An Energy-Efficient Object Discovery Protocol for Context-Sensitive Middleware for Ubiquitous Computing

Many ubiquitous computing applications may be context-sensitive due to the ambient environments, mobile devices, and other detectable factors. A context-sensitive middleware provides the necessary support to context-sensitive application objects to participate in spontaneous and ad hoc communications with other applications in remote devices whenever suitable contexts exist. A context-sensitive middleware can provide this support effectively if its communication subsystem, such as an Object Request Broker (ORB), can properly discover other objects in devices. This capability is usually known as object discovery protocol. An energy-efficient object discovery protocol is needed to help prolong a device's battery life because many devices in ubiquitous computing environments are battery-powered and, thus, have limited energy sources. In this paper, an energy-efficient object discovery protocol, RKS, for context-sensitive middleware for ubiquitous computing is presented. RKS reduces energy consumption by reducing the amount of information that needs to be sent to remote devices to discover objects. A novel feature of RKS is that it advertises its server-objects' availability only when it detects that these servers can be activated in the current context and when it finds that the neighbor devices have some potential clients that are willing to discover objects. Analytical comparisons of the energy-consumptions are given between RKS and two other protocols for object discovery in context-sensitive middleware. Furthermore, our experimental results, based on the implementations of these protocols and RKS on a context-sensitive middleware test bed, confirm our analytical results in that the RKS conserves more energy than the other two.