SUMMARYLock‐based resource sharing protocols for single processor systems are well understood and supported in programming languages such as Ada and the Real‐Time Specification for Java, and in Real‐Time Operating Systems, such as those that conform to the Real‐Time POSIX standard. In contrast, multiprocessor resource sharing protocols are still in their infancy with no agreed best practices, and yet current real‐time programming languages and operating systems claim to be suitable for multiprocessor applications. This paper reviews the currently available multiprocessor resource allocation policies and analyzes their applicability to the main industry standard real‐time programming languages. It then proposes a framework that allows programmers to define and implement their own locking policy. A prototype implementation of the framework for Ada is presented and evaluated. Copyright © 2012 John Wiley & Sons, Ltd.

Localization of the nodes in Wireless sensor networks (WSNs) is an important research issue, since it can enhance the efficiency in computation and minimize the power consumption of the nodes. In this paper, a novel localization algorithm is proposed to estimate the location information of the normal nodes with help of few beacon nodes and angle information of the anchor nodes. Our localization scheme can use at most three beacon nodes to find location information of any normal node in a distributed manner. Besides, we give the theoretical basis for determining the localization error using probability distribution function. Our performance analysis shows that there is a tradeoff between deployed number of beacon nodes and localization error and average localization time of the network can be increased with deployed number of normal nodes.

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As from Ada 2005, the language has supported different dispatching policies including fixed priority (FP) and earliestdeadline first (EDF). EDF dispatching can be applied across the whole range of priorities or across a restricted range. In this way, EDF scheduling is integrated into a FP framework. Baker's Stack Resource Policy (SRP) is also integrated with Ada's immediate priority ceiling protocol to support resource sharing using protected objects. However, with the introduction of support for global, partitioned and cluster scheduling for multiprocessor systems, the use of protected objects in applications needs to be re-evaluated. This is because Ada does not completely define how protected objects are accessed in a multiprocessor environment and because the SRP cannot be directly applied to multiprocessors. This paper reviews the currently available multiprocessor resource allocation policies and analyzes their applicability to Ada. It proposes some new Ada mechanisms that would facilitate the programming of a variety of protected object access protocols.