69 research outputs found
SMOQE: A System for Providing Secure Access to XML
No full textXML views have been widely used to enforce access control, support dataintegration, and speed up query answering. In many applications, e.g., XMLsecurity enforcement, it is prohibitively expensive to materialize and maintaina large number of views. Therefore, views are necessarily virtual. An immediate question then is how to answer queries on XML virtual views. A common approach is to rewrite a query on the view to an equivalent one on the underlying document, and evaluate the rewritten query. This is the approach used in the Secure MOdular Query Engine (SMOQE). The demo presents SMOQE, the first system to provide efficient support for answering queries over virtual and possibly recursively defined XML views. We demonstrate a set of novel techniques for the specification of views, therewriting, evaluation and optimization of XML queries. Moreover, we provideinsights into the internals of the engine by a set of visual tools
Data sharing and querying for peer-to-peer data management systems
No full textAbstract. In this work, we investigate mechanisms to support data sharing and querying in a peer-to-peer data management system, that is, a peer-to-peer system where each peer manages its own data. To support data sharing, we propose the use of mapping tables which list pairs of corresponding data values that reside in different peers. Our work illustrates how automated tools can help manage the tables between multiple peers by inferring new tables from existing ones and by checking their consistency. In terms of querying, we propose a framework in which users pose queries only with respect to their local peer. Then, we provide a rewriting mechanism that uses mapping tables to translate a locally expressed query to a set of queries over the acquainted peers.
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