Design, realization and user evaluation of the SmartVortex Visual Query System for accessing data streams in industrial engineering applications

• We investigated the issues of visually querying data streams.
• We developed a Visual Query System for a real data stream management.
• We evaluated such a system with an usability study in two phases, and compared with state-of-the-art tools.
• We report the evaluation results.

Objective: In this paper we present a Visual Query System, which allows users to graphically build queries over data streams and traditional relational data. The Visual Query System runs on top of a DSMS (Data Stream Management System).Methods: The system has been designed and implemented following the user-centered design approach. Two different releases of the system have been incrementally and iteratively designed and evaluated. The first release has been evaluated using heuristic evaluation. The second release, whose design was a refinement based on the results of the foregoing heuristic evaluation, was evaluated by several users. Moreover, a comparative evaluation involving users has been conducted on the second release.Results: The paper presents the visual query system, and the results ofthe various evaluations.Conclusion: Visual Query Systems for data streams are an effective tool for industrial engineers in querying and analyzing data streams from equipments.Practice and implications: The proposed visual query system has been employed in real industrial scenarios in order to visually query and analyze data streams produced by industrial machines.