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Introduction

XML is now six years old, having been published as a W3C recommendation in February 1998. It was around that time that Oracle began to take a serious look at this new promising technology. In fact the Architectural Review Board decided that XML was going to be of company-wide importance and handed down a development charter to the CORE Development group as follows:

Deliver the best platform for developers to productively build and cost-effectively deploy reliable and scaleable Internet applications exploiting XML.

This charter has proven to be prescient as not only has XML become a dominant Internet technology, but also has spawned an entire family of standards that are becoming the foundation of electronic publishing, business, and application development. The impact of XML has been felt to no greater measure than within Oracle and has kept the now CORE and XML Development group busy these many years. The authors are members of this group and have had the opportunity to not only participate in the XML standards process and produce the implementations but also work with over a hundred development groups across Oracle and countless customers in putting this family of technologies to work in a myriad of ways. Thus we hope to bring to you not only the means to put Oracle’s XML technology to work, but also new ways and new ideas for using XML in your applications.

Over the years, the XML dialog has changed. It used to be asked, when talking with new users or businesses contemplating XML, What is all this fuss about? Why would I want to exchange data in a bloated form having lost its binding? What is the one killer XML application?

These were tough questions, primarily because XML is not an end but a means. Its strength and its weakness are in its ability to be infinitely flexible and extensible. Fortunately, as companion standards such as XSL, XML Schema, Namespaces, XPath, and so on, were developed and rolled out businesses and their developers stopped asking Why XML? and started asking How XML? which leads us to why we wrote this book.

You may be surprised to learn that Oracle does not have a research and development division. All development is done in the context of a product. This can make developing new technologies difficult as these standards efforts evolve, have bugs, and have taken years to stabilize. This can be seen in the years it took to publish XML Schema and that XML Query is in its fifth year and still not out the door. Nevertheless, Oracle has been an early adopter in all of these technologies, putting them to work within all Oracle products.

This situation gave birth to the Oracle XML Developer’s Kit in 1999 as a vehicle to expose implementations of these technologies to both the internal and external development community. This was desirable, as it would allow us to bring these implementations to production quicker using the beta facilities of the Oracle Technology Network (OTN), getting feedback from a broad spectrum of developers looking for XML functionality. Productizing Oracle’s XML infrastructure for external use meant that we had to develop a license. At that time the only Oracle licenses available were either a product license that limited usage to one’s own deployment or a development one that forbid deployment. Neither of these made sense for a software development kit that we weren’t charging for and wanted people to develop against seriously. We were able to successfully navigate Oracle’s legal system to create a deployment and redistribution license for the XDK that exists to this day.

The license wasn’t enough as we were looking for serious enterprise-level development and deployments. We needed support as well. Therefore we again successfully negotiated to have the XDK be included as part of the Oracle server support contracts for the database, application server, and tools at the same service level at no additional charge. Additionally, we were able to offer standalone support agreements for non-Oracle customers. Finally, for those who could not afford or did not need formal support, we opened a support forum on OTN, which has rapidly grown to six forums that we directly support. Over the last five years we have released both beta and production XDKs at roughly three month intervals. Beta versions have a time-based development-only license but the production releases have the full redistribution license.

Finally we come to this book. While this is the third book for two of us, it represents a totally different effort from the previous Oracle XML Handbook and Oracle9i XML Handbook. Those previous editions provided a survey of Oracle and XML and in-depth discussions about the XDK. This edition is totally rewritten with almost all new content. While the previous editions came with CDs, this one does not for two very important reasons. First, all the code in the book will be downloadable from the Oracle Press web site. As distinct from a CD, this allows us to update it should any bugs appear. In the previous editions we provided Oracle software on the CD; however, it forced us to include only Oracle software, so we made most of the code available on OTN. This had the unanticipated effect of lessening the book’s value in some reader’s minds. This edition does not suffer under those limitations, so you will find more original and innovative content and all of the code available for download.

The book is divided into six parts and is organized to be accessible by managers, DBAs, and developers alike. Part I includes Chapters 1 through 7 and focuses on the family of XML standards that are important to Oracle and that should be considered when designing XML-enabled solutions. These not only discuss the common standards of DOM, SAX, XSLT, and XML Schema, but venture into new standards, some of which are not complete, such as XML Query, XML Pipeline, StAX, and JAXB. These chapters are not intended to be comprehensive in their coverage, as whole books have been written on many of them. They do intend to give you a good feel for the functionality offered and to compare and contrast similar standards thus providing guidance in their optimum usage.

Part II includes Chapters 8 through 12 and focuses on XML and the Oracle database. Beginning in Oracle9i Release 2, native XML support was introduced along with significant XML functionality integrated into other database features such as Oracle Text and Advanced Queuing. These chapters provide an in-depth look at this functionality and its evolution into Oracle Database 10g. After getting started in Chapter 8, the chapters are arranged along task lines such as storing XML, retrieving and generating XML, searching and querying XML, and managing the Oracle XML DB. These chapters are designed to be accessible to both developers and DBAs.

Parts III through VI consists of Chapters 13 through 28 and focus on how to use Oracle’s XML technology for real application development. These chapters are split into Oracle’s major development languages of Java, C, C++, and PL/SQL. Each language begins with a getting started chapter covering environment, IDE setup, runtime setup, and so on. The subsequent chapters in these parts discuss real-use case application scenarios. In many instances, these were drawn from actual customer projects. While they include extensive source code, each example is explained in detail and the code is available for download from Oracle Press.

This book was written during the development of Oracle Database 10g and as such could not have been completed without the help of many within Oracle. The authors wish to especially thank the following: