Aspect-Oriented Database Systems

186 Pages·2004·3.82 MB·English

by  Awais Rashid (auth.)

Aspect -Oriented Database Systems
Springer-Verlag Berlin Heidelberg GmbH
Awais Rashid
Aspect -Oriented
Database Systems
With 60 Figures and 17 Tables
, Springer
Awais Rashid
Computing Department, Lancaster University
Lancaster LA1 4YR
United Kingdom
[email protected]
Library of Congress Cataloging-in-Publication Data
Rashid, Awais. Aspect-oriented database systemslAwais Rashid
p.cm. Includes bibliographical references and index.
ISBN 978-3-642-05669-7 ISBN 978-3-662-05851-0 (eBook)
DOI 10.1007/978-3-662-05851-0
1. Database management. 2. Object-oriented programming (Computer science)
3. Databases. I. Title.
QA76.9.D3R322004 005.75'7--dc22 2004061029
ACM Subject Classification (1998): H.2.1, H2.4, D.2.13, D1.5, D.1.m
ISBN 978-3-642-05669-7
This work is subject to copyright. All rights are reserved, whether the whole or part of the material
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© Springer-Verlag Berlin Heidelberg 2004
Originally published by Springer-Verlag Berlin Heidelberg New York in 2004
Softcover reprint of the hardcover 1s t edition 2004
The use of designations, trademarks, etc. in this publication does not imply, even in the absence
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Cover Design: KiinkelLopka, Heidelberg
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Printed on acid-free paper 45/3142 PS 54 32 10
To my school teacher, Mr. Mehboob Malik
Table of Contens
Preface.. ............................................... XI
P.l Outline of the Book. .. .. .. . .. .. .... . . .. . . . . . . . .. . . XII
P.2 Who should Read this Book? .. . . ..... . . . .. . . . . . . .. .. XIII
P.3 Relevant Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. XIV
PA Acknowledgements. . . . .. .. .. .. . .... . . . . .. . . . . . .. .. XIV
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Database Systems .................................. 2
1.1.1 Schema Evolution in Object -Oriented Databases . . . . . . . . 3
1.1.1.1 Class Hierarchy Modification ........................ 3
1.1.1.2 Class Structure Modification . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.1.3 Backward and Forward Compatibility. . . . . . . . . . . . . . . . . 6
1.1.1.4 Need for Dynamic Changes. . . . . . . . . . . . . . . . . . . . . . . . .. 10
1.1.2 Versioning and Workgroup Support .................. 10
1.1.3 Transaction Processing ............................. 12
1.2 Aspect-Oriented Database Systems. . . . . . . . . . . . . . . . . . .. 13
1.2.1 Crosscutting Concerns in Database Systems. . . . . . . . . . .. 13
1.2.2 Fundamentals of Aspect-Oriented Database Systems. . . .. 14
1.2.3 Existing Aspect-Oriented Database Systems ............ 17
1.2.3.1 AODBs using AOP in their Implementation
and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17
1.2.3.2 AODBs Supporting Aspect Persistence ................ 18
1.2.3.3 AODBs or Frameworks Supporting Separation
of Persistence Code from Application Logic... . ... . . . . .. 18
1.2.304 Facets of the Database-AOP Relationship Addressed
by Current AODBs .. .. .. ... .. .. .... . . ... . . ... . . . ... 19
1.3 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19
2. Aspect-Oriented Programming (AOP) ....................... 21
2.1 Separation of Concerns ............................. 21
2.2 Addressing Crosscutting Concerns with AOP . . . . . . . . . .. 23
2.2.1 Aspect Languages .................................. 26
VIII Table of Contents
2.2.2 Composition Filters ................................ 29
2.2.3 Adaptive Programming ............................. 31
2.2.4 Hyperspaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33
2.2.5 Reflective Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34
2.2.6 Hybrid Approach .................................. 35
2.3 Aspect-Oriented Software Development ............... 36
2.4 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37
3. Crosscutting Concerns in Database Systems. . . . . . . . . . . . . . . . . .. 39
3.1 Crosscutting Concerns at DBMS Level ................. 40
3.1.1 Instance Adaptation Approach ....................... 42
3.1.2 Schema Evolution Model . . . . . . . . . . . . . . . . . . . . . . . . . . .. 43
3.1.3 Transaction Model ................................ . 45
3.1.4 Other Crosscutting Concerns at DBMS Level ........... 46
3.2 Crosscutting Concerns at Database Level . . . . . . . . . . . . . .. 46
3.2.1 Links Among Persistent Entities ...................... 47
3.2.2 Versioning Information ............................. 48
3.2.3 Instance Adaptation Routines ........................ 49
3.2.4 Other Crosscutting Concerns at Database Level ......... 51
3.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51
4. Applying AOP in Database Systems. . . . . . . . . . . . . . . . . . . . . . . . .. 53
4.1 A Model for AOP in Database Systems ................. 53
4.2 AOP at DBMS Level ................................ 56
4.2.1 Instance Adaptation Approach ....................... 56
4.2.1.1 Customisable Instance Adaptation in SADES ........... 56
4.2.1.2 Customisable Instance Adaptation in AspOEv .......... 60
4.2.2 Schema Evolution Model . . . . . . . . . . . . . . . . . . . . . . . . . . .. 63
4.2.3 Transaction Model ................................. 64
4.3 AOP at Database Level .............................. 67
4.3.1 Links among Persistent Entities. . . . . . . . . . . . . . . . . . . . . .. 67
4.3.1.3 Overview of SADES Architecture ..................... 67
4.3.1.2 Separation of Links using Composition Filters .......... 70
4.3.1.3 Change Propagation and Referential Integrity. . . . . . . . . .. 76
4.3.2 Versioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 78
4.3.3 Instance Adaptation Routines ........................ 81
4.3.3.4 Instance Adaptation Routines in SADES ............... 81
4.3.3.2 Instance Adaptation Routines in AspOEv .............. 86
Table of Contents IX
4.4 Change Propagation: DBMS Level to Database Level. . . .. 87
4.5 Cost-effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 88
4.6 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 88
5. Persistent Aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 91
5.1 Need for Aspect Persistence. . . . . . . . . . . . . . . . . . . . . . . . .. 91
5.2 Persistent Aspect Stores ............................. 93
5.2.1 An Aspect Store Based on an Object-Oriented Database.. 94
5.2.1.1 PersAJ: An Aspect Store Based on AspectJ and Jasmine... 97
5.2.2 An Aspect Store Based on a Relational Database. . . . . . . .. 99
5.2.2.2 An Aspect Store for AspectJ using SQL-92 Databases. . .. 100
5.3 Aspect Composition in a Persistent Environment ...... 111
5.3.3 Exploiting Composition Mechanisms of Existing
AOP Techniques.................................. 111
5.3.2 Building Composition Mechanisms into the DBMS. . . .. 112
5.3.2.1 Persistent Aspect Structures ........................ 113
5.3.2.2 Weave-on-demand and Weave Histories ............. , 114
5.3.2.3 Weaver for the SADES Object Database
Evolution System ................................. 116
5.4 Applications of Aspect Persistence ................... 117
5.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 117
6. Persistence as an Aspect .................................. 119
6.1 A Bibliography Application. .. . .. .... . . ... . . ... . .... 120
6.2 Aspectising Persistence. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 121
6.2.1 Database Access .................................. 122
6.2.1.1 Connection...................................... 124
6.2.1.2 Storage and Update ............................... 126
6.2.1.3 Retrieval......................................... 127
6.2.1.4 Deletion......................................... 129
6.2.1.5 Transactions ..................................... 130
6.2.1.6 Meta-data Access ................................. 132
6.2.2 SQL Translation .................................. 132
6.2.3 The Emerging Persistence Framework . . . . . . . . . . . . . . .. 136
6.3 Analysis of the Persistence Aspectisation . . . . . . . . . . . . .. 137
6.3.1 Using Other Persistence Mechanisms ................ 137
6.3.2 Reflection and Other AOP Techniques ............... 137
6.3.3 Aspect Interaction ................................ 139
X Table of Contents
6.4 Other Approaches Aspectising Persistence and Related
Concerns ........................................ 140
6.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 142
7. Conclusion and Outlook. . . .. . . . . ... . . . . . . . . . . . . . . . . . . . . .. 145
Abbreviations. .. .. .. .. .. .. . . . . . . . .. . .. .. . . . . . . . . . . . . .. .. 147
References ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 149
Index .................................................. 173
Preface
Database systems are central to the operation of most organisations and
systems today. Over the years promising new developments in software
engineering e.g., object-oriented (00) techniques, have had an impact on
the way we develop, maintain and use database systems. This impact has
ranged from development of new data management mechanisms (in order
to service new programming paradigms e.g., 00) to maintenance tech
niques through to APIs, libraries and frameworks for interacting with the
database from application programs.
A similar promising development is the emerging set of Aspect-Oriented
Software Development (AOSD) techniques. These techniques offer system
atic means to manage crosscutting concerns such as distribution, security
and persistence that cannot be easily modularised using conventional tech
niques such as object-orientation. Such crosscutting concerns also exist in
the context of database systems or applications served by them. It is, there
fore, natural to explore the relationship between database systems and
aspect-oriented techniques in order to determine how database systems
and their applications can benefit from the advanced separation of con
cerns afforded by aspect -orientation. At the same time, it is important to
explore how database systems can support aspect-oriented development in
the same fashion as databases have previously evolved to support object
oriented development.
The term Aspect-Oriented Database Systems (AODBs), therefore, implies
the use of aspect-oriented techniques and database systems in conjunction
with each other. Specifically, in the context of the discussion in this book, it
refers to:
• database systems employing aspect-orientation within their implemen
tation and operation in order to modularise broadly scoped properties,
such as evolution and versioning, with a view to improving customis
ability, extensibility, evolvability and maintainability;