If I have a large XML document, which I don't want to load entirely into memory, and some configurable value like an XPath statement or othe format that identifies a path to an element in the xml, is it possible to read the xml from a stream node by node until I find the location I am looking for? 

We need to build facilities to pull out a value from xml without knowing the schema. All we have is the xml document and an xpath statement. We could probably revise to use something other than xpath, but we really want to avoid loading up the whole document because we need to process in realtime, and the xml could be fairly large, and the volume could get high.