ubQL, a Language for Programming Distributed Query Systems
		   (Extended Abstract)
	    Arnaud Sahuguet and Val Tannen


ubQL is a distributed query language for programming large-scale
distributed query systems such as resource sharing systems. The
language is obtained by adding a small set of mobile process primitives
(communication channels, migration operators, etc.) on top of any
traditional query language. Queries are encapsulated into processes
and can migrate between sites thus enabling cooperation.  An important
methodological device is the separation of the installation
(including migration) of query processes from the distributed
execution of the queries.

In this paper, we give an overview of ubQL, show how to encode
widely used distributed query patterns such as chaining,
recruiting, query/data/hybrid shipping, etc., and evaluate some
language-based rewrite strategies for the installation of ubQL
queries that use only partial and distributed knowledge of
execution costs.