Disadvantages of Using DOM

Disadvantages of Using DOM

Although DOM is a W3C specification with support for a variety of programming languages, it’s not necessarily the best solution for all problems. One of the big issues is that DOM can be memory intensive. As mentioned earlier, when an XML document is loaded, the entire document is read in at once. A large document will require a large amount of memory to represent it. Other parsing methods, such as SAX, don’t read in the entire document, so they are better in terms of memory efficiency for some applications.

Some have argued that the DOM API is too complex. Although this is somewhat subjec-tive, it is true that DOM is not practical for small devices such as PDAs and cellular phones. With the rapid proliferation of these devices and demand for greater functional-ity, XML will very likely play a role in this market. In these cases, DOM as specified by the W3C might not be the best way to go. Fortunately, there are smaller, simpler APIs for XML manipulation that follow the spirit, if not the letter, of DOM. Some of these alter-native APIs are discussed later in this chapter.

Of course, everything is relative. If you want to write a quick-and-dirty program without the need for a lot of functionality, you might not require a sophisticated API at all. If all you want to do is generate a relatively simple XML document, you can always write out XML directly and avoid DOM entirely. However, as any veteran programmer knows, that quick-and-dirty code you wrote the midnight before the demo somehow always finds its way into production and becomes a maintenance nightmare!