Dynamic scaling method of uTupleSpace data-sharing mechanism for wide area ubiquitous network

A wide area ubiquitous network (WAUN) was proposed as a new network for achieving a ubiquitous/pervasive environment. A WAUN covers a geographically wide area and connects us to a large variety of sensors and actuators distributed in the real world. To detect events and to flexibly control actuators in the real world using this connectivity, we have proposed a data-sharing mechanism called uTupleSpace. The uTupleSpace offers flexible communication in a ubiquitous environment, but it must have scalability to accommodate many programs and a large amount of data. To achieve scalability, we propose the dynamic-help method, which is a new dynamic scaling method. This method can guarantee search completeness and increased throughput in proportion to the increase in server hosts for a large number of device terminals. We also evaluate the proposed method with experiments using a micro-benchmark test. The result shows that the proposed method has enough scalability against the load of a typical application using sensor devices, while it also shows poor scalability against the load of another application using actuator devices. We indicate how to resolve this.