multilevelsecure database systems are the systems in which security classifications are assigned from the relations to data elements. Due to security requirements of databases, the concurrency control mechanisms for ...
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ISBN:
(纸本)9781479929955
multilevelsecure database systems are the systems in which security classifications are assigned from the relations to data elements. Due to security requirements of databases, the concurrency control mechanisms for such databases are different than the concurrency control mechanisms in traditional databases. In this paper, we present a new algorithm for concurrency control that is shown to be starvation-free to some extent.
The partitioned synchronization rule is a technique for proving the correctness of concurrency control algorithms. Prior work has shown the applicability of the partitioned synchronization rule to hierarchically decom...
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The partitioned synchronization rule is a technique for proving the correctness of concurrency control algorithms. Prior work has shown the applicability of the partitioned synchronization rule to hierarchically decomposed databases whose structure is restricted to semitrees. The principal contribution of this paper is a demonstration that the partitioned synchronization rule also applies to more general structures than semitrees, specifically, to any planar extendible partial order, a partial order which when extended with a least and a greatest element still remains planar. To demonstrate utility, the paper presents two applications of the partitioned synchronization rule. The first application shows correctness of a component-based timestamp generation algorithm suitable for implementing a timestamp ordering concurrency control algorithm. The second application shows correctness of a snapshot algorithm for concurrency control in a replicated multilevelsecure database;we choose this application to highlight that hierarchically decomposed databases and multilevel secure databases are structurally Similar. In both cases, the correctness proofs via the partitioned synchronization rule are substantially simpler than corresponding direct proofs.
This paper proposes a taxonomy for secure object-oriented databases in order to clarify the issues in modeling and implementing such databases. It also indicates some implications of the various choices one may make w...
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This paper proposes a taxonomy for secure object-oriented databases in order to clarify the issues in modeling and implementing such databases. It also indicates some implications of the various choices one may make when designing such a database. Most secure database models have been designed for relational databases. The object-oriented database model is more complex than the relational model, and object-orientation is not based on a formal (mathematical) model like the relational model. For these reasons, models for secure object-oriented databases are more complex than their relational counterparts. Furthermore, since views of the object-oriented model differ, each security model has to make some assumptions about the object-oriented model used for its particular database. A number of models for secure object-oriented databases have been proposed. These models differ in many respects, because they focus on different aspects of the security problem, or because they make different assumptions about what constitutes a secure database or because they make different assumptions about the object-oriented model. The taxonomy proposed in this paper may be used to compare the various models: Models that focus on specific issues may be positioned in the broader context with the aid of the taxonomy. The taxonomy also identifies the major aspects where security models may differ and indicates some alternatives available to the system designer for each such design choice. We show some implications of using specific alternatives. Since differences between models for secure object-oriented databases are often subtle, a formal notation is necessary for a proper comparison. Such a formal notation also facilitates the formal derivation of restrictions that apply under specific conditions. The formal approach also gives a clear indication about the assumptions made by us-given as axioms-and the consequences of those assumptions (and of design choices made by the model designer)-gi
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