No abstract

Modern applications distributed across networks such as the Internet may need to evolve without compromising application availability. Object systems are well suited for runtime upgrade, as encapsulation clearly separates internal structure and external services. This paper considers a mechanism for dynamic class upgrade, allowing class hierarchies to be upgraded in such a way that the existing objects of the upgraded class and of its subclasses gradually evolve at runtime. The mechanism is integrated in Creol, a high-level language which targets distributed applications by means of concurrent objects communicating by asynchronous method calls. The dynamic class construct is given a formal semantics in rewriting logic, extending the semantics of the Creol language.

No abstract

Extending the lifetime of wireless sensor networks remains the most challenging and demanding requirement that impedes large-scale deployments. The basic operation in WSNs is the systematic gathering and transmission of sensed data to a base station for further processing. During data gathering, the amount of data can be large sometimes, due to redundant data combined from different sensing nodes in the neighborhood. Thus the data gathered need to be processed before being transmitted, in order to detect and remove redundancy, which can impact the communication traffic and energy consumption of the network in a negative way. In this paper, we propose an algorithm to measure similarity between the data collected toward the base station(relative to a specific event monitoring), so that an aggregator sensor sends a minimum amount of information to the base station in a way that the latter can deduce the source information of sensing neighbors nodes. Further, our experimental results demonstrate that the communication traffic and the number of bits transmitted can be minimized while preserving accuracy on the base station estimations.