Data-centric Graphical User Interface of the ATLAS Event Index Service

ATLAS Event Index Service keeps references to all events real and simulated events. Hadoop Map files and HBase tables are used to store the Event Index data, a subset of data is also stored in the Oracle database. Several user interfaces are currently used to access and search the data. From the simple command line interface, through programatical API to sophisticated Graphical Web Services. This paper describes the most recent, highly interactive Web Service. It provides a dynamic graph-like overview of all available data (and data collections). Data are shown together with their relations, like paternality of overlaps. Each data entity then gives users a set of actions availabble for the referenced data. Some actions are provided directly by the Event Index system, others are juste interfaces to different ATLAS services. In many cases, specialised views are offered for detailed data inspection - histograms, Venn diagrams,... This paper presentation documents the current status of the service, its possibilities and performance. The future system evolution to the new Event Index Architecture based on the Apache Phoenix is also described as well as possible extention to more general framework for giving a new, more intuitive access to experiment data.