad Practices
o Code control in multiple views
o Expose Presentation-tier data to Business tier
o Duplicate Form Submissions
o Resetting bean properties via setProperty
o Fat Controllers
o Expose resources to direct Client access
o Using Helpers as Scriptlets

Evolution of Presentation Patterns

Struts Architecture
Overview
- Struts Pattern
- Application Components
- Tag usage
JavaServer Faces Architecture
- Overview
- JSF Pattern
- Application Components

Presentation Tier Patterns

Intercepting Filter
- Context
- Problem
- Solution & consequences
Front Controller
- Context
- Problem
- Solution & consequences
View Helper
- Context
- Problem
- Solution & consequences
Composite View
- Context
- Problem
- Solution & consequences
Dispatcher View
- Context
- Problem
- Solution & consequences
Service to Worker
- Context
- Problem
- Solution & consequences

Business Tier Design Considerations

Overview
Role of Session EJBs
- Stateful vs Stateless
- Use in Business-tier Facades
Store State in Business tier
Role of Entity EJBS
Business and Integration tier Bad Practices
- Mapping object model to Entity EJB
- Mapping relational model to Entity EJB
- Use case to Session EJB mapping
- EJB attribute exposure
- Embedded Service lookup in Client tier
- Read-only Entity EJB
- Entity EJB as fine-grained objects
- Exposing EJB exceptions to Client tier
- Large result sets
- EJB and long-lived transactions
- Rebuilding conversation state with Stateless Session EJBs

Business Tier Patterns

Business Delegate
- Context
- Problem
- Solution & consequences
View Object
- Context
- Problem
- Solution & consequences
Session Facade
- Context
- Problem
- Solution & consequences
Business Object
- Context
- Problem
- Solution & consequences
Composite Entity
- Context
- Problem
- Solution & consequences
Transfer Object
- Context
- Problem
- Solution & consequences
Transfer Object Assembler
- Context
- Problem
- Solution & consequences
Value Object Assembler
- Context
- Problem
- Solution & consequences
View List Handler
- Context
- Problem
- Solution & consequences
Service Locator
- Context
- Problem

Integration Tier Patterns

Data abstraction via DAO implementations
- JDO
- SDO
- EJB
- JDBC
Data Access Object
- Context
- Problem
- Forces
- Solution & consequences
Service Activator
- Context
- Problem
- Forces
- Solution & consequences
Domain Store
- Context
- Problem
- Forces
- Solution & consequences
Web Service Broker
- Context
- Problem
- Forces
- Solution & consequences

J2EE Refactoring

Presentation Tier
- Controller
- Synchronizer token
- Localize disparate logic
- Hide presentation
- Remove conversion from client
Business and Integration tier
- Wrap Entity with Session
- Business Delegate
- Merge Session EJBs
- Reduce EJB communication
General Refactoring
- Separate Data access code
- Connection Pool