The convergence and miniaturisation of a range of information and communication technologies, together with increasing bandwidth availability and near ubiquity of mobile phones, are giving rise to a technological environment in which location-based services (LBS) can realistically develop. In this paper we review the nature of location-based services and the implications for data and spatial queries. In doing so, we put forward a research agenda that arises for geographical information science and engineering. Central to LBS are problems of response time and the information utility of responses to queries and any pushed alerts, where information utility refers to content, timeliness and geographical footprint. Within a publish/subscribe model of LBS provision, we propose mobile space-time envelopes as a novel approach to event brokerage. These envelopes simultaneously provide 'soft clip' pruning of candidate data sets in anticipation of queries, and provide the trigger that subscribers are pertinently in-range for alerts. We present the geometrical, algebraic and algorithmic concepts of mobile space-time envelopes and provide an example of these mobile envelopes in action. We conclude with a discussion of how this initial implementation could be further developed to incorporate added spatio-temporal intelligence.
展开▼
