The XMLServer presents an XML view of a relational database which is defined by an XML schema with all the necessary information contained in the appinfo elements of the schema. It serves the constructed XML to a browser, Java or Mathematica. You may get a record by key and the next or previous one.
There are currently a large number of products dedicated to this end (see Bourret ). What distinguishes this product is it's ability to construct arbitrarily complex trees.XMLServer Beta Version 1, and freely use and distribute it.