Stylesheet Language Transformation (XSLT). You’ll also see how to use XSQL to create graphics on the fly and to render Portable Document Format (PDF) documents based on dynamic data. All the while, the easiest cases require no Java coding at all. You only have to use Java coding for the more complex interactions with the database. This chapter serves as a general overview to XSQL, as well as the foundation tech- nologies. The first topic covered is an examination of what XSQL solves. This includes some short code examples that illustrate how powerful XSQL can be. The next discus- sion explores how XSQL relates to other Oracle technologies. You don’t have to use XSQL exclusively with Oracle, but XSQL makes a great combination. The chapter ends with some in-depth exploration of XML. XSQL and XSLT are derived from XML, so you need to have a good understanding of XML before diving in. What XSQL Solves Before trying to learn any new technology, it is worthwhile to thoroughly understand the  problems  that  the  technology  solves.  In  the  previous  paragraphs,  you  were promised that XSQL brings technologies together. In this section, you’ll see, at a high level, how XSQL delivers on that promise. More important, however, you’ll see why the integration of the various technologies is a problem in the first place. The  first  step  is  to  understand  what  the  key  problems  are  with  Web  application development. The marriage of the Web with enterprise applications has its problem spots, just like any marriage. As you’ll see, XSQL greatly simplifies a key component of the relationship: database access. This leads to the next discussion: How does the data- base fit into modern Web application development? As you’ll see throughout the book, the Oracle database is great for storing not only relational information, but XML infor- mation, also. XML, in turn, offers a lot of solutions to the fundamental problems of Web application development. Because XSQL is fundamentally XML based, it’s important to understand how XML provides these solutions. Always nearby XSQL is XSLT. XSLT allows you to transform XML into . . . well, almost anything. In a world of so much technology, the problem of transforming from one data format to another comes up regularly. XSLT solves this problem, and will start the examination in this section. The section ends with an examination of how XSQL bridges the gap between all of these technologies. The Problems of Web Application Development This chapter is all about perspective, and nothing gives a better perspective than his- tory. So to begin our discussion of the current state of Web application development, it’s worthwhile to first consider the history of the Web itself. In the beginning—way back in 1990-—there were just HTML, Uniform Resource Locators (URLs), and HTTP. The real beauty of the system was hyperlinks. Tim Berners-Lee was proposing that you could link documents together—get this—across a network! His paper, “Information Management, A Proposal” from 1990 says it best: Imagine,  then,  the  references  in  this  document,  all  being  associated  with  the  network address of the thing to which they referred, so that while reading this document you could skip to them with a click of the mouse. 2 Chapter 1 271209 Ch01.F  12/9/02  2:00 PM  Page 2