  The report describes the digital architecture developed for the West
Cambridge Digital Twin, particularly focussed on real-time sensor data
collection and analysis with a privacy framework allowing occupants of the
buildings to be first-class participants in the system. The implementation has
some notable characteristics. In particular 'push' technology is used
throughout such that information streams from the incoming asynchronous
individual sensor events through to the end-user web pages with the absolute
minimum latency, including real-time generated simple and complex events
derived from the the underlying sensor data and the updating of visualisations
such as an in-building heatmap. We believe the ability of the entire system to
respond in the timescale of individual sensor messages to be unique. JSON
structures are used to represent all data types including sensor readings,
sensor types, building objects, organisations and people, with the idea that
JSON-LD may represent a more suitable way than XML/RDF for managing relations
between those objects (such as the 'occupies' relationship of people to
offices, or the 'type' relationship of sensors to sensor types).
