Bancos de dados ativos como suporte a restrições topologicas em sistemas de informação geografica

Claudia Maria Bauzer MedeirosDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Ciencia da ComputaçãoResumo: Esta dissertação trata da utilização de sistemas ativos no contexto de aplicações geográficas. Os resultados aqui apresentados estendem o paradigma de SGBD ativos com o objetivo de solucionar o problema de manutenção de relacionamentos espaciais (topológicos) na presença de atualizações. A solução apresentada para este problema está dividida em três etapas: i) especificação da restrição topo lógica; ii) transformação da restrição em regras; e iii) manutenção automática da restrição, com base nas regras geradas. Esta abordagem foi utilizada no desenvolvimento de um protótipo de sistema ativo que incorpora um modelo geográfico OO, eliminando o problema da impedância existente entre Sistemas de Informação Geográfica (SIG) e sistemas de regras. As principais contribuições deste trabalho são um estudo detalhado sobre relacionamentos topológicos binários; uma proposta integrada para o problema de manutenção desses relacionamentos; e a definição de algoritmos para a verificação de integridade topológica, implementados no protótipo.Abstract: This dissertation concerns the use of active databases in geographic applications. The results presented here extend the active database systems paradigm to solve the problem of maintaining spatial (topological) constraints. The solution for this problem is divided in three steps: i) topological constraint specification; ii) translation of the constraint into roles; and iii) automatic constraint maintenance, using the generated rules. This approach was used in the development of an active system prototype that incorporates an object-oriented geographic model, thus removing the gap between Geographic Information Systems (GIS) and role systems. The main contributions presented are a detailed study about binary topological relationships; an integrated proposal for the problem of maintaining these relationships; and the definition of algorithms to verify the topological integrity (these algorithms are incorporated in the prototype).MestradoMestre em Ciência da Computaçã

The inference problem in multilevel secure databases

Conventional access control models, such as role-based access control, protect sensitive data from unauthorized disclosure via direct accesses, however, they fail to prevent unauthorized disclosure happening through indirect accesses. Indirect data disclosure via inference channels occurs when sensitive information can be inferred from nonsensitive data and metadata, which is also known as “the inference problem”. This problem has draw n much attention from researcher in the database community due to its great compromise of data security. It has been studied under four settings according to where it occurs. They are statistical databases, multilevel secure databases, data mining, and web-based applications. This thesis investigates previous efforts dedicated to inference problems in multilevel secure databases, and presents the latest findings of our research on this problem. Our contribution includes two methods. One is a dynamic control over this problem, which designs a set of accessing key distribution schemes to remove inference after all inference channels in the database has been identified. The other combines rough sets and entropies to form a computational solution to detect and remove inferences, which for the first time provides an integrated solution to the inference problem. Comparison with previous work has also been done, and we have proved both of them are effective and easy to implement. Since the inference problem is described as a problem of detecting and removing inference channels, this thesis contains two main parts: inference detecting techniques and inference removing techniques. In both two aspects, some techniques are selectively but extensively examined

Implementing Integrity Control In Active Data Bases

This article presents a system for maintaining static integrity constraints in data bases that uses the active data base paradigm. This system has been added to an active version of the O2 object-oriented data base system, and it is fully functional. Constraints, specified by the user in a fist-order logic language, are transformed into production rules, which are stored in the data base. These rules are used to maintain the corresponding set of constraints for all applications that use the data base. We extend previous work on constraint maintenance in two ways: our system can be used as a constraint maintenance layer on top of object-oriented, relational, and nested relational data bases, and for object-oriented systems, we provide constraint support not only in the case of object composition, but also consider inheritance and methods. © 1994.273171181Adiba, Collet, Coupaye, Habraken, Machado, Martin, Roncancio, Trigger Systems: Different Approaches (1993) Technical Report Aristote-SUR007, , Laboratoire de Génie Informatique, IMAG, Grenoble, FranceAndrade, Manutenção de Restrições de Integridade em Bancos de Dados Orientados a Objetos (1992) Master's Thesis, , Department of Computer Science, UNICAMP, CampinasAiken, Widom, Hellerstein, Behavior of Database Production Rules: Termination, Confluence and Observable Determinism (1992) Technical Report FJ8562, , IBM, AlmadenBuchmann, Branding, Kudrass, Zimmermann, REACH—A REal-Time, ACtive and Heterogeneous Mediator System (1992) IEEE Bull. 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