Java EE (Java Enterprise Edition) General Discussion

Hello

I'm creating a "SurveyEngine" application that will use a XML document defining the questions and storing the answers of the users. There is part of my webApp that must:
1-parse the XML file (i am ok till there)
2-append a XML child node (.. it should not be too hard, but if you have sample codes, please send)
3-translate the modified document object back to a string to overwrite the file

I need help mostly for the 3th step. I looked in the java API in the packages dom, sax, etc... and I didnt find anything. Could someone tell me which package.class I must use? If you know that such a class does not exist in the java API, but that you already defined a class to handle generic_node-to-string translation, I would be very grateful if you could send me your sources.

Thanks in advance,
Alexandre Bouchard