XML in a Nutshell, 3rd Edition

Combining Approaches

While text, events, trees, and transformations may seem very different, it isn’t unusual to combine them. Most parsers that produce DOM trees also offer the option of SAX events, and there are a number of tools that can create DOM trees from SAX events or vice versa. Some tools that accept and generate SAX events actually build internal trees—many XSLT processors operate this way, using optimized internal models for their trees rather than the generic DOM. XSLT processors themselves often accept either SAX events or DOM trees as input and can produce these models (or text) for their output.

Most programmers who want direct access to XML documents start with DOM trees, which are easier to figure out initially. If they have problems that are better solved in event-based environments, they can either rewrite their code for events—it’s a big change—or mix and match event processing with tree processing.