Defining XML Using Alternate Schema Representations
IN THIS CHAPTER
• A Brief Review of XML Schemas
• Dead Formats: XDR, DSD, and DCD
• Schema for Object-Oriented XML (SOX)
• RELAX NG Schema
Within the XML world, the XML Schema Definition Language is emerging as a sup-ported standard for creating XML Schemas since its final recommendation given by the W3C in May of 2001. However, it is not the only supported standard defining XML schemas. Over time, while the W3C was busy refining its formal schema definition lan-guage, the rest of the world created its own. For every markup language, there is proba-bly one schema definition language. Depending on the technologies you’re used to incorporating within your applications, you may be more familiar with some of these alternate schema definition languages than others.
These alternate schema definition languages cover everything from being subsets of other schema definition languages to serving a specialized purpose, as is the case with the Schema for Object-Oriented XML (SOX) schema definition language, which is geared for, you guessed it, object-oriented XML documents. We’ll take the rest of the chapter to discuss these other formats, briefly, which include the following:
XML Data Reduced (XDR) schemas
Document Structure Definition (DSD) schemas
Document Content Description (DCD) schemas
Schema for Object-Oriented XML (SOX)
A chapter could be devoted to each of these alternate schema formats. However, this chapter is meant to give you a brief overview of some of the other schema formats avail-able. For each format, a URL is listed where you can find more information if needed.