Sams Teach Yourself XML in 21 Days
(Publisher: Macmillan Computer Publishing)
Author(s): Simon North
ISBN: 1575213966
Publication Date: 04/13/99

Introduction

XML started as an obscure effort driven by a small group of dedicated SGML experts who were convinced that the world needed something more powerful than HTML. Although XML hasn’t yet taken the world by storm, in its quiet way it is poised to revolutionize the Internet and usher in a new age of electronic commerce.

Until recently, the non-technical Internet user has largely written off XML as being more of a programmers’ language than a technology that applies to us all. Nearly two years after XML’s inception, there is still no real mainstream software support in the form of editors and viewers. However, just as with HTML, as the technology becomes adopted, the tools will start to arrive. Netscape and Microsoft have already given us a taste of what is to come.

Sams Teach Yourself XML in 21 Days teaches you about XML and its related standards (the XSL style language, XLink and XPointer hyperlinking, XML Data, and XSchema, to name just a few), but it doesn’t stop there. As you follow the step-by-step explanations, you will also learn how to use XML. You will be introduced to a wide range of the available tools, from the newest to the tried and tested. By the time you finish this book, you’ll know enough about XML and its use within the available tools to use it immediately.

How This Book Is Organized

Sams Teach Yourself XML in 21 Days covers the latest version of XML, its related standards, and a wide variety of tools. Some features of the tools will have been enhanced or expanded by the time you read this, and new tools will certainly have become available. Keep this in mind when you’re working with the early versions of some of the software packages. If something doesn’t work as it should, or if you feel that there is something important missing, check the Web sites mentioned in Appendix B, “XML Resources,” to see if a newer version of the package is available.

Sams Teach Yourself XML in 21 Days is organized into three separate weeks. Each week brings you to a certain milestone in your learning of XML and development of XML code.

In the first week, you’ll learn a lot of the basics about XML itself:

•  On Day 1, you’ll get a basic introduction on what XML is and why it’s so important. You will also see your first XML document.

•  On Day 2, you will dissect an XML document to discover exactly what goes into making usable XML code. You will also create your first XML document.

•  On Day 3, you’ll go a little further into the basics of XML code. You’ll learn about elements, comments, processing instructions, and using CDATA sections to hide XML code you don’t want to be processed.

•  On Day 4, you will learn more about markup and elements by exploring attributes. You’ll also learn the basics of information modeling and some of the ground rules of Document Type Definition (DTD) development. You will learn how to work with DTDs without having to go as far as creating valid XML code, and you will discover how much you can already achieve by creating well-formed XML documents.

•  On Day 5, you’ll reach an important milestone. You will learn how to put together everything you have learned so far and produce well-formed XML documents. You will be introduced to some basic parsing tools and then learn how to check and correct your XML documents.

•  On Day 6, you will learn all about DTDs, their subsets, and how they are used to check XML documents for validity.

•  On Day 7, you’ll delve even further into the treacherous waters of DTD development and learn some of the major tricks of the trade that open the doors to advanced XML document construction.

Week two takes you into the “power” side of XML authoring:

•  On Day 8, you will learn about entities and notations, and how to import external objects such as binary code and graphics files into your XML documents.

•  On Day 9, you’ll arrive at the next major milestone. You will be introduced to a couple of the leading XML parsers, and you’ll learn how to validate your XML documents and recognize and correct some of the most common errors.

•  On Day 10, you will discover the power of XML’s linking mechanisms. Using practical examples, you will learn how you can use XML links to go far beyond HTML’s humble features.

•  On Day 11, you will continue to explore XML’s linking mechanisms. You will learn how you can link to ranges, groups, and indirect blocks of data inside both XML and non-XML data.

•  On Day 12, with much of the theory already in your grasp, you will learn how you can actually display the XML code you’ve written in Microsoft’s Internet Explorer 5.

•  On Day 13, you will continue the hands-on work of Day 12 by learning how to display the XML code you’ve written in Mozilla, Netscape’s Open Source testbed for the development of future versions of its Web browser software.

•  On Day 14, you will learn the basics of XML document processing. You will be introduced to the principles of tree-based and event-driven processing and learn when and how to apply them.

Week three takes you beyond XML authoring and teaches you how to process XML and HTML code.

•  On Day 15, you will learn more about event-driven processing. You will learn how to download, install, and use two of the leading tools: Omnimark and SAX.

•  On Day 16, going several steps further, you will learn how to use the Document Object Model (DOM) to gain programmatic access to everything inside an XML document.

•  On Day 17, you will temporarily turn your back on XML code as a means of coding documents and examine how it’s used to code data. You will learn why a DTD sometimes isn’t enough, and you’ll be introduced to some of the most important XML schemas.

•  On Day 18, you will return to using XML for documents and explore how the Cascading Style Sheet language (CSS), originally intended for use with HTML, can be used just as easily with XML code. With the aid of practical examples, you will learn how you can legitimately use CSS code to render XML code. If that doesn’t work, you’ll also learn a few tricks to fool the browser into doing what you want it to do.

•  On Day 19, you will learn the basics of DSSSL, the style language for rendering and processing SGML code. You will learn how easy it can be to use DSSSL to transform not just SGML code, but also XML and HTML code. With the help of numerous examples, you will also learn how to convert XML code into HTML and RTF, and how to convert HTML into RTF or even FrameMaker MIF using jade.

•  On Day 20, you will be briefly introduced to earlier versions of the XML style languages before concentrating on XSL. Using the very latest XSL tools, you will learn how to create your own XSL style code and display the results.

•  On Day 21, you will learn the basics of MathML, the mathematics application of XML, as well as the various initiatives to describe graphics in XML. (No book on XML would be complete without some mention of its applications.) Using practical examples, you will be introduced to VML and see how you can already use it in Microsoft Internet Explorer, versions 4 and 5. Finally, you will take a peek at some of the new developments that are just around the corner, such as Office 2000, CSS behaviors, and Microsoft’s Chrome.

The end of each chapter offers common questions and answers about that day’s subject matter and some simple exercises for you to try yourself. At the end of the book, you will find a comprehensive glossary and an extensive appendix of XML resources containing pointers to most of the software packages available, whether mentioned in this book or not, and pointers to the most important sources of further information.

This Book’s Special Features

This book contains some special features to help you on your way to mastering XML.

Tips provide useful shortcuts and techniques for working with XML. Notes provide special details that enhance the explanations of XML concepts or draw your attention to important points that are not immediately part of the subject being discussed. Warnings highlight points that will help you avoid potential problems.

Numerous sample XML, DSSSL, XSL, HTML, and CSS code fragments illustrate some of the features and concepts of XML so that you can apply them in your own document. Where possible, each code fragment’s discussion is divided into three components: the code fragment itself, the output generated by it, and a line-by-line analysis of how the code fragment works. These components are indicated by special icons.

Each day ends with a Q&A section containing answers to common questions relating to that day’s material. There is also a set of exercises at the end of each day. We recommend that you attempt each exercise. You will learn far more from doing yourself than just seeing what others have done. Most of the exercises do not have any one answer, and the answers would often be very long. As a result, most chapters don’t actually provide answers, but the method for finding the best solution will have been covered in the chapter itself.