Executive Summary

It's important to differentiate between the narrowly defined XML specification and the broadly defined XML paradigm. The XML specification itself has two parts : one for XML documents and one for XML DTDs. The document portion governs the use of tagged markup to indicate the meaning of data. The DTD portion governs how to describe the allowable structure for a class of XML documents. This chapter focuses on the narrow XML specification.

Often, however, the term XML is used to refer to a broader Internet software paradigm in which XML documents serve as the foundation. This paradigm encompasses a wide variety of standards that both enhance the document processing platform and add domain-specific capabilities. Chapter 3 introduces some of the important platform standards, and Chapter 4 focuses on the platform and domain standards related to sending XML business messages over the Internet.

Figure 2-1 shows how XML supports this larger paradigm. As you can see, the paradigm is somewhat modular, where you can use each part for a particular application. Some applications may use only XML documents, while others may include XML DTDs. Still others may take advantage of processing standards or messaging standards.

Figure 2-1. XML Supports a Larger Paradigm

Because the XML specification is a foundation for the entire paradigm, understanding the basics of XML syntax is fundamental to comprehending the power of the paradigm. The process of learning these mechanisms will also help you develop an intuition for where XML can be the most beneficial. Although you probably won't create many XML documents, a command of the syntax improves your ability to collaborate effectively with developers.