SSQL: a set based query language for distributed repository

: Nowadays, information plays a fundamental role inside every kind of activity: its ever-growing importance does not regard only computer science but also concerns a huge number of everyday activities. Information is useful only if it is structured and manageable: this is perhaps the main goal of all the information systems. This paper describes an original alternative to the same old graphical forms used to query a repository: a set based logic query language. The query technique proposed is based on a declarative language that emphasises the set as main data type. In particular, sets are a natural and intuitive model for structured data collections. The query language produced, called SubSet Query Language (SSQL), expands the functionalities of the starting language and introduces the capability to access an external repository. A class of new built-in predicates has been added to the starting language and the compilation and the execution environment have been adapted to the new functionalities introduced. The SSQL paradigm has been integrated inside a distributed software artefact library and use statistics are being gathered. An initial evaluation of the SSQL paradigm, based on the experience so far acquired, shows that, in the phase of an initial effort to experience the methodology, great efficiency and flexibility can be obtained.