Manufactured objects and everyday devices are becoming increasingly network enabled, providing constant communication and interaction while producing a surfeit of data and events. The question then becomes, how can one locate some set of events that took place at a specified location and at a particular time? This process has to be automatic, based on a pattern language with the appropriate temporal and spatial operators to specify the events that users are after.

This paper is focused on just such an approach. The authors provide a composite subscription language and a system architecture that can specify and detect spatiotemporal events based on the publish/subscribe model. There are many good ideas in the paper. The use of publish/subscribe demonstrates the principle of separation of concerns, providing a sense of asynchrony between the components.

The section on related work is very good, providing a broad but succinct overview of the major resources in the area. The paper combines interval temporal logic with the spatial logic of RCC-8.

The authors have a salutary ability to distill theoretical work in temporal and spatial logics to come up with working language primitives. The choices of the spatial and temporal operators are exemplary, although the notations are confusing. The described scenarios were difficult to understand because the notation issues somewhat obscured the core ideas. The Backus normal form description of the grammar was good.

It would have been desirable to see a description of the operational semantics induced by the grammar. Nevertheless, this is a good paper that describes a useful approach to the Internet of Things.