ntegrated Access of Distributed and Heterogeneous Astronomical Data Resources

Astronomical data resources have features of the long-term accumulation, high volume, distributed storage, and managed by the diverse database software. One of the important goals in Virtual Observatory(VO) is to provide an uniformed way to access these distributed and heterogeneous data resources for astronomers. A grid solution(Virtual Observatory Data Access Service, VO-DAS) is designed in this paper. Astronomical catalogue data, image data and spectroscopy data, which have different metadata, are wrapped by OGSA-DAI(DataNode). VO-DAS implements automatic discovery of DataNodes and supports federation data access upon them. This makes it possible for multi-band cross matching of astronomical objects. VO-DAS supports related specifications published by International Virtual Observatory Alliance(IVOA) so that interoperability is achieved. A series of simple and efficient application interface are designed for developing versatile high-level applications based on VO-DAS. Two science cases based on VO-DAS confirm its feasibility.