Event services are needed for control systems, implementing management of networks and distributed and for many event based applications. In all these applications it is necessary to filter out unwanted events and com...
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Event services are needed for control systems, implementing management of networks and distributed and for many event based applications. In all these applications it is necessary to filter out unwanted events and combine low-level event sequences into a higher level, more abstract event to trigger an action. In this paper we present a flexible and powerful distributed event service which can be used to process and disseminate events for many different applications. The service can be configured dynamically at two levels. Composite events can be defined as rules in terms of event sequences using the GEM notation. These rules can be loaded, removed, enabled and disabled dynamically within event monitoring interpreters. Interpreters and event disseminator components can then be dynamically configured onto physical nodes within the system using the Darwin configuration environment to distribute the monitoring close to where events are generated. This reduces network traffic caused by event generation in large systems.
In distributedsystems, object replication is used to improve the availability and performance of applications in the presence of failures. When determining the configuration of a replicated object (i.e., number and l...
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In distributedsystems, object replication is used to improve the availability and performance of applications in the presence of failures. When determining the configuration of a replicated object (i.e., number and location of replicas), a number of often conflicting factors need to be considered, e.g., the availability and performance requirements of the object. However, application specific knowledge about the objects, such as any inter-dependencies, is typically not accounted for. In many applications this information can affect an object's availability. distributedsystems which support replication typically give users only basic control over the configuration of a replicated object, such as the number or location of individual replicas. Expressing application specific knowledge is not possible. We have designed and implemented a replication sub-system allowing applications to control these aspects of replication. This system allows the efficient replication of an arbitrary number of objects with arbitrary inter-dependencies.
Complex distributed applications are often developed incrementally while they are in active use. Programming and runtime environments must allow software designers to make these changes easily and efficiently. This mu...
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Complex distributed applications are often developed incrementally while they are in active use. Programming and runtime environments must allow software designers to make these changes easily and efficiently. This must be provided within the appropriate framework for modeling, analysis and correct execution that is essential for complex applications. The key to supporting reconfiguration of large-scale applications is providing efficient abstraction and composition mechanisms. By separating specification of well-defined components from the component interaction and composition behavior, we allow designers to implement easily replaceable components and changeable interaction behavior. The abstraction mechanism simplifies development of large-scale reconfigurable applications by hiding implementation details. The facility also include automatic analytical tools for checking consistency, reachability and dependency in the behavior of interacting components. These tools are essential for development and runtime support of large-scale and reconfigurable decentralized applications.
Over the past twenty years considerable advances have been made in new optical fiber sensor technology able to measure physical parameters as a function of linear position. Such advances are of interest to the civil e...
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ISBN:
(纸本)0819421650
Over the past twenty years considerable advances have been made in new optical fiber sensor technology able to measure physical parameters as a function of linear position. Such advances are of interest to the civil engineering community who have the problem of implementing measurement systems which can provide data on the structural state of health of large constructions such as bridges. This paper reviews the background to the measurement problem and outlines the relevant optical fiber techniques which have been considered in this context. The potential and the limitations of these measurement approaches is discussed.
Many kinds of instruments and sensors are used during condition monitoring of diesel engines. In this paper, the multisensor fusion technology is introduced to raise the accuracy and fault tolerance ability effectivel...
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ISBN:
(纸本)7505338900
Many kinds of instruments and sensors are used during condition monitoring of diesel engines. In this paper, the multisensor fusion technology is introduced to raise the accuracy and fault tolerance ability effectively. Artificial neural network is used to do the fusion in this study. Aiming at the problems of diesel engine condition monitoring, the application of multisensor fusion technology in oil analysis is implemented and an experiment is given in the end.
Our approach to dynamic configuration is based on building a model of reconfigurable applications. The model documents applications according to the Configuration paradigm and for each component, captures structural c...
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Our approach to dynamic configuration is based on building a model of reconfigurable applications. The model documents applications according to the Configuration paradigm and for each component, captures structural constraints and behavioural information. The model presents change administrators with an abstract interface to dynamic configuration management. Change is initiated by submitting a version descriptor to the configuration manager;much of the low-level and error-prone activities of dynamic configuration are automated. Synchronisation of dynamic configuration with the application and management of persistent state are fundamental to preserving an application's integrity. In this paper we present our synchronisation mechanism, which adopts atomic operations for both intra- and inter- component computation. The problems of persistent state management are simplified by our synchronisation model. We also expose the difficulties and propose solutions for managing composite components and components whose operations are constrained.
Given a certain class C of reconfigurations, deemed to be potentially important for a given system, we define a reconfiguration suite Sc to be a set of primitive operations that satisfy the following conditions: An re...
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Given a certain class C of reconfigurations, deemed to be potentially important for a given system, we define a reconfiguration suite Sc to be a set of primitive operations that satisfy the following conditions: An reconfiguration in C can be carried out by a sequence of primitive from Sc. The correctness of Sc should be independent of the functionality of the system, and invariant of its reconfigurations (for a given set of possible configurations of the system at hand). We describe a mechanism for implementing such reconfiguration suites, for a system that operates under law-governed interaction (LGI), currently supported by an experimental toolkit called Moses. LGI is a mode of interaction between the members of a given group (or system) of agents, which is governed by an explicit and strictly enforced set of rules, called the law of this group. The existence of such a law under LGI provides us with an architectural model of the system, which can be made to include the definition of reconfiguration suites.
The paper presents an approach to the specification and verification of real-Time hybrid systems using duration calculus (DC). By introducing a formula int to DC to express the intervals of time between two ticks of t...
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We present a uniform construct of parallel programming for a set of image processing tasks based on our distributedcomputing primitive (DCP) concept. Our target architecture is a heterogeneous computing network syste...
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We present a uniform construct of parallel programming for a set of image processing tasks based on our distributedcomputing primitive (DCP) concept. Our target architecture is a heterogeneous computing network system consisting of various high performance workstations connected through a local area network. We show that DCP has advantages over non-primitive PVM-based parallel approaches in three aspects: ease-of-use, automation, and optimization.
Real-time systems are distributed, and require reliability. The formal verification and specification are important for real-time systems. In this paper, in order to obtain reliability, we think the notion of dense-ti...
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Real-time systems are distributed, and require reliability. The formal verification and specification are important for real-time systems. In this paper, in order to obtain reliability, we think the notion of dense-time and probabilities are necessary. We propose the following methods in order to specify and verify performance properties in dense time model. (1) Probabilistic and dense time statecharts and temporal logic (2) An automatic verification method by probabilistic and dense time model checking.
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