xml-dev - Build the delta from two xml documents

["Komoll, Oliver" <O.Komoll@klopotek.de>]

Hi,
i look for a solution to solve the following problem:

i want to build a xml-based interface to pass my data to a client(Web etc.)
and i dont know in which way the client manipulates the data and what in the
xml-document was changed, inserted or deleted.
What i have is the original-document and the changed-document (both based on
the same DTD). How can i determine the delta from the two documents ? 
Please dont say "alphaworks", cause the license is only for 90 days and
there solutions (diff/merge, xmltreediff) couldt not be sold :-(

any free or commercial suggestion for java or xpath ???


TIA

Oliver