Dynamic description logic model for data integration

Abstract

Data integration is the issue of retrieving and combining data residing at distributed and heterogeneous sources, and of providing users with transparent access without being aware of the details of the sources. Data integration is a very important issue because it deals with data infrastructure issues of coordinated computing systems. Despite its importance, the following key challenges make data integration one of the longest standing problems around: 1) how to solve the system heterogeneity; 2) how to build a global model; 3) how to process queries automatically and correctly; and 4) how to solve semantic heterogeneity. This paper presents an extended dynamic description logic language to describe systems with dynamic actions. By this language, a universal and unified model for relational database systems and a model for data integration are presented. This paper presents a universal and unified description logic model for relational databases. The model is universal because any relational database system can be automatically transformed to the model; it is unified because it integrates three essential components of relational databases together: description logic knowledge bases modeling the relational data, atomic modalities modeling the atomic relational operations, and combined modalities modeling the combined relational operations-queries. Furthermore, a description logic model for data integration is proposed which contains four layers of ontologies. Based on the model, a solution for each key challenge is proposed: a universal model eliminates system heterogeneity; a novel global model including three ontologies is proposed with some important benefits; a query process mechanism is provided by which user queries can be decomposed to queries over the sources; and for solving the semantic heterogeneity, this paper provides a framework under which semantic relations can be expressed and inferred. In summary, this paper presents a dynamic knowledge base framework by an extended description logic language. Under the framework, databases and data integration systems are modeled, the query processing problem is converted into a semantic-preserving rewriting problem, and many other issues of data integration can be formally studied. © 2008 Higher Education Press and Springer-Verlag GmbH.