EOS: A project to investigate the design and construction of real-time distributed embedded operating systems

The EOS project is investigating the design and construction of a family of real-time distributed embedded operating systems for reliable, distributed aerospace applications. Using the real-time programming techniques developed in co-operation with NASA in earlier research, the project staff is building a kernel for a multiple processor networked system. The first six months of the grant included a study of scheduling in an object-oriented system, the design philosophy of the kernel, and the architectural overview of the operating system. In this report, the operating system and kernel concepts are described. An environment for the experiments has been built and several of the key concepts of the system have been prototyped. The kernel and operating system is intended to support future experimental studies in multiprocessing, load-balancing, routing, software fault-tolerance, distributed data base design, and real-time processing

Real-time system design using preemption thresholds

As the real-time embedded systems encountered in applications such as telecommunications, aerospace, defense, and automatic control demand large, complex and multi-tasked software development, a new challenge has emerged for adopting the state-of-the-art software engineering technologies. Object-oriented design provides a scalable methodology with appropriate CASE tools for the design of software systems. Although these tools provides support for visual object-oriented modeling, design, simulation and code generation for general real-time systems, timing analysis is only available after the software is constructed. Consequently, the design-development process involving these tools in real-time systems becomes iterative and time-consuming. Introducing timing analysis in the design stage encounters a new problem. Traditional scheduling theory assumes a single level of task granularity. However, in industrial practice, common wisdom requires several design level tasks map into one run-time thread to reduce scheduling costs. This warrants a dual-level scheduling: preemptive scheduling between threads and non-preemptive scheduling between tasks in the same thread. Extending the scheduling theory to such an environment forms the scope of this thesis. Preemption threshold is introduced to control undesirable preemptions. Via a novel application of this concept, this thesis proposes a general scheduling model that subsumes both preemptive and non-preemptive scheduling models as special cases. The new theory deals with both independent and dependent tasks derivable from an object-oriented system model. Motivated by UML-RT modeling, the dependencies in our model include inter-task communication, resource sharing, and precedence. Important design issues covered include task priority and preemption threshold assignment and optimized task to thread mapping with respect of minimum scheduling cost and memory requirement. Quantitative performance evaluation is also conducted via simulation to validate the theory propose

Strategy Design Pattern

Design patterns usually describe abstract systems of interaction between classes, objects, and communication flows. So, a description of a set of interacting classes that provide a generalized solution framework to a generalized/specific design problem in a specific context can be said as a design pattern. There are many design patterns that can be used to solve real-life problems, but it remains very difficult to design, implement and reuse software for complex applications. Examples of these include enterprise system, real-time market data monitoring and analysis system. Design patterns provide an efficient way to create more flexible, elegant and ultimately reusable object-oriented software. Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice201D;. The solutions of the given problems are expressed in terms of objects and interfaces. Among 23 design patterns, Strategy pattern defines an interface common to all supported algorithms. Context uses this interface to call the algorithm defined by a Concrete Strategy. In accounting framework one thing is mostly needed that is tax calculation. To solve this problem author in the current study has chosen the strategy pattern

Making intelligent systems team players. A guide to developing intelligent monitoring systems

This reference guide for developers of intelligent monitoring systems is based on lessons learned by developers of the DEcision Support SYstem (DESSY), an expert system that monitors Space Shuttle telemetry data in real time. DESSY makes inferences about commands, state transitions, and simple failures. It performs failure detection rather than in-depth failure diagnostics. A listing of rules from DESSY and cue cards from DESSY subsystems are included to give the development community a better understanding of the selected model system. The G-2 programming tool used in developing DESSY provides an object-oriented, rule-based environment, but many of the principles in use here can be applied to any type of monitoring intelligent system. The step-by-step instructions and examples given for each stage of development are in G-2, but can be used with other development tools. This guide first defines the authors' concept of real-time monitoring systems, then tells prospective developers how to determine system requirements, how to build the system through a combined design/development process, and how to solve problems involved in working with real-time data. It explains the relationships among operational prototyping, software evolution, and the user interface. It also explains methods of testing, verification, and validation. It includes suggestions for preparing reference documentation and training users

Software Development for Manufacturing Systems- Language and Networking Issues

We have witnessed unprecedented changes in the industrial world with the advent of computers and the field of manufacturing is no exception. With the boom of microcomputers, th eir usage in manufacturing systems was realized at every level- from the shop floor level to the administrative and management layers. This paper deals with the software development issues that a software engineer has to take into account when analyzing, designing, and implementing software for manufacturing systems. Two important criteria that one has to consider are the real-time requirements and the device indepemdent abstractions that such software has to provide to the end-user, since it is reasonable to expect an end-user to know very little about the software intricacies. Two specific aspects of manufaturing software are discussed indetail here. The first part discusses a language with an object oriented flavor for programming manufacturing systems. In particular, some of the design aspects and implementation issues are discussed. The other part describes the networking issues that are specific ot the manufaturing environment. A prototype manufacturing system developed as a part of the p roject is used as a model to explain the various concepts and issues. A detailed description of the new language, Cell Programing Language (CPL), developed for the prototype is also included

Two Case Studies of Subsystem Design for General-Purpose CSCW Software Architectures

This paper discusses subsystem design guidelines for the software architecture of general-purpose computer supported cooperative work systems, i.e., systems that are designed to be applicable in various application areas requiring explicit collaboration support. In our opinion, guidelines for subsystem level design are rarely given most guidelines currently given apply to the programming language level. We extract guidelines from a case study of the redesign and extension of an advanced commercial workflow management system and place them into the context of existing software engineering research. The guidelines are then validated against the design decisions made in the construction of a widely used web-based groupware system. Our approach is based on the well-known distinction between essential (logical) and physical architectures. We show how essential architecture design can be based on a direct mapping of abstract functional concepts as found in general-purpose systems to modules in the essential architecture. The essential architecture is next mapped to a physical architecture by applying software clustering and replication to achieve the required distribution and performance characteristics

Embedding object-oriented design in system engineering

The Unified Modeling Language (UML) is a collection of techniques intended to document design decisions about software. This contrasts with systems engineering approaches such as for exampleStatemate and the Yourdon Systems Method (YSM), in which the design of an entire system consisting of software and hardware can be documented. The difference between the system- and the software level is reflected in differences between execution semantics as well as in methodology. In this paper, I show how the UML can be used as a system-level design technique. I give a conceptual framework for engineering design that accommodates the system- as well as the software level and show how techniques from the UML and YSM can be classified within this framework, and how this allows a coherent use of these techniques in a system engineering approach. These ideas are illustrated by a case study in which software for a compact dynamic bus station is designed. Finally, I discuss the consequences of this approach for a semantics of UML constructs that would be appropriate for system-level design

Communications software performance prediction

Software development can be costly and it is important that confidence in a software system be established as early as possible in the design process. Where the software supports communication services, it is essential that the resultant system will operate within certain performance constraints (e.g. response time). This paper gives an overview of work in progress on a collaborative project sponsored by BT which aims to offer performance predictions at an early stage in the software design process. The Permabase architecture enables object-oriented software designs to be combined with descriptions of the network configuration and workload as a basis for the input to a simulation model which can predict aspects of the performance of the system. The prototype implementation of the architecture uses a combination of linked design and simulation tools

Internet enabled modelling of extended manufacturing enterprises using the process based techniques

The paper presents the preliminary results of an ongoing research project on Internet enabled process-based modelling of extended manufacturing enterprises. It is proposed to apply the Open System Architecture for CIM (CIMOSA) modelling framework alongside with object-oriented Petri Net models of enterprise processes and object-oriented techniques for extended enterprises modelling. The main features of the proposed approach are described and some components discussed. Elementary examples of object-oriented Petri Net implementation and real-time visualisation are presented

Simulation of complex environments:the Fuzzy Cognitive Agent

The world is becoming increasingly competitive by the action of liberalised national and global markets. In parallel these markets have become increasingly complex making it difficult for participants to optimise their trading actions. In response, many differing computer simulation techniques have been investigated to develop either a deeper understanding of these evolving markets or to create effective system support tools. In this paper we report our efforts to develop a novel simulation platform using fuzzy cognitive agents (FCA). Our approach encapsulates fuzzy cognitive maps (FCM) generated on the Matlab Simulink platform within commercially available agent software. We firstly present our implementation of Matlab Simulink FCMs and then show how such FCMs can be integrated within a conceptual FCA architecture. Finally we report on our efforts to realise an FCA by the integration of a Matlab Simulink based FCM with the Jack Intelligent Agent Toolkit