The Unified Service Query Language Technical Report

This report presents the specification of the Unified Service Query Language (USQL), which is aimed at supporting the discovery of heterogeneous Web, Peer-to-Peer, and Grid services. At the conceptual level, USQL establishes an abstract and service type-independent viewpoint of the service properties, which are constrained by service requesters through their search criteria. At the grounding level, the language provides an XML-based syntax for the formulation of service discovery requests and responses. Overall, USQL is characterized by a high-level of abstraction, which ensures compatibility with existing service description and discovery standards, and extensibility, which allows for easy accommodation of additional service properties and/or support for emerging service technologies.