Centralized FITS Metadata Handling Framework at ESO

The European Organization for Astronomical Research in the Southern Hemisphere (ESO) headquartered in Garching, Germany, operates three state-of-the-art observatories in Chile: at La Silla, Paranal and Chajnantor. The observatories produce huge amounts of data, which are transferred to the ESO headquarters and stored in the ESO Archive. The archive also stores the products generated by pipeline processing of raw data by the ESO Quality Control (QC) group. In addition, the Archive also stores science products delivered by the principal investigators. Historically, these three processes were independent from one another which resulted in different metadata handling frameworks for each kind of product. This architecture led to duplicate efforts for building metadata-based services as well as creating challenging scenarios for integrating metadata from different processes. We present the metadata handling framework recently implemented at the European Southern Observatory, in which all metadata from FITS compliant sources are stored in a centralized repository database. The framework allows building metadata-based services in a descriptive way, transparently propagating any modifications/updates performed in the central repository. In addition, through a set of common functions, the framework allows for enrichment of FITS-based metadata with derived values and/or with metadata from other ESO operational databases.