DTMDocumentImpl was intended to be a port of the "ultra-compressed" first-draft version of DTM to the Xalan 2.0 environment. As far as I know, we never finished porting it; the code is in unstable state. If someone can invest the cycles to try to bring it up to full operation, it'd be an interesting space/performance comparison point.
Note that DTM has no ability to "modify the value" of a node. It's strictly a write-once-read-many API. Theoretically, changing the content of an existing attribute or text node would not be hard to add... but practically, that has ugly interactions with issues like namespace lookup and ID nodes and such. I'd hesitate to go that route. Alternatively: If your concern is the overhead of DTM on top of the DOM (the DOM2DTM layer) rather than the size of your source DOM per se, I just checked in a VERY early draft of a "thinner" adapter (DOM2DTM2) over on the XSLT20 branch. It's specifically intended to avoid replicating so much of the DOM structure, and to better tolerate repeatedly running stylesheets over the same source DOM. In its current form it is rather slow, but I hope to improve that. ______________________________________ Joe Kesselman / IBM Research
