12.5 Future Directions

In this section we look at the future directions of relevant technologies.

12.5.1 XSLT

One of the technologies related to XML that has become a powerful comple mentary tool to use along with XML is the eXtensible Stylesheet Language (XSL). XSL is a language for transforming XML documents and consists of three parts: the XSL language specification itself, XSL Transformations (XSLT), and XML Path (XPath). The combination of XSLT and XPath provides a powerful tree-oriented language for transforming XML documents into other forms including HTML, XML, and PDF. Future versions of the OAI need to provide the client the ability to dynamically select a subset of the fields returned through a query, instead of the full set, which is what is currently returned. The Query Service currently returns query results in the form of an XML document. By processing the user's request to obtain the subset of the selected fields, we can generate the style sheet that can then be used to transform the XML document that includes the full set of fields from the query into an XML document that only includes the client-specified subset. XSLT simplifies the task of transforming the returned document without having to first parse it and regenerate it. This approach is not the most efficient solution for the dynamic field selection problem. It would be more efficient to submit a subset of the original query to obtain the required fields. Our short-term goal is to be able to cache these fixed queries, so that we can at least gain some performance advantage. XSLT in the short run fits our needs best, although we are exploring approaches to efficiently generate dynamically generated queries based on the client-specified fields.

12.5.2 Web Services

Another technology that we plan to explore and possibly utilize in the future is the umbrella of technologies referred to as Web Services. Web Services provide the capability of exporting services to the Web that can be located and accessed by any type of client regardless of their programming language or platform. A Web Service can be as simple as a single method call (such as get the stock price for a given symbol) or a complicated business process. The current set of technologies that form Web Services consists of SOAP, XML Schema, WSDL, and UDDI. The Simple Object Access Protocol (SOAP) is an XML-based protocol for making Remote Procedure Calls (RPCs). The Web Services Description Language (WSDL) is used to describe the service and how to invoke it, and serves a similar purpose as the IDL for a CORBA service. Universal Discovery Description Integration (UDDI) is a standard-based service for exporting Web Services by the service provider and for locating them for the clients.

Using Web Services fits very nicely with some of the requirements of OAI. The platform and language-independence features of Web Services will resolve our requirement of having to support multiple heterogeneous clients. The ability to export services across the Internet will help us meet the requirement of having to support the exchange of image data across repositories in a secure way.

12.5.3 Mass Transfer Capability

A future enhancement of OAI will require for the mass transfer of JEDMICS data between sites and/or external applications. Importing/exporting complete engineering drawings and collections, including all cross-reference associations and the image data itself from remote OAI sites is of major importance to the JEDMICS community. JEMDICS sites need to be able to easily share their data.

Currently, JEDMICS provides several tools to allow the bulk transfer of information (both index data and image files) between JEDMICS sites. However, the current tools are intended for use by the JEDMICS system administrative staff and require the user to run several different applications to define, assemble, export, and finally import the data from the remote JEDMICS site into the local JEDMICS site. It is because of these limitations that a new, consolidated approach is needed for the end users and system administrators. Defining the JEDMICS data as XML documents provides for a platform- and language-independent means of transferring this data. The XML document is easily read and understood and is parsable by any client application. Without the use of XML, OAI would need to develop a proprietary data interchange format, which would not be easily manipulated by external clients.

12.5.4 Messaging

Messaging is a method of communication between software components or applications. Messaging enables distributed communication that is loosely coupled, which means that the sender and receiver do not need to know about each other. A messaging system makes the best effort to deliver messages asynchronously and reliably. Reliability means that messages are delivered to the client once and only once. Asynchronous means that the provider can deliver messages to the client as they arrive, and the client does not have to request messages in order to receive them. It also means that both clients and providers do not need to wait until messages are received, processed, or sent. Clients can continue with other tasks while the message request is processed in the background. This is very useful, especially when the client needs only to make sure that the request will be processed and not necessarily when the request has been processed.

It would be useful for the future release of OAI to incorporate messaging capability into the system. One such use may be applied to the printing bean, where sometimes a print job is associated with many images (and therefore involves many data files), and where delays might be associated with the print queue. Therefore, it makes sense for the clients to be able to submit print jobs once and be assured that they will get printed, without having to wait. The current JEDMICS system already has the capability to query and produce reports on print jobs submitted, and this capability will still be in use when the messaging is utilized.

There are two ways by which messaging can be done in the context of the OAI system:

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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