Computing Capabilities of Mediators 

	Ramana Yerneni, Chen Li, Hector Garcia-Molina, Jeffrey Ullman
	Department of Computer Science, Stanford University 
	yerneni,chenli,hector,ullmang@cs.stanford.edu

			Abstract 

  Existing data-integration systems based on the mediation architecture e
  mploy a variety of mechanisms to describe the query-processing
  capabilities of s ources. However, these systems do not compute the
  capabilities of the mediators based on the capabilities of the sources
  they integrate. In this paper, we propo se a framework to capture a rich
  variety of query-processing capabilities of dat a sources and
  mediators. We present algorithms to compute the set of supported q
  ueries of a mediator, based on the capability limitations of its
  sources. Our al gorithms take into consideration a variety of
  query-processing techniques employed by mediators to enhance the set of
  supported queries.