Control in XML PDMS Query Answering

Peer data management system (PDMS) is a decentralized system, in which each peer is autonomous and has its own schema and database. With the help of pairwise schema mapping built between any two relevant peers, a query at one peer can be rewritten and broadcast to the whole PDMS. Then answers from multiple peers are returned to the querying peer. In our thesis, we exploit the access control issues in the query-answering process of the XML PDMS. We propose a formal syntax for access control policy (ACP) to specify the fine-grained access control privileges on peers’ local XML database. We also design several query-answering algorithms that aim to handle access control in the PDMS, define the algorithm properties of Information Leakage Free and Completeness, and analyze every designed query-answering algorithm on the two properties. A comprehensive cost model, which consists of the major tasks and primitive operations, is proposed by us to assess the query-answering algorithms. We implement the designed query-answering algorithms, compare their running time, and test the scalability in different facets.