A Unified Specification Framework for Spatiotemporal Communication

Traditionally, network communication entailed the delivery of messages to specific network addresses. As computers acquired multimedia capabilities, new applications such as video broadcasting dictated the need for real-time quality of service guarantees and delivery to multiple recipients. In light of this, a subtle transition took place as a subset of IP addresses evolved into a group-naming scheme and best-effort delivery became subjugated to temporal constraints. With recent developments in mobile and sensor networks new applications are being considered in which physical locations and even temporal coordinates play a role in identifying the set of desired recipients. Other applications involved in the delivery of spatiotemporal services are pointing to increasingly sophisticated ways in which the name, time, and space dimensions can be engaged in specifying the recipients of a given message. In this paper we explore the extent to which these and other techniques for implicit and explicit specification of the recipient list can be brought under a single unified framework. The proposed framework is shown to be expressive enough so as to offer precise specifications for existing communication mechanisms. More importantly, its analysis suggests novel forms of communication relevant to the emerging areas of spatiotemporal service provision in sensor and mobile networks. Currently at Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, CA 94040