This article is excerpted from Managing Enterprise Content, by Ann Rockley (2002 New Riders Publishing, ISBN 0735713065).
You can implement a unified content strategy without XML, using traditional authoring tools, but XML provides you with the ability to do a whole lot more. There are disadvantages to XML, notably that it is a new technology that brings issues in dealing with the learning curve, the complexity, and the implementation. However, the disadvantages are outweighed by the advantages. The characteristics of XML that best support reuse are:
- Structured content
- Separation of content and format
- Built-in metadata
- Database orientation
- XSL style sheets
These are described in more detail in the following sections.
XML and structured content
Authors typically have a high-level understanding of the concept of structured content. For example, they understand that books have front matter, body chapters, and back matter. Authors may also recognize repeatable structures at a lower level. Chapters have titles, overviews, sections containing the "meat" of the chapter, and a summary. Some authors can even describe the structure in individual sections, for example, a procedure. However, when you examine similar information products, you find that structures are not consistent from product to product. Structures will vary from author to author, from department to department, from division to division. Even information written by a single author will vary over time. This is a big problem for reuse.
In XML, structure can be defined in a Document Type Definition (DTD) or Schema1. A DTD is quite specific; it defines all the elements (XML tags) that can be used in a document. It also defines the relationship of those elements to other elements. You can specify the hierarchy of elements ("a chapter contains..."), the order of elements, or even the number of elements.
A DTD can be incredibly valuable for the writing process. Many authors take as much time figuring out the structure they need to write to as they do actually crafting the information. Does my presentation need an overview? Does my procedure have an introduction? Do I need to include a title for a graphic? With a DTD, you can mandate the structure that is required. This consistency is also very valuable for the information's users. Consistency leads to predictability. Users learn where information is to be found and can automatically navigate to it, finding what they need quickly and efficiently. In addition, a DTD provides a powerful map for systematic reuse and personalization. When content is systematically reused, the content management system must identify what content can be reused where. The DTD specifies this information. Personalization also requires a map and set of rules to define what information should be provided and in what order. The DTD provides this information.
For structural consistency, having a defined structure in a DTD is half of the solution. The other half is provided by specialized editing tools (called validating editors) that can read a DTD and enforce the structural rules defined in it. By providing authors with a validating editor and a DTD, you can ensure that all your information products are structurally consistent.