Semantics of Database Transformations

Database transformations arise in many different settings including database integration, evolution of database systems, and implementing user views and data entry tools. This paper surveys approaches that have been taken to problems in these settings, assesses their strengths and weaknesses, and develops require ments on a formal model for specifying and implementing database transformations. We also consider the problem of insuring the correctness of database transformations. In particular, we demonstrate that the usefulness of correctness conditions such as information preservation is hindered by the interactions of transformations and database constraints, and the limited expressive power of established database constraint languages. We conclude that more general notions of correctness are required, and that there is a need for a uniform formalism for expressing both database transformations and constraints, and reasoning about their interactions, Finally we introduce WOL, a declarative language for specifying and implementing database transformations and constraints. We briefly describe the WOL language and its semantics, and argue that it addresses many of the requirements on a formalism for dealing with general database transformations

Reinvestigation of aminoacyl-TRNA synthetase core complex by affinity purification-mass spectrometry reveals TARSL2 as a potential member of the complex

10.1371/journal.pone.0081734PLoS ONE812-POLN

A Model for Evolution of Services in Distributed Systems

Large software systems are never static. They exist in an environment that is subject to constant changes in both functionality and technology. This is particularly a problem for large-scale distributed systems, where different components may be subject to different, divergent, pressures. This paper describes work carried out on an RM-ODP-based model for evolution of distributed application services under such conditions. It examines problems which may occur when services evolve to their new versions without corresponding evolution in their clients and presents a mechanism to preserve such old services as are still needed. The model uses the idea of a `mapping' to provide the impression of old services using their new versions. A prototype of the model has been implemented on the ANSAware platform, giving an example of how the model can be applied in a working distributed environment

Programming by Formal Refinement of Conceptual Design". IEEE- Data Engineering, (September 1989).

Programming Languages, Oregon (June 1989), pp. 203-212