Refactoring object-z specifications

Object-Z offers an object-oriented means for structuring formal specifications. We investigate the application of refactoring rules to add and remove structure from such specifications to forge object-oriented designs. This allows us to tractably move from an abstract functional description of a system toward a lower-level design suitable for implementation on an object-oriented platform.

An object-orient designed FDTD simulator: Applications to high field systems

An object-oriented finite-difference time-domain (FDTD) simulator has been developed for electromagnetic study and design applications in Magnetic Resonance Imaging. It is aimed to be a complete FDTD model of an MRI system including all high and low-frequency field generating units and electrical models of the patient. The design method is described and MRI-based numerical examples are presented to illustrate the function of the numerical solver, particular emphasis is placed on high field studies.

Animation of object-z specifications using a Z animator

We discuss a methodology for animating the Object-Z specification language using a Z animation environment. Central to the process is the introduction of a framework to handle dynamic instantiation of objects and management of object references. Particular focus is placed upon building the animation environment through pre-existing tools, and a case study is presented that implements the proposed framework using a shallow encoding in the Possum Z animator. The animation of Object-Z using Z is both automated and made transparent to the user through the use of a software tool named O-zone.

A methodology for analysis and control of discrete event dynamic systems

The rapid developments in computer technology have resulted in a widespread use of discrete event dynamic systems (DEDSs). This type of system is complex because it exhibits properties such as concurrency, conflict and non-determinism. It is therefore important to model and analyse such systems before implementation to ensure safe, deadlock free and optimal operation. This thesis investigates current modelling techniques and describes Petri net theory in more detail. It reviews top down, bottom up and hybrid Petri net synthesis techniques that are used to model large systems and introduces on object oriented methodology to enable modelling of larger and more complex systems. Designs obtained by this methodology are modular, easy to understand and allow re-use of designs. Control is the next logical step in the design process. This thesis reviews recent developments in control DEDSs and investigates the use of Petri nets in the design of supervisory controllers. The scheduling of exclusive use of resources is investigated and an efficient Petri net based scheduling algorithm is designed and a re-configurable controller is proposed. To enable the analysis and control of large and complex DEDSs, an object oriented C++ software tool kit was developed and used to implement a Petri net analysis tool, Petri net scheduling and control algorithms. Finally, the methodology was applied to two industrial DEDSs: a prototype can sorting machine developed by Eurotherm Controls Ltd., and a semiconductor testing plant belonging to SGS Thomson Microelectronics Ltd.

Reconfigurable service-oriented architecture for autonomic computing

Almost a decade has passed since the objectives and benefits of autonomic computing were stated, yet even the latest system designs and deployments exhibit only limited and isolated elements of autonomic functionality. In previous work, we identified several of the key challenges behind this delay in the adoption of autonomic solutions, and proposed a generic framework for the development of autonomic computing systems that overcomes these challenges. In this article, we describe how existing technologies and standards can be used to realise our autonomic computing framework, and present its implementation as a service-oriented architecture. We show how this implementation employs a combination of automated code generation, model-based and object-oriented development techniques to ensure that the framework can be used to add autonomic capabilities to systems whose characteristics are unknown until runtime. We then use our framework to develop two autonomic solutions for the allocation of server capacity to services of different priorities and variable workloads, thus illustrating its application in the context of a typical data-centre resource management problem.

The design of a support department simulator for use in the design of manufacturing systems

Manufacturing firms are driven by competitive pressures to continually improve the effectiveness and efficiency of their organisations. For this reason, manufacturing engineers often implement changes to existing processes, or design new production facilities, with the expectation of making further gains in manufacturing system performance. This thesis relates to how the likely outcome of this type of decision should be predicted prior to its implementation. The thesis argues that since manufacturing systems must also interact with many other parts of an organisation, the expected performance improvements can often be significantly hampered by constraints that arise elsewhere in the business. As a result, decision-makers should attempt to predict just how well a proposed design will perform when these other factors, or 'support departments', are taken into consideration. However, the thesis also demonstrates that, in practice, where quantitative analysis is used to evaluate design decisions, the analysis model invariably ignores the potential impact of support functions on a system's overall performance. A more comprehensive modelling approach is therefore required. A study of how various business functions interact establishes that to properly represent the kind of delays that give rise to support department constraints, a model should actually portray the dynamic and stochastic behaviour of entities in both the manufacturing and non-manufacturing aspects of a business. This implies that computer simulation be used to model design decisions but current simulation software does not provide a sufficient range of functionality to enable the behaviour of all of these entities to be represented in this way. The main objective of the research has therefore been the development of a new simulator that will overcome limitations of existing software and so enable decision-makers to conduct a more holistic evaluation of design decisions. It is argued that the application of object-oriented techniques offers a potentially better way of fulfilling both the functional and ease-of-use issues relating to development of the new simulator. An object-oriented analysis and design of the system, called WBS/Office, are therefore presented that extends to modelling a firm's administrative and other support activities in the context of the manufacturing system design process. A particularly novel feature of the design is the ability for decision-makers to model how a firm's specific information and document processing requirements might hamper shop-floor performance. The simulator is primarily intended for modelling make-to-order batch manufacturing systems and the thesis presents example models created using a working version of WBS/Office that demonstrate the feasibility of using the system to analyse manufacturing system designs in this way.

Teallach - a flexible user - interface development environment for object database applications

The Teallach project has adapted model-based user-interface development techniques to the systematic creation of user-interfaces for object-oriented database applications. Model-based approaches aim to provide designers with a more principled approach to user-interface development using a variety of underlying models, and tools which manipulate these models. Here we present the results of the Teallach project, describing the tools developed and the flexible design method supported. Distinctive features of the Teallach system include provision of database-specific constructs, comprehensive facilities for relating the different models, and support for a flexible design method in which models can be constructed and related by designers in different orders and in different ways, to suit their particular design rationales. The system then creates the desired user-interface as an independent, fully functional Java application, with automatically generated help facilities.

Managing conflict in user-oriented development environments: Effects on information systems success

Today, many organizations are turning to new approaches to building and maintaining information systems (I/S) to cope with a highly competitive business environment. Current anecdotal evidence indicates that the approaches being used improve the effectiveness of software development by encouraging active user participation throughout the development process. Unfortunately, very little is known about how the use of such approaches enhances the ability of team members to develop I/S that are responsive to changing business conditions.^ Drawing from predominant theories of organizational conflict, this study develops and tests a model of conflict among members of a development team. The model proposes that development approaches provide the relevant context conditioning the management and resolution of conflict in software development which, in turn, are crucial for the success of the development process.^ Empirical testing of the model was conducted using data collected through a combination of interviews with I/S executives and surveys of team members and business users at nine organizations. Results of path analysis provide support for the model's main prediction that integrative conflict management and distributive conflict management can contribute to I/S success by influencing differently the manifestation and resolution of conflict in software development. Further, analyses of variance indicate that object-oriented development, when compared to rapid and structured development, appears to produce the lowest levels of conflict management, conflict resolution, and I/S success.^ The proposed model and findings suggest academic implications for understanding the effects of different conflict management behaviors on software development outcomes, and practical implications for better managing the software development process, especially in user-oriented development environments. ^

An aspect-oriented approach to designing role-based access control services

Access control (AC) limits access to the resources of a system only to authorized entities. Given that information systems today are increasingly interconnected, AC is extremely important. The implementation of an AC service is a complicated task. Yet the requirements to an AC service vary a lot. Accordingly, the design of an AC service should be flexible and extensible in order to save development effort and time. Unfortunately, with conventional object-oriented techniques, when an extension has not been anticipated at the design time, the modification incurred by the extension is often invasive. Invasive changes destroy design modularity, further deteriorate design extensibility, and even worse, they reduce product reliability. ^ A concern is crosscutting if it spans multiple object-oriented classes. It was identified that invasive changes were due to the crosscutting nature of most unplanned extensions. To overcome this problem, an aspect-oriented design approach for AC services was proposed, as aspect-oriented techniques could effectively encapsulate crosscutting concerns. The proposed approach was applied to develop an AC framework that supported role-based access control model. In the framework, the core role-based access control mechanism is given in an object-oriented design, while each extension is captured as an aspect. The resulting framework is well-modularized, flexible, and most importantly, supports noninvasive adaptation. ^ In addition, a process to formalize the aspect-oriented design was described. The purpose is to provide high assurance for AC services. Object-Z was used to specify the static structure and Predicate/Transition net was used to model the dynamic behavior. Object-Z was extended to facilitate specification in an aspect-oriented style. The process of formal modeling helps designers to enhance their understanding of the design, hence to detect problems. Furthermore, the specification can be mathematically verified. This provides confidence that the design is correct. It was illustrated through an example that the model was ready for formal analysis. ^

The object binary interface: C++ objects for evolvable shared class libraries

Object-oriented design and object-oriented languages support the development of independent software components such as class libraries. When using such components, versioning becomes a key issue. While various ad-hoc techniques and coding idioms have been used to provide versioning, all of these techniques have deficiencies - ambiguity, the necessity of recompilation or re-coding, or the loss of binary compatibility of programs. Components from different software vendors are versioned at different times. Maintaining compatibility between versions must be consciously engineered. New technologies such as distributed objects further complicate libraries by requiring multiple implementations of a type simultaneously in a program. This paper describes a new C++ object model called the Shared Object Model for C++ users and a new implementation model called the Object Binary Interface for C++ implementors. These techniques provide a mechanism for allowing multiple implementations of an object in a program. Early analysis of this approach has shown it to have performance broadly comparable to conventional implementations.

An aspect-oriented framework for orthogonal persistence

The life cycle of software applications in general is very short and with extreme volatile requirements. Within these conditions programmers need development tools and techniques with an extreme level of productivity. We consider the code reuse as the most prominent approach to solve that problem. Our proposal uses the advantages provided by the Aspect-Oriented Programming in order to build a reusable framework capable to turn both programmer and application oblivious as far as data persistence is concerned, thus avoiding the need to write any line of code about that concern. Besides the benefits to productivity, the software quality increases. This paper describes the actual state of the art, identifying the main challenge to build a complete and reusable framework for Orthogonal Persistence in concurrent environments with support for transactions. The present work also includes a successfully developed prototype of that framework, capable of freeing the programmer of implementing any read or write data operations. This prototype is supported by an object oriented database and, in the future, will also use a relational database and have support for transactions.

Delivery Of A Urology Online Course Using Moodle Versus Didactic Lectures Methods.

To subjectively and objectively compare an accessible interactive electronic library using Moodle with lectures for urology teaching of medical students. Forty consecutive fourth-year medical students and one urology teacher were exposed to two teaching methods (4 weeks each) in the form of problem-based learning: - lectures and - student-centered group discussion based on Moodle (modular object-oriented dynamic learning environment) full time online delivered (24/7) with video surgeries, electronic urology cases and additional basic principles of the disease process. All 40 students completed the study. While 30% were moderately dissatisfied with their current knowledge base, online learning course delivery using Moodle was considered superior to the lectures by 86% of the students. The study found the following observations: (1) the increment in learning grades ranged from 7.0 to 9.7 for students in the online Moodle course compared to 4.0-9.6 to didactic lectures; (2) the self-reported student involvement in the online course was characterized as large by over 60%; (3) the teacher-student interaction was described as very frequent (50%) and moderately frequent (50%); and (4) more inquiries and requisitions by students as well as peer assisting were observed from the students using the Moodle platform. The Moodle platform is feasible and effective, enthusing medical students to learn, improving immersion in the urology clinical rotation and encouraging the spontaneous peer assisted learning. Future studies should expand objective evaluations of knowledge acquisition and retention.

Formal derivation of finite state machines for class testing

Previous work on generating state machines for the purpose of class testing has not been formally based. There has also been work on deriving state machines from formal specifications for testing non-object-oriented software. We build on this work by presenting a method for deriving a state machine for testing purposes from a formal specification of the class under test. We also show how the resulting state machine can be used as the basis for a test suite developed and executed using an existing framework for class testing. To derive the state machine, we identify the states and possible interactions of the operations of the class under test. The Test Template Framework is used to formally derive the states from the Object-Z specification of the class under test. The transitions of the finite state machine are calculated from the derived states and the class's operations. The formally derived finite state machine is transformed to a ClassBench testgraph, which is used as input to the ClassBench framework to test a C++ implementation of the class. The method is illustrated using a simple bounded queue example.

Lattice-dome design using a knowledge-based system approach

In the design of lattice domes, design engineers need expertise in areas such as configuration processing, nonlinear analysis, and optimization. These are extensive numerical, iterative, and lime-consuming processes that are prone to error without an integrated design tool. This article presents the application of a knowledge-based system in solving lattice-dome design problems. An operational prototype knowledge-based system, LADOME, has been developed by employing the combined knowledge representation approach, which uses rules, procedural methods, and an object-oriented blackboard concept. The system's objective is to assist engineers in lattice-dome design by integrating all design tasks into a single computer-aided environment with implementation of the knowledge-based system approach. For system verification, results from design examples are presented.

Expert system application on preliminary design of water retaining structures

Design of liquid retaining structures involves many decisions to be made by the designer based on rules of thumb, heuristics, judgment, code of practice and previous experience. Various design parameters to be chosen include configuration, material, loading, etc. A novice engineer may face many difficulties in the design process. Recent developments in artificial intelligence and emerging field of knowledge-based system (KBS) have made widespread applications in different fields. However, no attempt has been made to apply this intelligent system to the design of liquid retaining structures. The objective of this study is, thus, to develop a KBS that has the ability to assist engineers in the preliminary design of liquid retaining structures. Moreover, it can provide expert advice to the user in selection of design criteria, design parameters and optimum configuration based on minimum cost. The development of a prototype KBS for the design of liquid retaining structures (LIQUID), using blackboard architecture with hybrid knowledge representation techniques including production rule system and object-oriented approach, is presented in this paper. An expert system shell, Visual Rule Studio, is employed to facilitate the development of this prototype system. (C) 2002 Elsevier Science Ltd. All rights reserved.