9.1 Introduction

This chapter explores techniques for managing XML document data by exploiting the extensibility features of a modern Object-Relational Database Management System (ORDBMS). The motivation for this prototype system lies in the observation that new applications making use of XML are likely to coexist with preexisting information systems supported by SQL-centric (object-) relational databases. A further goal of the integrated data store described here is to investigate how to preserve all of the desirable quality-of-service features provided by an ORDBMS?read/write ACID transactions, scalability, standard client programming APIs (e.g., JDBC, ODBC), and a declarative data language interface?without compromising the potency of XML as a driver of inter-business communications.

We describe our prototype in cookbook fashion, explaining what its ingredients are and how they were assembled. Production-quality implementations of these ideas could make use of any number of freely available software libraries from the Internet. While this prototype was developed on one object-relational DBMS?namely IBM Informix IDS 9.x-the functionality needed to support its key features is implemented in a number of other DBMS products?notably the Java-based ORDBMS Cloudscape and the Open Source PostgreSQL DBMS?suggesting that the techniques described in this chapter should work equally well in these other systems. In other words, this prototype describes an approach to managing XML that has quite broad utility and does not require any engineering investment on the part of the DBMS vendors. Information systems developers need not wait for vendors to catch up or tolerate proprietary "extensions" to standards that characterize many vendor offerings.

We begin this chapter with an overview of the kind of use-case scenario addressed by our system. XML research is taking a number of divergent paths. Some researchers are focused on the unstructured and partially structured forms of XML, with applications in areas such as content management and information retrieval. This prototype system focuses instead on XML's likely use as an enabler for e-business communication. Pan-enterprise information systems?typified by supply chain management infrastructure?will tend towards much larger numbers of relatively small and more rigorously structured XML "documents" (with and without predefined schema). Participating business organizations will use XML as a lingua franca to exchange structured messages containing quantitative information: what, how much, how many, where, and when. It is thought that e-businesses will be motivated to retain these messages in a query-able repository in order to perform post hoc analysis involving components of the messages for which they had no operational use at the time the message was originally received.

Next, we describe the fairly conventional architecture of our prototype. Our description emphasizes logical architecture?the nature of the software modules making up the system and on the interfaces between them. Briefly, the prototype consists of a database schema that employs a number of SQL-3 user-defined types and functions and a small number of programs that convert XML and XPath into relational data and SQL-3 and back again. This logical architecture can be mapped to several physical architectures. In a modern DBMS, Java class libraries and even compiled binary libraries, which are conventionally integrated within some middleware or client program, can be dynamically linked into the DBMS runtime and treated as a kind of sophisticated stored procedure. Alternatively, the same class libraries may be loaded into middleware or even client programs. Deciding what physical model to adopt is contingent on the specifics of the system under construction.

We then move on to describe several of the more interesting features of the prototype in more detail. The areas of focus are

• The design of the object-relational database schema used by the prototype. Practical applications will need to build upon the simpleminded approach described here, and we suggest ways to employ other ORDBMS techniques to accommodate certain additional features of the XML data model.

• The functionality and design of the new types introduced into the ORDBMS in order to manage hierarchical structures efficiently. We emphasize how the approach taken here meets the requirements of XML XPath processing, how it differs from other proposals, and what is required of the DBMS to support it.

• The algorithms used to convert XPath expressions into their equivalent SQL-3 given the schema design and user-defined types already introduced. XPath expressions constitute a sizeable portion of the XQuery specification. Because XML is conceived as a fundamentally hierarchical data model, getting XPath expressions to run efficiently presents a number of challenges to SQL query processors.

Finally we conclude this chapter with a review of the prototype and a summary of its key contributions.

Top Title TOC Preface P.1 What Is XML? P.2 XML Concepts P.3 XML-Related Technologies P.4 XML Data Management P.5 How This Book Is Organized P.6 Who Should Read This Book P.7 Resources Acknowledgments Chapter 8 Chapter 12 Chapter 13 Chapter 14 Chapter 19 Part I: What Is XML? Chapter 1. Information Modeling with XML 1.1 Introduction 1.2 XML as an Information Domain 1.3 How XML Expresses Information 1.4 Patterns in XML 1.5 Common XML Information-Modeling Pitfalls 1.6 A Very Simple Way to Design XML 1.7 Conclusion Part II: Native XML Databases Chapter 2. Tamino-Software AG's Native XML Server 2.1 Introduction 2.2 Tamino Architecture and APIs 2.3 XML Storage 2.4 Querying XML 2.5 Tools 2.6 Full Database Functionality 2.7 Conclusion Chapter 3. eXist Native XML Database 3.1 Introduction 3.2 Features 3.3 System Architecture Overview 3.4 Getting Started 3.5 Query Language Extensions 3.6 Application Development 3.7 Technical Background 3.8 Conclusion Chapter 4. Embedded XML Databases 4.1 Introduction 4.2 A Primer on Embedded Databases 4.3 Embedded XML Databases 4.4 Building Applications for Embedded XML Databases 4.5 Conclusion Part III: XML and Relational Databases Chapter 5. IBM XML-Enabled Data Management Product Architecture & Technology 5.1 Introduction 5.2 Product and Technology Offering Summaries 5.3 Current Architecture and Technology 5.4 Future Architecture and Technology 5.5 Conclusion Notices Chapter 6. Supporting XML in Oracle9i 6.1 Introduction 6.2 Storing XML as CLOB 6.3 XMLType 6.4 Using XSU for Fine-Grained Storage 6.5 Building XML Documents from Relational Data 6.6 Web Access to the Database 6.7 Special Oracle Features 6.8 Conclusion Chapter 7. XML Support in Microsoft SQL Server 2000 7.1 Introduction 7.2 XML and Relational Data 7.3 XML Access to SQL Server 7.4 Serializing SQL Query Results into XML 7.5 Providing Relational Views over XML 7.6 SQLXML Templates 7.7 Providing XML Views over Relational Data 7.8 Conclusion Chapter 8. A Generic Architecture for Storing XML Documents in a Relational Database 8.1 Introduction 8.2 System Architecture 8.3 The Data Model 8.4 Creating the Database 8.5 Connecting to the Repository 8.6 Uploading XML Documents 8.7 Querying the Repository 8.8 Further Enhancements 8.9 Conclusion Chapter 9. An Object-Relational Approach to Building a High-Performance XML Repository 9.1 Introduction 9.2 Overview of XML Use-Case Scenario 9.3 High-Level System Architecture 9.4 Detailed Design Descriptions 9.5 Conclusion Part IV: Applications of XML Chapter 10. Knowledge Management in Bioinformatics 10.1 Introduction 10.2 A Brief Molecular Biology Background 10.3 Life Sciences Are Turning to XML to Model Their Information 10.4 A Genetic Information Model 10.5 NeoCore XMS* 10.6 Integration of BLAST into NeoCore XMS Conclusion Chapter 11. Case Studies of XML Used with IBM DB2 Universal Database 11.1 Introduction 11.2 Case Study 1: "Our Most Valued Customers Come First" 11.3 Case Study 2: "Improve Cash Flow" 11.4 Conclusion Notices Chapter 12. The Design and Implementation of an Engineering Data Management System Using XML and J2EE 12.1 Introduction 12.2 Background and Requirements 12.3 Overview 12.4 Design Choices 12.5 Future Directions 12.6 Conclusion Chapter 13. Geographical Data Interchange Using XML-Enabled Technology within the GIDB System 13.1 Introduction 13.2 GIDB METOC Data Integration 13.3 GIDB Web Map Service Implementation 13.4 GIDB GML Import and Export 13.5 Conclusion Chapter 14. Space Wide Web by Adapters in Distributed Systems Configuration from Reusable Components 14.1 Introduction 14.2 Advanced Concept Description: The Research Problem 14.3 Integration of Components with Architecture 14.4 Example 14.5 Future Generation NASA Institute for Advanced Concepts, Space Wide Web Research, and Boundaries 14.6 Advanced Concept Development 14.7 Conclusion Chapter 15. XML as a Unifying Framework for Inductive Databases 15.1 Introduction 15.2 Past Work 15.3 The Proposed Data Model: XDM 15.4 Benefits of XDM 15.5 Toward Flexible and Open Systems 15.6 Related Work 15.7 Conclusion Chapter 16. Designing and Managing an XML Warehouse 16.1 Introduction 16.2 Architecture 16.3 Data Warehouse Specification 16.4 Managing the Metadata 16.5 Storage and Management of the Data Warehouse 16.6 DAWAX: A Graphic Tool for the Specification and Management of a Data Warehouse 16.7 Related Work 16.8 Conclusion Part V: Performance and Benchmarks Chapter 17. XML Management System Benchmarks 17.1 Introduction 17.2 Benchmark Specification 17.3 Benchmark Data Set 17.4 Existing Benchmarks for XML 17.5 Conclusion Chapter 18. The Michigan Benchmark: A Micro-Benchmark for XML Query Performance Diagnostics 18.1 Introduction 18.2 Related Work 18.3 Benchmark Data Set 18.4 Benchmark Queries 18.5 Using the Benchmark 18.6 Conclusion Chapter 19. A Comparison of Database Approaches for Storing XML Documents 19.1 Introduction 19.2 Data Models for XML Documents 19.3 Databases for Storing XML Documents 19.4 Benchmarking Specification 19.5 Test Results 19.6 Related Work 19.7 Summary Chapter 20. Performance Analysis between an XML-Enabled Database and a Native XML Database 20.1 Introduction 20.2 Related Work 20.3 Methodology 20.4 Database Design 20.5 Discussion 20.6 Experiment Result 20.7 Conclusion Chapter 21. Conclusion References Contributors Editors Chapter 1: Information Modeling with XML Chapter 2: Tamino-Software AG's Native XML Server Chapter 3: eXist Native XML Database Chapter 4: Embedded XML Databases Chapter 5: IBM XML-Enabled Data Management Product Architecture and Technology Chapter 6: Supporting XML in Oracle9i Chapter 7: XML Support in Microsoft SQL Server 2000 Chapter 8: A Generic Architecture for Storing XML Documents in a Relational Database Chapter 9: An Object-Relational Approach to Building a High-Performance XML Repository Chapter 10: Knowledge Management in Bioinformatics Chapter 11: Case Studies of XML Used with IBM DB2 Universal Database Chapter 12: The Design and Implementation of an Engineering Data Management System Using XML and J2EE Chapter 13: Geographical Data Interchange Using XML-Enabled Technology within the GIDB System Chapter 14: Space Wide Web by Adapters in Distributed Systems Configuration from Reusable Components Chapter 15: XML as a Unifying Framework for Inductive Databases Chapter 16: Designing and Managing an XML Warehouse Chapter 17: XML Management System Benchmarks Chapter 18: The Michigan Benchmark: A Micro-Benchmark for XML Query Performance Diagnostics Chapter 19: A Comparison of Database Approaches for Storing XML Documents Chapter 20: Performance Analysis between an XML-Enabled Database and a Native XML Database Remember the name: eTutorials.org Copyright eTutorials.org 2008-2023. 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