Retrieving instance data from server side

Hi all,

I am on a team developing advanced forms which are intended to give dynamic assistance to the user when filling them. For the field the user is filling up, they should show information of how often each option or value has been chosen in previosly filled up forms regarding to the already filled up values. For this purpose,  on each change of the fields we have to submit the instance which contains the already filled up values and context information needed for calculating the probability of each option or value to be chosen next. This is a big chunk of data and has to be  very often sent and read into XML for processing it with Java processor.

After reading and searching in the Orbeon docs and experimenting with orbeon when changing fields, I suspect that the server keeps an updated copy of each instance for each session and updates it via AJAX every time a change hapens. Is it possible to retrieve directly that instance data from session or eXist passing just a reference instead of submitting the whole instance data chunk?

Thanks a lot for the help and sorry if any of what I said is just nonsense.

Regards,

Manu.