The query language framework STARQL (Streaming and Temporal ontology Access with a Reasoning-based Query Language) is an experimental implementation based on PostgreSQL. It reduces the often too large amount of data produced by streams by applying a sliding time frame. Doing so, it provides a smaller dataset to query but which is still relevant since data are refreshed continuously from the stream. Unlike others, it also features unique expressiveness in its language for inter-ABox reasoning while conditions prevent logical inconsistencies occurrances w.r.t. the conceptual model.
The Northstream demonstrator is specifically developed to address the querying of temporal data using semantic technologies.