ODP enterprise viewpoint specification

The Open Distributed Processing (ODP) standardisation initiative has led to a framework by which distributed systems can be modelled using a number of viewpoints. These include an enterprise viewpoint, which focuses on the objectives and policies of the enterprise that the system is meant to support. Although the ODP reference model provides abstract languages of relevant concepts, it does not prescribe particular techniques that are to be used in the individual viewpoints. In particular, there is a need to develop appropriate notations for ODP enterprise specification, in order to increase the applicability of the ODP framework. In this paper, we tackle this concern and develop a specification language to support the current draft of the enterprise viewpoint. In doing so, we analyse the current definition of the ODP enterprise viewpoint language. Using the Unified Modelling Language (uml), a meta-model of the core concepts and their relationships is constructed, and we also investigate to what extent the uml can be used for enterprise viewpoint specification. We, then, focus on the expression of enterprise policies that govern the behaviour of enterprise objects. We develop a policy language, which is a combination of structured English and simple predicate logic and is built on top of the formal object-oriented specification language Object-Z, into which the complete language is translated. We illustrate the ideas in the paper with a case study that presents an enterprise specification of a library support system.     

An RM-ODP enterprise view for spatial data infrastructures

Spatial Data Infrastructures (SDIs) are large, open, distributed and standards-based information systems which intend to facilitate and promote the use of spatial data and spatial services on the Internet. Spatial data describe information tied with locations on Earth, while spatial services allow to manipulate spatial data following a Service Oriented Architecture. This paper proposes to model SDIs as federations of autonomous communities following the enterprise language of the ITU-T and ISO/IEC ‘Reference Model of Open Distributed Processing’ (RM-ODP), and the recently approved ‘Use of UML for ODP Systems Specifications’ (UML4ODP). The enterprise language of the RM-ODP provides a conceptual foundation to address several aspects of SDIs not previously considered from a systems architecture point of view. The use of UML4ODP provides a modeling language to facilitate the exchange of knowledge about SDI, and it is an opportunity to try this recent standard for a class of large and complex systems.     

H∞ decentralized fuzzy model reference tracking controldesign for nonlinear interconnected systems

In general, due to the interactions among subsystems, it is difficult to design an H_∞ decentralized controller for nonlinear interconnected systems. The model reference tracking control problem of nonlinear interconnected systems is studied via H_∞ decentralized fuzzy control method. First, the nonlinear interconnected system is represented by an equivalent Takagi-Sugeno type fuzzy model. A state feedback decentralized fuzzy control scheme is developed to override the external disturbances such that the H∞ model reference tracking performance is achieved. Furthermore, the stability of the nonlinear interconnected systems is also guaranteed. If states are not all available, a decentralized fuzzy observer is proposed to estimate the states of each subsystem for decentralized control. Consequently, a fuzzy observer-based state feedback decentralized fuzzy controller is proposed to solve the H_∞ tracking control design problem for nonlinear interconnected systems. The problem of H _∞ decentralized fuzzy tracking control design for nonlinear interconnected systems is characterized in terms of solving an eigenvalue problem (EVP). The EVP can be solved very efficiently using convex optimization techniques. Finally, simulation examples are given to illustrate the tracking performance of the proposed methods     

Using Maude to write and execute ODP information viewpoint specifications

The aim of the open distributed processing (ODP) information viewpoint is to describe the semantics of the information and of the information processing in a system, from a global point of view, without having to worry about other considerations, such as how the information will be finally distributed or implemented or the technology used to achieve such implementation. Although several notations have been proposed to model this ODP viewpoint, they are not expressive enough to faithfully represent all the information concepts, or they tend to suffer from a lack of (formal) support, or both. In this paper, we explore the use of Maude as a formal notation for writing ODP information specifications. Maude is an executable rewriting logic language especially well suited for the specification of object-oriented open and distributed systems. We show how Maude offers a simple, natural, and accurate way of modeling the ODP information viewpoint concepts, allows the execution of the specifications produced, and offers good tool support for reasoning about them.     

一个基于MultiServer系统的分布计算模型

本文针对开放分布式处理的要求，分析了传统分布计算模型Ｃｌｉｅｎｔ／Ｓｅｒｖｅｒ的不足，提出和设计了一个基于ＭｕｌｔｉＳｅｒｖｅｒ系统的分布计算模型，它具有面向对象、服务静态和动态调用、对多服务关系层次的支持等优点，具有较好的服务透明性、可扩充性和容错性．     

Writing and executing ODP computational viewpoint specifications using Maude

The Reference Model of Open Distributed Processing (RM-ODP) is a joint standardization effort by ITU-T and ISO/IEC for the specification of large open distributed systems. RM-ODP is becoming increasingly relevant now because the size and complexity of large distributed systems is challenging current software engineering methods and tools, and because international standards have become key to achieve the required interoperability between the different parties and organizations involved in the design and development of complex systems. RM-ODP defines five viewpoints for decomposing the design activity into separate areas of concern. One of the RM-ODP viewpoints, the computational viewpoint, focuses on the basic functionality of the system and its environment, independently of its distribution. Although several notations have been proposed to model the ODP computational viewpoint, either they are not expressive enough to faithfully represent all its concepts, or they tend to suffer from a lack of formal support. In this paper we introduce the use of Maude as a formal notation for writing and executing ODP computational viewpoint specifications. Maude is an executable rewriting logic language specially well suited for the specification of object-oriented open and distributed systems. We show how Maude offers a simple, natural, and accurate way of modeling the ODP computational viewpoint concepts, allows the execution of the specifications produced, and offers good tool support for reasoning about them.     

Konstruktion von Referenzmodellierungssprachen Ein Ordnungsrahmen zur Spezifikation von Adaptionsmechanismen für Informationsmodelle

Construction of Reference Modeling Languages — A Framework for the Specification of Adaptation Mechanisms for Conceptual Information Models Reference modeling languages differ from each other as they use different model types (such as process or data models) and as they provide different mechanisms that allow an adaptation of the reference model to specific contexts. The developer of the reference modeling language has to decide which adaptation technique he wants to use (e. g. configuration, aggregation, instantiation, specialization or analogy construction) and which of these techniques he wants to integrate into the language specification. In this paper, these adaptation techniques are compared, and reference solutions for the specification of extended reference modeling languages are proposed. The introduced solutions are structured by a methodical framework that assigns modeling examples and meta-models as well as meta-meta-models to the different adaptation techniques. Based on this framework, possible combinations of configurative adaptation mechanisms with aggregative, instantiation based, specialization based and analogy construction based mechanisms are discussed.     

Shaping user input: a strategy for natural language dialogue design

Traditional approaches to natural language dialogue interface design have adopted ordinary human-human conversation as the model for online human-computer interaction. The attempt to deal with all the subtleties of natural dialogues, such as topic focus, coherence, ellipsis, pronominal reference, etc. has resulted in prototype systems that are enormously complex and computationally expensive.

In a series of experiments^†, we explored ways of minimizing the processing burden of a dialogue system by channeling user input towards a more tractable, though still natural, form of Englishlanguage questions. Through linking a pair of terminals, we presented subjects with two different dialogue styles as a framework for online help in the domain of word-processing. The first dialogue style involved ordinary conversational format. The second style involved a simulation of an automated dialogue system, including apparent processing restrictions and ‘system process messages’ to inform the subject of the steps taken by the system during query analysis. In both cases human tutors played the role of the help system. After each dialogue session, subjects were interviewed to determine their assessments of the naturalness and usability of the dialogue interface.

We found that user input became more tractable to parsing and query analysis as the dialogue style became more formalized, yet the subjective assessment of naturalness and usability remained fairly constant. This suggests that techniques for channeling user input in a dialogue system may be effectively employed to reduce processing demands without compromising the benefits of a natural language interface. Theoretically, this data lends support to the hypothesis that unrestricted human-human conversation is not the most appropriate model for the design of human-computer dialogue interfaces.     

Applying formal methods to standard development: The open distributed processing experience

Since their introduction, formal methods have been applied in various ways to different standards. This paper gives an account of these applications, focusing on one application in particular: the development of a framework for creating standards for Open Distributed Processing (ODP). Following an introduction to ODP, the paper gives an insight into the current work on formalising the architecture of the Reference Model of ODP (RM-ODP), highlighting the advantages to be gained. The different approaches currently being taken are shown, together with their associated advantages and disadvantages. The paper concludes that there is no one all-purpose approach which can be used in preference to all others, but that a combination of approaches is desirable to best fulfil the potential of formal methods in developing an architectural semantics for ODP.     

From patterns to frameworks to parallel programs

Object-oriented programming, design patterns, and frameworks are abstraction techniques that have been used to reduce the complexity of sequential programming. This paper describes our approach of applying these three techniques to the more difficult parallel programming domain. The Parallel Design Patterns (PDP) process, the basis of the CO₂P₃S parallel programming system, combines these techniques in a layered development model. The result is a new approach to parallel programming that addresses correctness and openness in a unique way. At the topmost development layer, a customized framework is generated from a design pattern specification of the parallel structure of the program. This framework encapsulates all of the structural details of the pattern, including communication and synchronization, to prevent programmer errors and ensure correctness. Lower layers are used only for performance tuning to make the code as efficient as necessary. This paper describes CO₂P₃S, based on the PDP process, and demonstrates it using an example application. We also provide results from a usability study of CO₂P₃S.     

Current techniques for measuring motion

The sports scientist and the ergonomist, although sharing a common disciplinary background, pursue fundamentally different goals. The patterns of approach to the analysis of movement they adopt are, nevertheless, similar and a model of this approach is presented. Some potential sources of error associated with each stage of the process are identified.

In measuring motion in sport, cinematography has played a dominant role. The method has obvious advantages; but analysing film is a slow, pedestrian task, and subject to human error. Where an investigator is experienced and understands his problem clearly he can often achieve his aims with a limited number of measurement variables. This may also meanhe can adopt automatic and specific techniques of acquiring information. Such methods include alternative photographic techniques, but also involve the specialised transducers and automatic analysers that are now burgeoning in the field. Some of these techniques are discussed.     

A computational model for static data flow machines

Computer architects have been constantly looking for new approaches to design high-performance machines. Data flow and VLSI offer two mutually supportive approaches towards a promising design for future super-computers. When very high speed computations are needed, data flow machines may be relied upon as an adequate solution in which extremely parallel processing is achieved.

This paper presents a formal analysis for data flow machines. Moreover, the following three machines are considered: (1) MIT static data flow machine; (2) TI's DDP static data flow machine; (3) LAU data flow machine.

These machines are investigated by making use of a reference model. The contributions of this paper include: (1) Developing a Data Flow Random Access Machine model (DFRAM), for first time, to serve as a formal modeling tool. Also, by making use of this model one can calculate the time cost of various static data machines, as well as the performance of these machines. (2) Constructing a practical Data Flow Simulator (DFS) on the basis of the DFRAM model. Such DFS is modular and portable and can be implemented with less sophistication. The DFS is used not only to study the performance of the underlying data flow machines but also to verify the DFRAM model.     

Towards integration of service and network management in TINA

The Telecommunications Information Networking Architecture (TINA) defines a framework to support the rapid and flexible deployment and management of a wide range of multi-media, multi-party services in a multi-vendor telecommunications environment. The TINA approach applies opendistributed processing (ODP) and object-oriented design techniques to specify the control and management of the telecommunications services and infrastructure. Management in TINA is applied to the different components of the architecture, services and resources, and to thedistributed processingenvironment (DPE) that provides distribution transparencies and communication capabilities among TINA components. Management in TINA is based on TMN and extended with ODP concepts, as TINA is not concerned with just network management, but also systems management. TINA management architecture addresses aspects of distribution, interoperability, dynamic manager/managed roles, and integration with service control functions. TINA service management concerns different activities of the service life-cycle, from four main aspects: access session management, service session management, user session management and communication session management. The TINA network resource model supports requirements from both network management activities and service connectivity needs.     

Robust stability constraints for fuzzy model predictive control

This paper addresses the synthesis of a predictive controller for a nonlinear process based on a fuzzy model of the Takagi-Sugeno (T-S) type, resulting in a stable closed-loop control system. Conditions are given that guarantee closed-loop robust asymptotic stability for open-loop bounded-input-bounded-output (BIBO) stable processes with an additive l₁-norm bounded model uncertainty. The idea is closely related to (small-gain-based) l₁-control theory, but due to the time-varying approach, the resulting robust stability constraints are less conservative. Therefore the fuzzy model is viewed as a linear time-varying system rather than a nonlinear one. The goal is to obtain constraints on the control signal and its increment that guarantee robust stability. Robust global asymptotic stability and offset-free reference tracking are guaranteed for asymptotically constant reference trajectories and disturbances     

Optimizing taxonomic semantic web queries using labeling schemes

This paper focuses on the optimization of the navigation through voluminous subsumption hierarchies of topics employed by portal catalogs like Netscape Open Directory (ODP). We advocate for the use of labeling schemes for modeling these hierarchies in order to efficiently answer queries such as subsumption check, descendants, ancestors or nearest common ancestor, which usually require costly transitive closure computations. We first give a qualitative comparison of three main families of schemes, namely bit vector, prefix and interval based schemes. We then show that two labeling schemes are good candidates for an efficient implementation of label querying using standard relational DBMS, namely the Dewey prefix scheme and an interval scheme by Agrawal et al. We compare their storage and query evaluation performance for the 16 ODP hierarchies using the PostgreSQL engine.     

A practical procedure for conceptual design and testing of machine tool structure

This paper discusses the initial development of a machine tool and its structure (concept, calculation, design) and the verification of the prototype. The topics studied include two issues: static rigidity and dynamic stability. For static rigidity several experiments and modelling studies using the finite element method have been carried out in order to identify the model parameters. In this way differences between models of bolted joints, slideways and the cross-section of the structural elements have been determined. The model is formed by design documentation and later verified through experiments on the prototype of the machine. The approach is different in the case of dynamic stability. The model is not made on the basis of design documentation or static calculations, but by experiments performed on the prototype. This relates to an oriented transfer function; parameters are determined by fitting experimental transfer function curves. With this model, the stability is analyzed under different machining conditions. Specific features of this methodology are as follows:

• • The finite element method is used for qualitative comparison of different machine tool structure concepts during the conceptual and design stages. Only after completion of the prototype may the parameters of the prototype model be adjusted for the purpose of obtaining quantitative indicators.

• • Dynamics are analyzed by parameter identification of the oriented transfer function model. The dominant degree of freedom is naturally selected by experiment and not from hypotheses about the behavior of structures obtained from mathematical manipulations such as expansion of the model according to the finite element method. If necessary another machine tool structure may be modelled; in this way hypotheses are drawn about the stability of the reconstructed prototype.

Such a procedure has been applied and verified on the machine tool structure of a horizontal machining center. Results for static rigidity and dynamic stability have been obtained from the model and experiments performed on the prototype. The following techniques have been used:

• • finite element method for qualitative identification of static behavior,

• • self-excitation of the machine,

• • digital signal processing on the FFT basis,

• • smoothing of curves and digital filtration,

• • function fitting of the transfer function (modal analysis),

• • coefficient calculus and oriented transfer function,

• • stability assessment of the fitted model under different machining conditions, and

• • modelling of the regenerative machining effect by cutting.

Necessary tests have been done by instruments required for the use of the above techniques.

Such a combined static-dynamic criteria procedure for structuring a machine tool enables efficient follow-up of all results and facilitates necessary future expansion, the utilization of universal equipment, the combination of modelling and experiments, and the synthesis of simple models of the examined machine with behavior identical to the machine. The well-known machining system dynamic stability theories are applied to such models.     

Preview tracking for discrete-time SISO systems

The preview tracking problem, that is, the problem of tracking a reference input when a window of its future values is known, is considered. This is done by showing how the set of all admissible regulated outputs of a system is modified when preview is incorporated. This allows the mechanism by which preview allows performance improvement to be seen more clearly . It also allows preview control systems to be designed using the powerful optimization techniques available for this framework. To exemplify this, some analytical results for the minimum l₁, l₂ and l_∞ norms of the tracking error in response to a step reference are derived for a simple system with preview. A worked example of some optimal compensator designs is also presented