Foreword xi
Preface xiii
Acknowledgments xvii
About the Author xix
Part One An Object-Oriented View on Persistence 1
Chapter 1 A New Generation of Software 3
1.1 From Data to Information 3
1.2 Improving Software Quality 4
1.3 Databases Everywhere 4
1.4 To Have and to Hold 5
1.5 Concentrating on the Essence 5
1.6 The Importance of Scalability 6
1.7 Application Program Interfaces 7
1.8 The Road to Follow 7
Chapter 2 The Database Community Today 9
2.1 Walking among Dinosaurs 9
2.2 Database Usage 10
23 Database Users 10
2.4 Designing Database Applications 11
2.5 Relational Databases 12
2.6 Client/Server Systems 15
2.7 Distributed Software 18
2.8 Problems with Traditional Systems 19
2.9 4GL: The Solution? 20
2.10 Object-Oriented Databases 21
2.11 Preserving Openness 23
2.12 Summary 24
Chapter 3 An Object-Oriented View on Database
Applications 25
3.1 Data-Driven Software Design 25
3.2 Supporting Multiple Applications 28
3.3 Object-Oriented Software Design 29
3.4 The Object Model 30
3.5 Example: Student Administration 31
3.6 Business Models and Supporting Multiple
Applications 34
3.7 C++, Java, or Smalltalk: The Ultimate Answer? 35
3.8 Building Reusable Software 38
3.9 Toward Open Client/Server Applications 40
3.10 Object Orientation and Client/Server Design 40
3.11 User Interfaces 40
3.12 Analogy between User Interfaces and Databases 41
3.13 Object-Oriented or Relational? 43
3.14 Persistence from a Different Angle 44
3.15 Persistence and Separation of Concerns 44
3.16 Safety Issues 46
3.17 Summary 46
Part Two An Architecture for Object Persistence 47
Chapter 4 Making Objects Persistent 49
4.1 Introduction 49
4.2 Basic Requirements of a Persistence Framework 50
4.3 Obtaining Scalability 50
4.4 Interfacing with a Relational World: Problems
to Conquer 51
4.5 Abstracting the Database 57
4.6 An Architecture for Object Persistence 58
4.7 Summary 60
Chapter 5 Abstracting the Database 61
5.1 A Persistent Container Class 61
5.2 Basic Functionality of PSet 61
5.3 Implementing the Persistence Architecture 63
5.4 Resolving the Impedance Mismatch 65
5.5 Reading and Writing Objects 71
5.6 Direct Instances of PSet 73
5.7 Searching for Objects 75
5.8 Supporting Multiple Technologies 79
5.9 Summary 81
Chapter 6 Encapsuiating Data Access 83
6.1 Deriving from PSet 83
6.2 Example: Class City 87
6.3 Using Class ~i ty 93
6.4 Member Objects 93
6.5 Derived IM Resolvers 94
6.6 Class Extension 99
6.7 Compile-Time Decoupling 100
6.8 Reuse and Migration to Other
Technologies 104
6.9 Summary 104
Part Three Implementing Business Models 105
Chapter 7 Designing Business Objects 107
7.1 Developing a Simple Invoicing System 107
7.2 Searching Compound Objects 116
7.3 Object ID versus Primary Key 118
7.4 Developing Generic IM Resolvers 121
7.5 An OID-Based Reference Class 126
7.6 Supporting Existing Database Layouts 130
7.7 Versioning 131
7.8 Stability of Program Code against Schema
Changes 134
7.9 Storing Multimedia Objects 135
7.10 Efficiency 139
7.11 Summary 145
Chapter 8 Inheritance of Persistent Objects 147
8.1 Specialization: Using Inheritance for Reuse 147
8.2 Generalization: Using Inheritance for
Polymorphism 152
8.3 Using Generalizations as Member Objects 158
8.4 Inheritance in Relational Database Systems 162
8.5 Designing Reusable Software Components 170
8.6 Summary 173
Chapter 9 Associations 175
9.1 Many-to-One Relationships 175
9.2 Attributes versus Associations 176
9.3 Collections: One-to-Many Relationships 178
9.4 Associations and Reuse 186
9.5 Many-to-Many Relationships 188
9.6 A Closer Look at Associations 189
9.7 Associations as Independent Entities 191
9.8 Referential Integrity 197
9.9 Summary 202
Chapter 10 Transaction Management and Concurrency
Control 203
10.1 The Transaction 203
10.2 The ACID Test 203
10.3 Transaction Management Exceeds the Database
Level 205
10.4 Concurrency Control: Locking 206
10.5 Example: A Transaction Class 211
10.6 Transactions in Relational Database Systems 212
10.7 Using Transactions 214
10.8 Nested Transactions 215
10.9 Distributed Database Systems 217
10.10 Other Levels of Concurrency 219
10.11 Lock Notification through Call-Back Functions 221
10.12 Summary 222
Chapter 11 The Front End 223
11.1 Analogy between User Interfaces and Databases 223
11.2 Separating the User Interface from the Business
Model 223
11.3 What to Put Where 229
11.4 Navigating through Persistent Sets 229
11.5 Summary 234
Chapter 12 Case Study: An Electronic Telephone Directory 235
12.1 Project Definition 235
12.2 Comparing Development Approaches 236
12.3 Designing the User Interface 237
12.4 The Database Model 240
12.5 Designing the Business Model 240
12.6 Comparing the Business Model and the Database
Model 243
12.7 Implementing the Business Objects 244
12.8 Making Classes Persistent 250
12.9 Impedance Mismatch Examples 257
12.10 Implementing the User Interface 263
12.11 Summary 275
Chapter 13 Toward Open Applications 277
13.1 Third-Party Access to Your Application's
Data 278
13.2 Standard Report Generators and Query
Tools 278
13.3 Informationbases 281
13.4 Interoperability with Other Applications 282
13.5 Implementing an Informationbase 285
13.6 Architecture for Next-Generation Software 286
13.7 Summary 289
Chapter 14 Conclusion 291
Appendix DBtools-Based Implementation of Scoop 293
PSet 293
DataSet 294
IM_Resolver 294
Resolving Impedance Mismatch 295
Building the Select Statement 296
References 297
Index 301
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