Python & XML

Understanding SAX

The first job of using SAX is to design and implement a handler that works with your specific XML documents. When dealing with a large project or working with a vast catalogue of valid documents, it may make sense to implement a few comprehensive handlers to deal with multiple document types. However, for smaller projects, it may be more desirable to implement handlers for each specific document type that you encounter. As you start to build more complex applications, you will see that the things you’re attempting to do with the XML as well as the XML documents themselves can drive the way you develop your document handlers. Often, the SAX methods that you implement extract data from the event stream, which you can then hand off to another application (such as a database). Or you might want to apply intelligent business logic to it. It’s likely that the task will drive your development strategy.

In all practical use, SAX is a callback-based API in which you implement handler objects to process XML. You pass a reference to your SAX handler objects to a SAX-capable parser (or driver; we’ll use “parser” to refer to either). When parsing begins, the parser calls the methods on your handler objects and allows you to process the XML, so that you can do something useful with it in your applications and distributed systems.

SAX is an excellent stream-based API. It allows for faster processing of documents, as well as handling of documents that are simply too large to load ...