Professional XML Databases

840 Pages·2000·6.99 MB·English

by  Michael Brundage

Professional XML Databases
KevinWilliams
MichaelBrundage
Patrick Dengler
JeffGabriel
Andy Hoskinson
MichaelKay
ThomasMaxwell
Marcelo Ochoa
Johnny Papa
MohanVanmane
Wrox Press Ltd.
Professional XML Databases
© 2000 Wrox Press
All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted
in any form or by any means, without the prior written permission of the publisher, except in the case of
brief quotations embodied in critical articles or reviews.
The author and publisher have made every effort in the preparation of this book to ensure the accuracy
of the information. However, the information contained in this book is sold without warranty, either
express or implied. Neither the authors, Wrox Press nor its dealers or distributors will be held liable for
any damages caused or alleged to be caused either directly or indirectly by this book.
Published by Wrox Press Ltd,
Arden House, 1102 Warwick Road, Acocks Green,
Birmingham, B27 6BH, UK
Printed in the Canada
ISBN 1861003587
Trademark Acknowledgements
Wrox has endeavored to provide trademark information about all the companies and products
mentioned in this book by the appropriate use of capitals. However, Wrox cannot guarantee the
accuracy of this information.
Credits
Authors Technical Architect
Kevin Williams Jon Duckett
Michael Brundage, Technical Editors
Patrick Dengler Chris Mills
Jeff Gabriel, Andrew Polshaw
Andy Hoskinson, Lisa Stephenson
Michael Kay
Thomas Maxwell, Category Manager
Marcelo Ochoa Dave Galloway
Johnny Papa,
Mohan Vanmane Author Agent
Tony Berry
Technical Reviewers Project Manager
Danny Ayers Avril Corbin
DavidBaliles
Cary Beuershausen Production Manager
Matt Birbeck Simon Hardware
Maxime Bombadier
Bob Cherinka Production Project Coordinator
Michael Corning Mark Burdett
Jeremy Crosbie
Dino Esposito Indexing
Nazir Faisal Alessandro Ansa
Sam Ferguson
Constantinos Hadjisotiriou Figures
Scott Haley Shabnam Hussain
Alex Homer
Michael Kay Cover
Jim Macintosh Shelley Frazier
Craig McQueen
Thomas B. Passin Proof Readers
David Schult Diana Skeldon
Marc H. Simkin Agnes Wiggers
Dave Sussman
Dorai Thodla
Beverley Treadwell
Warren Wiltsie
About the Authors
Kevin Williams
Kevin's first experience with computers was at the age of 10 (in 1980) when he took a BASIC class at a
local community college on their PDP-9, and by the time he was 12, he stayed up for four days straight
hand-assembling 6502 code on his Atari 400. His professional career has been focussed on Windows
development – first client-server, then onto Internet work. He's done a little bit of everything, from VB
to Powerbuilder to Delphi to C/C++ to MASM to ISAPI, CGI, ASP, HTML, XML, and any other
acronym you might care to name; but these days, he's focusing on XML work. Kevin is currently
working with the Mortgage Bankers' Association of America to help them put together an XML standard
for the mortgage industry.
Michael Brundage
Michael Brundage works as a software developer on Microsoft's WebData Internet team, where he
develops XML features for SQL Server 2000. Michael participates actively in the design of the XML
Query Language, producing Microsoft's prototype for the W3C Working Group. Before Microsoft,
Michael was the Senior Software Engineer for NASA's Interferometry Science Center at Caltech, where
he developed networked collaborative environments and a simulation of radiative transfer.
Michael would like to thank his wife Yvonne for her patience; Dave Van Buren, friend and mentor, for
starting it all; Microsoft for allowing him to write; Chris Suver and Paul Cotton for reviewing early
drafts; and everyone at Wrox Press for their help, humor, and flexibility.
Patrick Dengler
Patrick is busily growing Internet startups throughout the "Silicon Forest" area. His interests include
building companies by creating frameworks for Internet architectures. He has received several patents in
stateless Internet database architectures.
I want to thank my lovely, graceful and beautiful wife Kelly for simply putting up with me.
Without her and my family, Devin, Casey, and Dexter, I wouldn't be whole.
Jeff Gabriel
Jeff Gabriel currently works as a developer for eNationwide, the e-commerce arm of Nationwide
Insurance Systems. Jeff is an MCSE, and was formerly a Webmaster before finding the call to be true
geek too strong. He enjoys spending time with his wife Meredith and two children; Max and
Lily. He also likes to read books about technology and computers when not working on same."
Thanks to my family for understanding the long hours it took to write for this book, and my great
desire to do it. I also thank God, who has answered my prayers with many great opportunities.
Finally, thanks to the guys at ATGI Inc. Thanks to Matt for your excellent direction and support
over the years, and to Jason, an incomparable source for all things Java.
Andy Hoskinson
Andy Hoskinson is a senior technical director for a leading Internet professional services firm. He
develops enterprise-class Internet solutions using a variety of technologies, including Java and XML.
Andy is a co-author of Professional Java Server Programming, J2EE Edition (Wrox Press,
Sept. 2000). He is also a co-author of Microsoft Commerce Solutions (Microsoft Press, April 1999), and
has contributed to several different technical publications, including Active Server Developer's Journal
and Visual J++ Developer's Journal.
Andy is a Sun Certified Java Programmer and Microsoft Certified Solution Developer, and lives in
Northern Virginia with his wife Angie. Andy can be reached at [e-mail].
Michael Kay
Michael Kay has spent most of his career as a software designer and systems architect with ICL, the IT
services supplier. As an ICL Fellow, he divides his time between external activities and mainstream
projects for clients, mainly in the area of electronic commerce and publishing. His background is in
database technology: he has worked on the design of network, relational, and object-oriented database
software products – as well as a text search engine. In the XML world he is known as the developer of
the open source Saxon product, the first fully-conformant implementation of the XSLT standard.
Michael lives in Reading, Berkshire with his wife and daughter. His hobbies include genealogy and
choral singing.
Thomas Maxwell
Thomas Maxwell has worked the last few years for eNationwide, the Internet arm of one of the world's
largest insurance companies, developing advanced internet/intranet applications – Many of which
utilized XML databases. He also continues to work with his wife Rene to develop cutting edge Internet
applications, such as the XML based Squirrel Tech Engine, for Creative Squirrel Solutions – a technical
project implementation firm. Tom's technical repertoire includes such tools as Visual Basic, ASP,
COM+, Windows DNA and of course XML. Tom can be reached at [e-mail]
During the writing of this book I became the proud father of my wife's and my first child. So I
would like to thank, firstly my wife for being understanding of my desire to meet the book's
deadlines. And secondly to the staff of Wrox for understanding that a new baby sometimes makes it
difficult to meet deadlines. I would also like to thank the understanding people who helped with the
non-book things that allowed me the time to contribute to this book, including Tom Holquist, who
understands why one may be a little late to the office once in a while and my family including
Marlene and Sharon for helping with Gabrielle in the first few weeks.
Marcelo Ochoa
Marcelo Ochoa works at the System Laboratory of Facultad de Ciencias Exactas, of the Universidad
Nacional del Centro de la Provincia de Buenos Aires and as an external consultant and trainer for Oracle
Argentina. He divides his time between University jobs and external projects related to Oracle web
technologies. He has worked in several Oracle related projects like translation of Oracle manuals and
multimedia CBTs. His background is in database, network, Web and Java technologies. In the XML
world he is known as the developer of the DB Producer for the Apache Cocoon project, the framework
that permits generate XML in the database side.
Summary of Contents
Introduction 1
Chapter 1: XML Design for Data 11
Chapter 2: XML Structures for Existing Databases 47
Chapter 3: Database Structures for Existing XML 67
Chapter 4: Standards Design 111
Chapter 5: XML Schemas 143
Chapter 6: DOM 191
Chapter 7: SAX – The Simple API for XML 241
Chapter 8: XSLT and XPath 285
Chapter 9: Relational References with XLink 347
Chapter 10:Other Technologies (XBase, XPointer, XInclude, XHTML, XForms) 375
Chapter 11:The XML Query Language 409
Chapter 12:Flat Files 431
Chapter 13:ADO, ADO+, and XML 481
Chapter 14:Storing and Retrieving XML in SQL Server 2000 533
Chapter 15:XML Views in SQL Server 2000 581
Chapter 16:JDBC 627
Chapter 17:Data Warehousing, Archival, and Repositories 669
Chapter 18:Data Transmission 701
Chapter 19:Marshalling and Presentation 723
Chapter 20:SQL Server 2000 XML Sample Applications 763
Chapter 21:DB Prism: A Framework to Generate Dynamic XML from a Database 807
Appendix A:XML Primer 863
Appendix B:Relational Database Primer 901
Appendix C:XML Schema Datatypes 915
Appendix D:SAX 2.0: The Simple API for XML 929
Appendix E:Setting Up a Virtual Directory for SQL Server 2000 975
Appendix F:Support, Errata and P2P.Wrox.Com 985
Index 991
Table of Contents
Introduction 1
Why XML and Databases 2
What This Book is About 3
Who Should Use This Book? 3
Data Analysts 3
Relational Database Developers 3
XML Developers 4
Understanding the Problems We Face 4
Structure of the Book 4
Design Techniques 5
Technologies 5
Data Access 6
Common Tasks 6
Case Studies 7
Appendices 7
Technologies Used in the Book 7
Conventions 8
Customer Support 8
Source Code and Updates 8
Errata 9
Chapter 1: XML Design for Data 11
XML for Text Versus XML for Data 12
XML for Text 12
XML for Data 12
Representing Data in XML 14
Element Content Models 14
Element-only Content 14
Mixed Content 14
Text-only Content 15
EMPTY Content 15
ANY Content 16
Using Attributes 16
Other Considerations 17
Audience 17
Performance 17
Data Modeling Versus Representation Modeling 18
XML Data Structures – A Summary 20
Table of Contents
Mapping Between RDBMS and XML Structures 20
Structure 21
Elements 21
Attributes 22
Data Points 22
Our Invoice Using Elements 24
Our Invoice Using Attributes 25
Comparing the Two Approaches 26
Elements or Attributes – The Conclusion 30
Relationships 30
Containment 31
More Complex Relationships – Pointers 32
More Complex Relationships – Containment 34
Relationships – Conclusion 36
Sample Modeling Exercise 37
Before We Begin 37
What is the Scope of the Document? 38
Which Structures Are We Modeling? 38
What Are the Relationships Between Entities? 39
Which Data Points Need to be Associated with Each Structure? 39
Creating the XML DTD 40
Start With the Structures 41
Add the Data Points to the Elements 41
Incorporate the Relationships 41
Sample XML Documents 43
Summary 45
Chapter 2: XML Structures for Existing Databases 47
Migrating a Database to XML 48
Scoping the XML Document 49
Creating the Root Element 51
Model the Tables 51
Model the Nonforeign Key Columns 52
Adding ID Attributes 54
Handling Foreign Keys 55
Add Enumerated Attributes for Lookup Tables 55
Add Element Content to the Root Element 57
Walk the Relationships 58
Add Missing Elements to the Root Element 60
Discard Unreferenced ID attributes 61
An Example XML Document 62
Summary 63
Chapter 3: Database Structures for Existing XML 67
How to Handle the Various DTD Declarations 68
Element Declarations 68
The Element-only (Structured Content) Model 68
The Text-only Content Model 75
The EMPTY Content Model 78
The Mixed Content Model 80
The ANY Content Model 83
ii
Table of Contents
Attribute List Declarations 84
CDATA 84
Enumerated Lists 85
ID and IDREF 87
IDREFS 91
NMTOKEN and NMTOKENS 94
ENTITY and ENTITIES 95
Entity Declarations 96
Notation Declarations 96
Avoid Name Collisions! 96
Summary 97
Example 97
Modeling the Attributes 102
Summary 107
The Rules 107
Chapter 4: Standards Design 111
Scoping the Solution 111
Types of Standards 112
System Internal Standards 112
Cross-system Standards 112
Industry-level Standards 112
Document Usage 113
Archival Documents 113
Transactional Data Documents 115
Presentation Layer Documents 117
Before Diving In: Ground Rules 120
Implementation Assumptions 121
Elements vs. Attributes 121
Restricting Element Content 122
Don't Allow the ANY Element Type 122
Don't Allow the Mixed-content Element Type 123
Constrain Elements that have Structured Content 123
Capturing Strong Typing Information 124
Naming Conventions 125
Understanding the Impact of Design Decisions 126
Performance 126
Document Size 126
Overnormalization 127
Too Many Pointing Relationships 127
Coding Time 129
Document Complexity 130
Pointing Relationships 130
Levels of Abstraction 130
Developer Ramp-up Time 131
Extensibility 131
During the Development 131
Subdividing the Workload 131
Data issues 132
General vs. Specific 132
Required vs. Optional 133
"Tag soup" 133
Keeping the Structure Representation-Independent 133
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