Shangping Ren

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We argue that the specification of an object's functional behavior and the timing constraints imposed on it may be separated. Specifically, we describe RTsynchronizer, a high-level programming language construct for specifying real-time constraints between objects in a distributed concurrent system. During program execution, RTsynchronizers affect the(More)
We give formal semantics for a distributed concurrent object-oriented real-time programming language based on a variant of the actor model which includes an extention enabling the specification of time constraints on messageinvocation. Real-time semantics must capture both the qualitative and quantitative aspects of the language, and provide a meaning for(More)
As computer and Internet technology continue to advance, real-time online services are emerging. Different from traditional real-time applications for which the scheduling objective is to meet task deadlines, the optimization goal for online service systems is to maximize profit obtained through providing timely services. For this class of applications,(More)
In this paper, we introduce a novel utility accrual scheduling algorithm for real-time cloud computing services. The real-time tasks are scheduled non-preemptively with the objective to maximize the total utility. The most unique characteristic of our approach is that, different from the traditional utility accrual approach that works under one single time(More)
Cyber-Physical Systems (CPS) involve communication, computation, sensing, and actuating through heterogeneous and widely distributed physical devices and computational components. The close interactions of these systems with the physical world places <i>events</i> as the major building blocks for the realization of CPS. More specifically, the system(More)
The advent of cloud systems has spurred the emergence of an impressive assortment of Internet services. Recent pressures on enhancing the profitability by curtailing surging dollar costs on energy have posed challenges to, as well as placed a new emphasis on, designing energy-efficient request dispatching and resource management algorithms. What further(More)
In this paper, we study run-time reconfiguration problem for tolerating core failures on NoC many core platforms with following three objectives:(1) maintaining the maximal timing similarity between real-time embedded application' timing properties before and after the system reconfiguration, (2) guaranteeing to meet real-time embedded application's(More)
The focus of this paper is on vulnerabilities which exist in Supervisory Control and Data Acquisition (SCADA) systems. Cyber attacks targeting weaknesses in these systems can seriously degrade the survivability of a critical system. Detailed here is a non-intrusive approach for improving the survivability of these systems without interruption of their(More)