Data Modeling in the Virtual Observatory Framework

The International Virtual Observatory Alliance Data Model Working Group has developed a set of data models standards to describe the content of astronomical observations and allow for global search across multiple archives provided in the astronomical community. This paper describes the scope of this effort, its timeline, the adopted strategy and highlights the benefits in terms of interoperability with a few examples. The main concepts needed to characterize data sets of interest for a user are exposed: the coverage profile of the data in terms of spatial, spectral, temporal, observable, polarimetric axes; quality indicators such as resolution, accuracy, statistical errors along each of these axes. Also included are the generic resource metadata needed to identify a data file in an publishing archive, including instrument and facility name for instance. How the metadata profile generated from theses data models are put in action in IVOA protocols and applications is also presented. Altogether it provides an overview of the impact of data modeling in the IVOA architecture and how it can provide a general semantic and structural background for astronomical data.