Distributed Interactions with Wireless Sensors Using TinySIP for Hospital Automation

In order to seamlessly interact with everyday objects embedded with wireless sensors, we need diverse messaging abstractions that support convenient application-level interactions with sensor nodes. We have developed TinySIP with the goal of providing a unifying messaging protocol that not only supports distributed interactions among sensor nodes but also enables users on a traditional network to interact with the sensor nodes through familiar devices, such as mobile phones and PDAs. TinySIP leverages the communication abstractions provided by the Session Initiation Protocol (SIP), but uses a more compact and energy- efficient message format for communication with resource- constrained nodes. TinySIP supports interaction with sensor nodes using publish-sub scribe, instant messaging, and session-based semantics. We have implemented the TinySIP messaging library on Zigbee motes running TinyOS. In this paper, we describe a prototype application that we have developed that illustrates the use of TinySIP for interacting with sensor nodes, in order to automate processes in a hospital environment. Despite the diversity of sensor network applications and the heterogeneity of the sensor-generated data, our example shows that typical sensor-based interactions can be supported through a set of common communication abstractions. Hence, using a standard application- level messaging protocol, like TinySIP, that supports a common set of communication abstractions which can be used in a variety of sensor-based interactions will benefit sensor network application developers and users.