21 Storing Feed (Web design) Data In this chapter we
21 Storing Feed Data In this chapter we extend and develop the ideas and techniques discussed regarding the modeling of feeds with an emphasis on building practical systems. In this chapter, you learn about: . Simple DOM-based XML storage . Flat relational database storage . RDF-modeled data storage There is another popular set of techniques for storing feed data based around native XML databases and the XPath standard for addressing their contents. These techniques tend to depend on the implementation details of the database being used, so coverage will be left to the practical example in Chapter 26. The Document Object Model In the previous chapter, we treated the modeling of a feed as a document rather dismissively. But the drawbacks we described didn t have anything to do with document modeling, but with treating the feed as an integral, fixed document. The Document Object Model (DOM) is a standard interface for working with documents that allows them to be created from or broken down into component parts. The DOM specifications can be found at www.w3.org/DOM/. DOM treats documents as tree structures comprising a root, branch, and leaf elements. DOM treats elements, attributes, and text as elements in a parent-child structure, and in a typical XML document the hierarchy is fairly clear, as you can see in Figure 21-1.
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