Great! How Do I Get Started?
The four essential steps to building an XML-based system or application are the following:
Requirements gathering (described in Chapter 3)
Abstract data modeling (Chapter 4)
-Application design, including DTD (document type definition) and schema design (Chapters 5 and 6)
-Implementation (Chapters 8 and 9)
If you follow this plan, you won't write one line of application code until step 4. Building an XML-based application is writing software and requires the same rigorous approach.
The four steps don't mention platform at all. Are we implementing on UNIX or Windows NT? Oracle or MySql? Java or Perl? XML and database design free you from platform-dependent approaches to data storage and manipulation, so take advantage of that freedom, and don't even choose a platform until at least midway through step 2. Base that platform decision on what features it includes to get you closer to your goalbuilt-in features that fit into your business requirementshow easy the platform is to support ongoing operations (operational considerations).
You can incorporate the same methodology when integrating XML into an existing RDBMS-based application. Throughout the following chapters, we'll examine how to build an XML-based application. You'll learn how to collect your requirements, build an abstract data model around these requirements, and then build an XML DTD and a relational schema around this data model. We'll get into implementation only in the abstract, describing how your system must interact with the DTD and schema.