Behavioral specification of distributed software componentinterfaces

Networked computers are finding their way into a broader range of environments, from corporate offices to schools, homes, and shirt pockets. This new computing model fosters the development of distributed software components that communicate with one another across the underlying networked infrastructure. A distributed software component can be plugged into distributed applications that may not have existed when it was created. The intention is that many developers will reuse distributed software components to build new systems. An interface definition language usually is used to describe a distributed software component's interface. However, a notable limitation of current IDLs is that they generally only describe the names and type signatures of the component's attributes and operations. Current IDLs don't formally specify the behavior of the software component's operations. To help solve these problems, the authors have developed Biscotti (behavioral specification of distributed software component interfaces), a Java extension that enhances Java remote method invocation interfaces with Eiffel-style preconditions, postconditions, and invariants     

A distributed specification model and its prototyping

A specification model is described that is based on the finite-state machine but is distributed. The model allows the user to decompose a large system into separate views. Each view is a complete system in itself, and reveals how the whole system would behave as seen from a certain angle. Put together, the combined views present a complete picture of the whole system. The complexity of a large centralized system is thus distributed and subdued. The author offers a simple execution scheme for the model. Using a high-level state-transition language called SXL, constructs in the model are expressed as preconditions and postconditions of transitions. The execution scheme allows all the views in the model to proceed in a parallel but harmonious way, producing a working prototype for the modeled system     

Formal specification and integration of distributed security policies

We propose in this paper the Security Policy Language (SePL), which is a formal language for capturing and integrating distributed security policies. The syntax of SePL includes several operators for the integration of policies and it is endowed with a denotational semantics that is a generic semantics, i.e., which is independent of any evaluation environment. We prove the completeness of SePL with respect to set theory. Furthermore, we provide a formalization of a large subset of the eXtensible Access Control Markup Language (XACML), which is the well-known standard informal specification language of Web security policies. We also provide a semantics for XACML policy combining algorithms.     

基于LabVIEW的无线分布式传感网络控制系统的研究

为了满足无线分布式传感网络中仪器间的无线通信和实验数据的统一管理和控制,以LabVIEW为开发工具,采用PC机多线程技术和虚拟仪器技术,构建了基于LabVIEW的无线分布式传感网络的控制系统,阐述了控制系统的硬件组成和软件设计方法,分析了在LabVIEW平台下,数据显示、分析、存储和通信等方面的特点。     

Algebraic specification and proof of a distributed recovery algorithm

An algebraic specification is given of an algorithm for recovery from catastrophe by a deterministic process. A second version of the algorithm also includes check-points. The algorithms are formulated in the notations of Communicating Sequential Processes (Hoare 1985) and the proofs of correctness are conducted wholly by application of algebraic laws (together with the unique fixed point theorem). He Jifeng received the B.S. degree in mathematics from Fudan University, Shanghai (China), in 1965. Then he taught in the department of mathematics, Shanghai Normal University. In 1972 he moved to East China Normal University where he was a lecturer of computer science. Since September 1986 he has been a professor of computer science at East China Normal University. He is currently working at Oxford University Computing Laboratory. His major research interests are programming language semantics, software engineering and distributed computing. Tony Hoare is Professor of Computation at the University of Oxford. He received his MA from Oxford in Classical Languages, Literature, History and Philosophy. He worked for eight years as programmer, manager and research scientist with a small computer manufacturer. He is the recipient of several honours for his contributions to the study of computer programming languages, and is generally famed for Hoare's Law: inside every large program there is a small program trying to get out.     

Modeling distributed real-time applications with specification PEARL

The methodology of hardware/software co-design of embedded control systems with Specification PEARL is presented. Hardware and software are modeled with the language Specification~PEARL, which has its origins in standard Multiprocessor~PEARL. Its usefulness is enhanced for modeling hierarchical and asymmetrical multiprocessor systems, and by additional parameters for schedulability analysis. Graphical symbols are introduced for its constructs to enable graphical modeling while maintaining the semantical background. It is meant to be a superlayer for programs, based on the PEARL programming model. To model program tasks, Timed State Transition Diagrams have been defined. The model of a co-designed system is verified for feasibility with co-simulation. The resulting information should be used when considering changes in a current design with the goal of producing a temporally feasible model. To support dynamic re-configurations, configuration management is introduced into the models. Since UML is becoming a de facto standard also for designing embedded control systems, and since Timed State Transition Diagrams and State Chart Diagrams share great similarity, an interface of the methodology to UML 2 is defined, using UML's extension mechanisms.     

Robust distributed computing and sensing algorithm

Sensors that supply data to computer systems are inherently unreliable. When sensors are distributed, reliability is further compromised. How can a system tell good sensor data from faulty? A hybrid algorithm combines proposed solutions to address the problem     

Gain of optical distributed sensing in distributed parameter systems

A real time holographic sensing technique is introduced and its advantages arc investigated from the filtering and control point of view. The feature of holographic sensing is its capability to make distributed measurements of the position and velocity of moving objects, such as a vibrating flexible space structure. This study is based upon the distributed parameter models of linear time-invariant systems, particularly including the linear oscillator equations describing the vibration of large flexible space structures. The general conclusion is that application of optical distributed sensors brings gain in the situation where Kalman filtering is necessary for state estimation. In this case, both transient and steady stale filtering error covariance becomes smaller. This in turn results in smaller cost in the LQG problem.     

Towards formal specification of a distributed computing system

Onboard spacecraft computing system is a case of a functionally distributed system that requires continuous interaction among the nodes to control the operations at different nodes. A simple and reliable protocol is desired for such an application. This paper discusses a formal approach to specify the computing system with respect to some important issues encountered in the design and development of a protocol for the onboard distributed system. The issues considered in this paper are concurrency, exclusiveness and sequencing relationships among the various processes at different nodes. A 6-tuple model is developed for the precise specification of the system. The model also enables us to check the consistency of specification and deadlock caused due to improper specification. An example is given to illustrate the use of the proposed methodology for a typical spacecraft configuration. Although the theory is motivated by a specific application the same may be applied to other distributed computing system such as those encountered in process control industries, power plant control and other similar environments.     

Control specification language for distributed computation in mis

Some principles of on-line computation in a distributed computing environment are proposed. These principles are based on a semantic superstructure over a labeled multigraph, intended for formalized representation of MIS distributed information technologies.Translated from Kibernetika, No. 4, pp. 40–44, July–August, 1990.     

The design and specification of post-processors for numerical control programming

The role of the post-processor in computer programming systems for numerically controlled machines is described. Although many of the points discussed apply to the special purpose programs available, attention is concentrated on the position of the post-processor within the general purpose systems such as APT and NELAPT.

The design of modular programs which allow rapid adaptation for different machine tools is considered in detail and the features of an adequate user specification are described.     

一种分布式协作频谱感知技术

构造认知用户的网络模型为马尔科夫随机场,应用BP算法和加权BP算法来协助分布式网络中的决策融合,利用加权的BP算法更有效地解决阴影衰落和恶意节点所导致的问题.这种方法的性能优于现有的分布式网络中的大数判决等其他多数算法的性能.采用MATLAB进行仿真,验证了分析结果.     

Integrated distributed sensing and active vibration suppression of flexible manipulators using distributed piezoelectrics

Structural oscillation of flexible robot manipulators would severely hamper their operation accuracy and precision. This article presents an integrated distributed sensor and active distributed vibration actuator design for elastic or flexible robot structures. The proposed distributed sensor and actuator is a layer, or multilayer of piezoelectric material directly attached on the flexible component needed to be monitored and controlled. The integrated piezoelectric sensor/actuator can monitor the oscillation as well as actively and directly constrain the undesirable oscillation of the flexible robot manipulators by direct/converse piezoelectric effects, respectively. A general theory on the distributed sensing and active vibration control using the piezoelectric elements is first proposed. An equivalent finite element formulation is also developed. A physical model with distributed sensor/actuator is tested in laboratory; and a finite element model with the piezoelectric actuator is simulated. The distributed sensing and control effectiveness are studied.     

On the specification and implementation of distributed systems using NMDS and LIPS

This paper describes a graphical notation called NMDS and an implementation language called LIPS for producing distributed systems. NMDS is a set of notations based on Role Activity Diagrams with features for expressing concurrency, dataflow and communication and it lends itself to elicitation and verification while expressing concurrency unambiguously in a concise manner. It also fits in with the syntax and semantics of LIPS. LIPS is a distributed message passing language that promotes the separation of communication from computation by using the concept of guarded processes. One of the major advantages of using NMDS with LIPS is that reverse engineering of LIPS programs can easily be achieved.     

Formal methods integration for the specification of dependable distributed systems

This paper describes a real-world case study in the specification and analysis of dependable distributed systems. The case study is an automated transport system with safety requirements. In order to manage the complexity of the problem of specifying the dynamic behavior of the whole system, a compositional approach is used, based on the integration of the trace logic of the Communicating Sequential Processes (CSP) theory, and stochastic Petri nets (SPNs). It is argued that the integration of different formal methods is a useful approach in the definition of practical engineering methodologies for the specification, design and analysis of complex dependable distributed systems.     

The design of distributed control computer systems

The top-down approach in the design of Distributed Control Computer Systems, DCCS, is presented. The starting point of the study is three statements: (i) the design approach should be production process control oriented; (ii) for real time process control applications, computer networks require an efficient communication subsystem, the most important features of which are high reliability and short message transmission times and (iii) recent research has shown that the tools and methodologies used in both computing and control should be complementary to each other in order to solve some of the distributed control computer system/distributed computer control system design problems. The paper contains the design problems of distributed control computer systems, the presentation of the methods and tools for the study and design of the DCCS, the top-down approach in the design of the DCCS, and examples of two design stages.     

A model for specification and synchronization of data for distributed multimedia applications

As network technology provides the capability to handle multimedia traffic and the demand of multimedia services increases, protocols are required for effective communication of multimedia data in a distributed environment. Synchronization is one of the key issues in a multimedia system. Most of the current approaches do not support an integrated solution to the problem of synchronization. In this paper we propose a mechanism for synchronization of multimedia data in distributed environment where the accuracy of the protocol can be tailored to the application. The system model supports live and video-on-demand service. We present a scheme where the specification of the temporal requirements provided by the application can be directly mapped to obtain the information necessary to enforce the synchronization required. We present two examples of specifying the temporal requirements and process of obtaining the information and present performance results of our simulation studies.     

Foundations of distributed multiscale computing: Formalization,specification, and analysis

Inherently complex problems from many scientific disciplines require a multiscale modeling approach. Yet its practical contents remain unclear and inconsistent. Moreover, multiscale models can be very computationally expensive, and may have potential to be executed on distributed infrastructure. In this paper we propose firm foundations for multiscale modeling and distributed multiscale computing. Useful interaction patterns of multiscale models are made predictable with a submodel execution loop (SEL), four coupling templates, and coupling topology properties. We enhance a high-level and well-defined Multiscale Modeling Language (MML) that describes and specifies multiscale models and their computational architecture in a modular way. The architecture is analyzed using directed acyclic task graphs, facilitating validity checking, scheduling distributed computing resources, estimating computational costs, and predicting deadlocks. Distributed execution using the multiscale coupling library and environment (MUSCLE) is outlined. The methodology is applied to two selected applications in nanotechnology and biophysics, showing its capabilities.