Abstract: Many applications in the Internet of things (IoI}) decide their next actions according to the occurrences of events with temporal and spatial constraints. In order to help IoT applications to detect spatio-temporal events, the paper built a Pub/Sub middleware OPS4S7.OPS4ST permits users to express in their subscriptions diverse temporal, spatial and logical relationships of events, implements the detection of spatio-temporal events in a distributed way, and can efficiently detect whether the spatio-temporal events to which the users pay attention in their subscriptions occur. The paper also evaluated OPS4ST's matching performance and costs by simulation experiments. I}he experimental results show that OPS4ST's can achieve satisfying performance and acceptable overheads.

Key words: Spatio-temporal event, Event detection, Pub/Sub, Matching algorithm