Chapter 3. Advanced Operations with Axiom

Axiom is tightly integrated with StAX and the getXMLStreamReader() and getXMLStreamReaderWithoutCaching() methods in the OMElement provides a XMLStreamReader object. This XMLStreamReader instance has a special capability of switching between the underlying stream and the Axiom object tree if the cache setting is off. However, this functionality is completely transparent to the user. This is further explained in the following paragraphs.

Axiom has the concept of caching, and the Axiom tree is the actual cache of the events fired. However, the requester can choose to get the pull events from the underlying stream rather than the Axiom tree. This can be achieved by getting the pull parser with the cache off. If the pull parser was obtained without switching off cache, the new events fired will be cached and the tree updated. This returned pull parser will switch between the object structure and the stream underneath, and the users need not worry about the differences caused by the switching. The exact pull stream the original document would have provided would be produced even if the Axiom tree was fully or partially built. The getXMLStreamReaderWithoutCaching() method is very useful when the events need to be handled in a pull based manner without any intermediate models. This makes such operations faster and efficient.

	For consistency reasons once the cache is switched off it cannot be switched on again.