The Java-Framework is used as an abstraction layer for different building data streams and provides var- ious software interfaces (OPC UA, GWT-RPC, etc.) for different processing applications (Excel, Matlab, etc.). To obtain information concerning parameters that are not directly measureable, so called “virtual datapoints” are introduced in the framework. A vir- tual datapoint can be, for example, the energy use of a zone, which represents an aggregation of all en- ergy measurements in this zone.
Generic virtual datapoints (energy use, number of people, etc.) are provided by the framework. Additional virtual data- points can be added by extending the Java class DatapointServer. From the user’s point of view, the same mode of access can be applied to both physical (sensor-based) and virtual datapoints. To provide building data with the widely supported software in- terface OPC Unified Architecture (UA), a generic information model was developed. The OPC UA in- formation model uses the zone information defined in the MySQL database to generate the tree structure shown in Figure 7. The implementation of the OPC UA interface is currently in an early development stage.