Automatic Mapping Generation and Adaptation for XML data sources
Xiaohui Xue · 2006
The integration of information provided by multiple heterogeneous data sources is required by many modern information systems. In this context, the applications' needs are described by a target schema and the way instances of the target schema are derived from the data sources is expressed through mappings. A mapping describes the transformation and the integration of the source instances to conform to the target structure. In this thesis, we address the problem of mapping generation for multiple XML data sources and the automatic adaptation of these mappings when the target schema or the source schemas evolve. We propose a generation approach that first decomposes the target schema into subtrees, then defines mappings, called partial mappings, for each of these subtrees, and finally combines these partial mappings to generate the mappings for the whole target schema. The result of our approach is a set of mappings having different semantics. If the information required in the target schema can not be provided by the sources, then no mapping can be generated; in this case, we propose to relax some constraints of the target schema such that mappings can be found. We have developed a tool to support the generation process. We also propose a mapping adaptation approach to maintain an existing mapping if some changes occur either in the target schema or in the source schemas.