Implementing a practical spatio-temporal composite event language

  • Authors:

  • Ken Moody;Jean Bacon;David Evans;Scarlet Schwiderski-Grosche

  • Affiliations:

  • Computer Laboratory, University of Cambridge, Cambridge, UK;Computer Laboratory, University of Cambridge, Cambridge, UK;Computer Laboratory, University of Cambridge, Cambridge, UK;Microsoft Research, Cambridge, UK

  • Venue:
  • From active data management to event-based systems and more
  • Year:
  • 2010

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Abstract

An earlier paper introduced SpaTeC, a composite event language that enables simultaneous matching of event occurrences over space and time. The driving case study is taken from a paper that describes techniques for monitoring small animals in New Zealand. The semantics of SpaTeC is presented in detail with the aid of the case study, but the syntax is essentially mathematical. This paper describes a programming language based on the SpaTeC model, illustrating it through a practical application, the analysis of GPS traces of buses serving Cambridge, UK. We describe some of the questions that Stagecoach, the bus operator, wish to have answered, and use these to motivate our extensions to SpaTeC. Composite event patterns are essentially those of the earlier paper, with the addition of primitive patterns, which enforce restrictions on the space and/or time of event occurrences. Data fields identified during pattern matching can be tested by predicates that further restrict the relevant combinations of primitive events. We show how the language can be used to answer questions posed by Stagecoach and discuss its realisation.