Enterprise Java with UML

Enterprise Java™

with UML™

CT Arlington

Wiley Computer Publishing

John Wiley & Sons, Inc.

NEW YORK • CHICHESTER • WEINHEIM • BRISBANE • SINGAPORE • TORONTO

To my beautiful wife Anne, you were sooo worth the wait!

Always and forever,

To Bethany Carleen, our precious daughter, and my

personal trainer.

To Anne Burzawa, my best friend from cradle to grave.

Publisher: Robert Ipsen

Editor: Theresa Hudson

Developmental Editor: Kathryn A. Malm

Managing Editor: Angela Smith

Text Design & Composition: Publishers' Design and Production Services, Inc.

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This book is printed on acid-free paper. ©

Copyright © 2001 by CT Arrington. All rights reserved.

Published by John Wiley & Sons, Inc.

Published simultaneously in Canada.

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engaged in professional services. If professional advice or other expert assistance is

required, the services of a competent professional person should be sought￾Library of Congress Cataloging-in-Publication Data:

ISBN: 0-471-38680-4

Printed in the United States of America.

10 9876543 2

Contents

OMG Press Advisory Board xvii

OMG Press Books in Print xix

About the OMG xxi

Chapter 1 Introduction to Modeling Java with the UML 1

What Is Modeling? 2

Simplification 3

Varying Perspectives 3

Common Notation 4

UML 4

The Basics 4

Modeling Software Systems with the UML 13

The Customer's Perspective 13

The Developer's Perspective 14

Modeling Process 14

Requirements Gathering 15

Analysis 15

Technology Selection 15

Architecture 15

Design and Implementation 16

The Next Step 16

Chapter 2 Gathering Requirements with UML 17

Are You Ready? 18

What Are Good Requirements? 18

Find the Right People 19

Listen to the Stakeholders 20

Develop Accessible Requirements 21

Describe Detailed and Complete Requirements 24

III

iv Contents

Refactor the Use Case Model 27

Guidelines for Gathering Requirements 34

Focus on the Problem 34

Don't Give Up 35

Don't Go Too Far 35

Believe in the Process 36

How to Detect Poor Requirements 37

Path 1: Excessive Schedule Pressure 38

Path 2: No Clear Vision 39

Path 3: Premature Architecture and Design 40

The Next Step 40

Chapter 3 Gathering Requirements for the Timecard Application 41

Listen to the Stakeholders 42

Build a Use Case Diagram 44

Find the Actors 44

Find the Use Cases 45

Determine the Actor-to-Use-Case Relationships 47

Describe the Details 48

Guidelines for Describing the Details 48

Gathering More Requirements 58

Revising the Use Case Model 61

Revise the Use Case Diagram 61

Revising the Use Case Documentation 63

The Next Step 75

Chapter 4 A Brief Introduction to Object-Oriented Analysis

with the UML 77

Are You Ready? 78

Solid Requirements 78

Prioritizing Use Cases 78

What Is Object-Oriented Analysis? 80

The Analysis Model 80

Relationship to Use Case Model SO

Steps for Object-Oriented Analysis 81

Discover Candidate Objects 81

Guidelines for Discovering Objects 81

Process for Discovering Objects 83

Describe Behavior 90

Guidelines for Finding Behavior 90

Contents v

A Process for Describing Behavior 92

Describe the Classes 95

Guidelines for Describing Classes 95

Process for Describing Classes 97

The Next Step 101

Chapter 5 Analysis Model for the Timecard Application 103

Prioritizing the Use Cases 103

The Ranking System 104

Evaluation of the Export Time Entries Use Case 107

Eva uation of the Create Charge Code Use Case 108

Eva uation of the Change Password Use Case 109

Eva uation of the Login Use Case 109

Eva uation of the Record Time Use Case 110

Eva uation of the Create Employee Use Case 111

Select Use Cases for the First Iteration 112

Discover Candidate Objects 112

Discover Entity Objects 113

Discover Boundary Objects 116

Discover Control Classes 118

Discover Lifecycle Classes 118

Describe Object Interactions 118

Add Tentative Behavior for Login 119

Build Sequence Diagrams for Login 119

Validate Sequences for Login 122

Sequence Diagrams and Class Diagrams for the

Remaining Use Cases 124

Describe Classes 126

Find Relationships for Login 127

Find Relationships for Export Time Entries 128

Find Relationships for Record Time 129

The Next Step 131

Chapter 6 Describing the System for Technology Selection 133

Are You Ready? 134

Group Analysis Classes 134

Boundary (User Interface) 134

Boundary (System Interface) 136

Control, Entity, and Lifecycle 136

Describe Each Group 136

User Interface Complexity 137

vi Contents

Deployment Constraints for User Interfaces 138

Number and Type of Users 140

Available Bandwidth 141

Types of System Interfaces 142

Performance and Scalability 143

Technology Requirements for the Timecard Application 144

Find Groups of Analysis Classes 144

User Interface Complexity 144

Deployment Constraints for User Interfaces 146

Number and Type of Users 147

Available Bandwidth 148

Types of System Interfaces 148

Performance and Scalability 148

The Next Step 152

Chapter 7 Evaluating Candidate Technologies for Boundary Classes 153

Technology Template 153

Swing 154

Gory Details 155

Strengths 165

Weaknesses 165

Compatible Technologies 165

Cost of Adoption 166

Suitability 167

Java Servlets 168

Gory Details 170

Strengths 172

Weaknesses 172

Compatible Technologies 172

Cost of Adoption 172

Suitability 173

XML 175

Gory Details 176

Strengths 178

Weaknesses 178

Compatible Technologies 178

Cost of Adoption 178

Suitability 179

Contents vii

Technology Selections for the Timecard System 180

User Interface Classes 180

Conclusion 181

The Next Step 182

Chapter 8 Evaluating Candidate Technologies for Control and

Entity Classes 183

RMI 183

Gory Details 184

Common Uses of RMI 188

Strengths 192

Weaknesses 192

Compatible Technologies 192

Cost of Adoption 192

JDBC 193

Gory Details 193

Strengths 196

Weaknesses 197

Compatible Technologies 198

Cost of Adoption 198

Suitability of RMI and JDBC 198

ETB 1.1 199

Gory Details 202

Strengths 205

Weaknesses 206

Compatible Technologies 206

Cost of Adoption 206

Suitability 207

Sampie Technology Selection 208

Technology Requirements 208

The Next Step 210

Chapter 9 Software Architecture 211

Are You Ready? 212

Clear Understanding of the Problem 212

Clear Understanding of the Technology 212

Goals for Software Architecture 213

Extensibility 213

Maintainability 213

viii Contents

Reliability 214

Scalability 214

UML and Architecture 214

Packages 214

Package Dependency 217

Subsystems 219

Guidelines for Software Architecture 221

Cohesion 222

Coupling 222

Creating a Software Architecture 222

The Architect 222

A Process 223

Sample Architecture for the Timecard System 225

Set Goals 225

Group and Evaluate Classes 226

Show Technologies 233

Extract Subsystems 233

Evaluate against Guidelines and Goals 233

The Next Step 237

Chapter 10 Introduction to Design 239

What Is Design? 239

Are You Ready? 240

The Need for Design 240

Productivity and Morale 240

A Malleable Medium 241

Scheduling and Delegation 241

Design Patterns 241

Benefits 242

Use 243

Planning for Design 243

Establish Goals for the Entire Design 244

Establish Design Guidelines 245

Find Independent Design Efforts 246

Designing Packages or Subsystems 246

Design Efforts for the Timecard Application 247

The Next Step 248

Chapter 11 Design for the TimecardDomain and

TimecardWorkflow 249

Contents IX

Establish Goals for the Effort 250

Performance and Reliability 250

Reuse 250

Extensibility 250

Review Prior Steps 251

Review of the Analysis Model 251

Review Architectural Constraints 257

Design for Goals 258

Apply Design for Each Use Case 262

Design for the Login Use Case 262

Design for the Record Time Use Case 266

Design for the Export Time Entries Use Case 271

Evaluate the Design 273

Implementation 277

User Entity Bean 277

Timecard Entity Bean 283

LoginWorkflow Stateless Session Bean 292

RecordTimeWorkflow Stateful Session Bean 296

Supporting Classes 301

ChargeCodeHome 308

ChargeCodeWrapper.java 319

Node.java 320

The Next Step 321

Chapter 12 Design for HTML Production 323

Design Goals 324

Goal 1: Support Modular Construction of Views 324

Goal 2: Keep HTML Production Simple 324

Goal 3: Support Preferences 326

Goal 4: Extensibility and Encapsulation 326

Design to Goals 327

Design for Goal 1: Support Modular Construction

of Views 327

Design for Goal 2: Keep HTML Production Simple 330

Design for Goal 3: Support Preferences 335

Design for Goal 4: Extensibility and Encapsulation 338

Filling in the Details 339

Implementation 346

IHtmlProducer.java 346

ComboBoxProducer.java 347

X Contents

FormProducer.java 348

PageProducer.java 350

SubmitButtonProducer 351

TableProducer.java 352

TabularlnputFormProducer.java 354

TextFieldProducer.java 356

TextProducer.java 358

IConcreteProducer.java 359

ProducerFactory.java 360

FormProducerGeneric.java 364

PageProducerGeneric.java 366

TableProducerGeneric.java 368

TabularTnputFormProducerGeneric.java 369

The Next Step 371

Chapter 13 Design for the TimecardUl Package 373

Establish Design Goals 373

Extensibility 373

Testability 374

Review Prior Steps 374

Review Architectural Constraints 374

Review Analysis Model 375

Design to Goals 379

Design for Each Use Case 381

Create Design for the Login Use Case 381

Create Design for the Record Time Use Case 383

Implementation 387

LoginServlet.java 387

RecordTimeServlet.java 392

BaskServlet.java 397

The Next Step 399

Chapter 14 Design for Bill! ngSystem Interface 401

Identify Goals 401

Clarity 402

Performance and Reliability 402

Extensibility 402

Reuse Potential 402

Review of Analysis Model 402

Review of Architecture 402

Contents XI

Design 403

Sequence Diagram for Export Specific Users 406

Sequence Diagram for Export All Users 406

Participating Classes 406

Implementation 407

ExportCriteria.java 407

ExportFile.java 412

Exp or tTimeEntr ie s A pplic ation.java 414

Conclusion 417

Appendix A Visual Glossary 419

Appendix B Additional Resources 435

Appendix C The CD-ROM 439

Index 441

Acknowledgments

Thanks to all of my former coworkers and bosses at Number Six Software,

for their support, reviews, and insights. Special thanks are due to the

cofounders, Rob Daly and Brian Lyons, for creating an amazing environ￾ment in which to work and to stretch professionally. Special thanks to

Susan Cardinale, Greg Gurley, Kevin Puscas, Hugo Scavino, and Eric

Tavella for their feedback and encouragement.

Thanks to John Haynes for his careful review and commentary.

Thanks to Mike Janiszewski and Jennifer. Horn, for their review, encourage￾ment, and support. Friends in need are friends in deed.

Many thanks to the fine professionals from John Wiley and Sons; Terri Hud￾son, Kathryn Malm, Angela Smith, Janice Borzendowski, and Brian

Snapp. Kathryn deserves special recognition for her ability to edit techni￾cal material while keeping an exhausted author motivated.

Thanks to the Wrights, for their consistent friendship, encouragement, and

lawn advice. We couldn't ask for better neighbors.

Thanks to my parents, for fostering a lifetime obsession with the printed

word.

I will never be able to sufficiently thank my family for permitting me this

most selfish endeavor. How many evenings and weekends did I take

away? How many mornings did T wake bleary eyed and grumpy from too

little sleep and too little progress? This book truly was a once in a lifetime

opportunity for the skinny (formerly) kid who read too much, and you

two made it possible. Thank you!

xiii

About the Author

CT Arlington has spent the last nine years developing client-server software

systems ranging from currency options valuation to barge scheduling to com￾plex corporate intranets. Over the last five years, he has become convinced

that the combination of Object Oriented Analysis and Design and good Soft￾ware Engineering practices can yield excellent systems in a sane work

environment.

CT's focus over the last few years has been architecting and developing sys￾tems in Java. These tended to be 3+ tier server side applications for use in cor￾porate intranets. His favorite technologies for such systems include Servlets,

XML, EJB, and Object to Relational persistence frameworks. He also had the

good fortune to be the lead developer for a slick Java data visualization tool for

barge scheduling. This project used Swing and a commercial 2D graphics

framework and convinced him that Java applications can meet demanding

performance goals.

In these pursuits, CT has depended heavily on books on OO design, design

patterns, software engineering, Java, CORBA, EJB, and XML. While he has

read and enjoyed many great books over the years, he cannot imagine devel￾oping software without Grady Booch's OOAD with Applications, the Gang of

Four's Design Patterns, Steve McConnell's Rapid Development and of course,

Patrick Chan's The Java Class Libraries.

CT is an architect and development manager with Capital One in Northern

Virginia.

CT is a former Rational Software certified instructor and a Sun certified Java

Programmer, Developer, and Architect. He holds a Bachelor's in Applied

Mathematics from the University of Maryland at Baltimore County.

xv

OMG Press Advisory Board

Karen D. Boucher

Executive Vice President

The Standish Group

Carol C. Hurt

President and Chief Executive Officer

2AB, Inc.

Ian Foster

Business Director

Concept Five Technologies

Michael Gurevich

Chief Architect

724 Solutions

V. "Juggy" Jagannathan, Ph.D.

Senior Vice President of Research and Development

and Chief Technology Officer

CareFlow! Net, Inc.

Cris Kobryn

Chief Scientist and Senior Director

Inline Software

Nilo Mitra, Ph.D.

Principal System Engineer

Ericsson

Richard Mark Soley, Ph.D.

Chairman and Chief Executive Officer

Object Management Group, Inc.

xvii

Introduction to Modeling

Java with the UML

As Java completes its move from a novelty language to the language of choice for Web￾enabled enterprise computing, Java developers are faced with many opportunities as

well as many challenges. We must produce systems that scale as the underlying busi￾ness grows and evolves at Web speed. Our customers' appetite for functionality, scala￾bility, usability, extensibility, and reliability rises each year.

Fortunately, Java provides a lot of support as we struggle to meet these demands.

First and perhaps foremost, Java is a small, tightly written object-oriented language

with excellent support for exception handling and concurrency built in. Of course, this

language runs on a pi a tform-independent virtual machine that allows Java systems to

run on everything from a PalmPilot to a Web browser to an AS400, with about a dozen

operating systems in between. From this solid foundation. Sun built and evolved one

of the most impressive class libraries you could ever ask for, including support for

internationalization, calendar management, database access, image manipulation, net￾working, user interfaces, 2D and 3D graphics, and more. Finally, Enterprise JavaBeans

and Java 2 Enterprise Edition provide specifications for true cross-platform enterprise

computing. Many of the problems that have plagued enterprise developers for decades,

such as object-to-relational persistence, object caching, data integrity, and resource

management are being addressed with newfound vigor. These specifications, and the

application servers that implement them, allow us to leverage a wealth of academic

research and practical experience. We are better equipped to develop enterprise sys￾tems than ever before.

1