Save direct to xml?

I have the dhtmlxTree Pro and several others. I built this awesome program in minutes using the tree and tabbar.

We use the tree to display a list of things that need to be accomplished. When you click a checkbox, the item is complete. Saving to cookie is fine for a single user but what if others need to see what someone else updated. A database is great but some clients will have php and some asp, some will have mySQL and others SQLserver.

Bottom line, I am loading data to the tree from an xml file in the /common/ folder. Can I save back to this xml file?

It is possible to serialize tree to the xml string using serializeTree method:

tree.setSerializationLevel(false,true);
var xmlString = tree.serializeTree();

To update xml file you need to use some server-side script.