1. INTRODUCTION
With the advent of the Web, data management has moved
away from the traditional framework to match the variety
of information available on the Web [20]. Nowadays, web
documents are often used for storing data over the inter-
net, whilst XQuery language has become the standard for
retrieving such documents. The main architecture of data
integration systems is based on the mediator approach [23].
A Multi-data source Fusion Language (MFL) has been pro-
posed recently in [15]. This language provides a °exible
integration of data sources on dynamic environments which
is the web case.