Connection Management in Reconfigurable Distributed Systems

The Programmer\u27s Playground takes a new approach to simplifying and supporting the construction of distributed applications. The approach, called I/O abstraction, separates the description of a system\u27s communication structure from the descriptions of its computational components so that software modules written in existing programming languages cna be integrated flexibly and dynamically by both programmers and end-users. This separation is achieved by estabishing logical connectinos among the data interfaces of independent software modules. The logical connections provide a uniform high-level view of communication for both discrete and continuous data. The I/O abstraction approach inherits ideas from the I/O automaton model, a formal model of distributed computing that provides compositionality properties and supports behavioral specifications of system modules. Implications of I/O abstraction for process migration and the ordering of events in a distributed system will be studied. Software supporting the I/O abstraction programming model will be constructed. A high speed ATM network developed at Washington University will be used as a testbed for the devlopment work. The availability of this campus network offers an unusual opportunity to construct novel distributed (multimedia) applications and to test our ideas in realistic settings. The connection management network protocol (CMNP), the underlying protocol for the ATM networks, will be formally studied by giving a formal specification

Enhancing Federated Cloud Management with an Integrated Service Monitoring Approach

Cloud Computing enables the construction and the provisioning of virtualized service-based applications in a simple and cost effective outsourcing to dynamic service environments. Cloud Federations envisage a distributed, heterogeneous environment consisting of various cloud infrastructures by aggregating different IaaS provider capabilities coming from both the commercial and the academic area. In this paper, we introduce a federated cloud management solution that operates the federation through utilizing cloud-brokers for various IaaS providers. In order to enable an enhanced provider selection and inter-cloud service executions, an integrated monitoring approach is proposed which is capable of measuring the availability and reliability of the provisioned services in different providers. To this end, a minimal metric monitoring service has been designed and used together with a service monitoring solution to measure cloud performance. The transparent and cost effective operation on commercial clouds and the capability to simultaneously monitor both private and public clouds were the major design goals of this integrated cloud monitoring approach. Finally, the evaluation of our proposed solution is presented on different private IaaS systems participating in federations. © 2013 Springer Science+Business Media Dordrecht

Fail-Safe Testing of Safety-Critical Systems

This dissertation proposes an approach for testing of safety-critical systems. It is based on a behavioral and a fault model. The two models are analyzed for compatibility and necessary changes are identified to make them compatible. Then transformation rules are used to transform the fault model into the same model type as the behavioral model. Integration rules define how to combine them. This approach results in an integrated model which then can be used to generate tests using a variety of testing criteria. The dissertation illustrates this general framework using a CEFSM for the behavioral model and a Fault Tree for the fault model. We apply the technique to a variety of applications such as a Gas burner, an Aerospace Launch System, and a Railroad Crossing Control System. We also investigate the scalability of the approach and compare its efficiency with integrating a state chart and a fault tree. Construction and Analysis of Distributed Processes (CADP) has been used as a supporting tool for this approach to generate test cases from the integrated model and to analyze the integrated model for some properties such as deadlock and livelock

Semantic Grid Technologies in Computer Integrated Construction

Important goal of computer science in civil engineering projects is to facilitate dynamic collaboration among the companies, improvements of services and reuse of programs, data, information and knowledge. Civil engineering has some specific requirements concerning computer applications, which arise from the irrepeatability and scale of particular civil engineering products, processes and collaborating groups. Internet technologies are basis for linking processes in all construction phases, which leads to computer integrated construction. Computing grid, or shortly grid is a service infrastructure, which is being developed to facilitate infinite and seamless sharing of widely distributed, heterogeneous resources, hence, contributing towards the solution of complex engineering problems. A hypothesis of this work is that the grid can become viable platform for computer integrated construction, if semantic technologies are used for its development, i.e. ontologies and metadata, information, ontology and resource broker grid services. The hypothesis is tested by developing an ontology that defines the concept of a grid resource to describe specific resources in a grid environment. The aforementioned grid services are included in the design of a grid system, and are developed and deployed in a test bed. The test bed allows for the execution of complex grid applications, which take the form of workflows. It is shown that the ontology and the metadata about grid resources are useful when enabling, discovering, selecting and dynamically integrating resources on the grid. This approach yields several improvements against existing systems: a higher level of abstraction when developing and executing innovative and powerful engineering applications, greater flexibility, resource utilization and security, which is very important for dynamic collaboration within virtual organizations

Preference modelling approaches based on cumulative functions using simulation with applications

In decision making problems under uncertainty, Mean Variance Model (MVM) consistent with Expected Utility Theory (EUT) plays an important role in ranking preferences for various alternative options. Despite its wide use, this model is appropriate only when random variables representing the alternative options are normally distributed and the utility function to be maximized is quadratic; both are undesirable properties to be satisfied with actual applications. In this research, a novel methodology has been adopted in developing generalized models that can reduce the deficiency of the existing models to solve large-scale decision problems, along with applications to real-world disputes. More specifically, for eliciting preferences for pairs of alternative options, two approaches are developed: one is based on Mean Variance Model (MVM), which is consistent with Expected Utility Theory (EUT), and the second is based on Analytic Hierarchy Processes (AHP). The main innovation in the first approach is in reformulating MVM to be based on cumulative functions using simulation. Two models under this approach are introduced: the first deals with ranking preferences for pairs of lotteries/options with non-negative outcomes only while the second, which is for risk modelling, is a risk-preference model that concerns normalized lotteries representing risk factors each is obtained from a multiplication decomposition of a lottery into its mean multiplied by a risk factor. Both approximation models, which are preference-based using the determined values for expected utility, have the potential to accommodate various distribution functions with different utility functions and capable of handling decision problems especially those encountered in financial economics. The study then reformulates the second approach, AHP; a new algorithm, using simulation, introduces an approximation method that restricts the level of inherent uncertainty to a certain limit. The research further focuses on proposing an integrated preference-based AHP model introducing a novel approximation stepwise algorithm that combines the two modified approaches, namely MVM and AHP; it multiplies the determined value for expected utility, which results from implementing the modified MVM, by the one obtained from processing AHP to obtain an aggregated weight indicator. The new integrated weight scale represents an accurate and flexible tool that can be employed efficiently to solve decision making problems for possible scenarios that concern financial economics Finally, to illustrate how the integrated model can be used as a practical methodology to solve real life selection problems, this research explores the first empirical case study on Tender Selection Process (TSP) in Kurdistan Region (KR) of Iraq; it is considered as an inductive and a comprehensive investigation on TSP, which has received minimum consideration in the region, and regarded as a significant contribution to this research. The implementation of the proposed model to this case study shows that, for the evaluation of construction tenders, the integrated approach is an appropriate model, which can be easily modified to assume specific conditions of the proposed project. Using simulation, generated data allows creation of a feedback system that can be utilized for the evaluation of future projects in addition to its capability to make data handling easier and the evaluation process less complex and time consuming

An investigation into a distributed virtual reality environment for real-time collaborative 4D construction planning and simulation

The use and application of 4 Dimensional Computer Aided Design (4D CAD) is growing within the construction industry. 4D approaches have been the focus of many research efforts within the last decade and several commercial tools now exist for the creation of construction simulations using 4D approaches. However, there are several key limitations to the current approaches. For example, 4D models are normally developed after the initial planning of a project has taken place using more traditional techniques such as Critical Path Method (CPM). Furthermore, mainstream methodologies for planning are based on individual facets of the construction process developed by discrete contractors or sub-contractors. Any 4D models generated from these data are often used to verify work flows and identify problems that may arise, either in terms of work methods or sequencing issues. Subsequently, it is perceived that current 4D CAD approaches provide a planning review mechanism rather than a platform for a novel integrated approach to construction planning. The work undertaken in this study seeks to address these issues through the application of a distributed virtual reality (VR) environment for collaborative 4D based construction planning. The key advances lie in catering for geographically dispersed planning by discrete construction teams. By leveraging networked 4D-VR based technologies, multidisciplinary planners, in different places, can be connected to collaboratively perform planning and create an integrated and robust construction schedule leading to a complete 4D CAD simulation. Establishing such a complex environment faces both technological and social challenges. Technological challenges arise from the integration of traditional and recent 4D approaches for construction planning with an ad hoc application platform of VR linked through networked computing. Social challenges arise from social dynamics and human behaviours when utilizing VR-based applications for collaborative work. An appropriate 4D-based planning method in a networked VR based environment is the key to gaining a technical advancement and this approach to distributed collaborative planning tends to promote computer-supported collaborative work (CSCW). Subsequently, probing suitable CSCW design and user interface/interaction (UI) design are imperative for solutions to achieve successful applicability. Based on the foregoing, this study developed a novel robust 4D planning approach for networked construction planning. The new method of interactive definition was devised through theoretical analysis of human-computer interaction (HCI) studies, a comparison of existing 4D CAD creation, and 3D model based construction planning. It was created to support not only individual planners’ work but multidisciplinary planners’ collaboration, and lead to interactive and dynamic development of a 4D simulation. From a social perspective, the method clarified and highlighted relevant CSCW design to enhance collaboration. Applying this rationale, the study specified and implemented a distributed groupware solution for collaborative 4D construction planning. Based on a developed system architecture, application mode and dataflow, as well as a real-time data exchange protocol, a prototype system entitled ‘4DX’ was implemented which provides a platform for distributed multidisciplinary planners to perform real-time collaborative 4D construction planning. The implemented toolkit targeted a semi-immersive VR platform for enhanced usability with compatibility of desktop VR. For the purpose of obtaining optimal UI design of this kind of VR solution, the research implemented a new user-centred design (UCD) framework of Taguchi-Compliant User-Centred Design (TC-UCD) by adapting and adopting the Taguchi philosophy and current UCD framework. As a result, a series of UIs of the VR-based solution for multifactor usability evaluation and optimization were developed leading to a VR-based solution with optimal UIs. The final distributed VR solution was validated in a truly geographically dispersed condition. Findings from the verification testing, the validation, and the feedback from construction professionals proved positive in addition to providing constructive suggestions to further reinforce the applicability of the approach in the future.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Can Component/Service-Based Systems Be Proved Correct?

Component-oriented and service-oriented approaches have gained a strong enthusiasm in industries and academia with a particular interest for service-oriented approaches. A component is a software entity with given functionalities, made available by a provider, and used to build other application within which it is integrated. The service concept and its use in web-based application development have a huge impact on reuse practices. Accordingly a considerable part of software architectures is influenced; these architectures are moving towards service-oriented architectures. Therefore applications (re)use services that are available elsewhere and many applications interact, without knowing each other, using services available via service servers and their published interfaces and functionalities. Industries propose, through various consortium, languages, technologies and standards. More academic works are also undertaken concerning semantics and formalisation of components and service-based systems. We consider here both streams of works in order to raise research concerns that will help in building quality software. Are there new challenging problems with respect to service-based software construction? Besides, what are the links and the advances compared to distributed systems?Comment: 16 page

Industry-driven innovative system development for the construction industry: The DIVERCITY project

Collaborative working has become possible using the innovative integrated systems in construction as many activities are performed globally with stakeholders situated in various locations. The Integrated VR based information systems can bind the fragmentation and provide communication and collaboration between the distributed stakeholders n various locations. The development of these technologies is vital for the uptake of these systems by the construction industry. This paper starts by emphasising the importance of construction IT research and reviews some future research directions in this area. In particular, the paper explores how virtual prototyping can improve the productivity and effectiveness of construction projects, and presents DIVERCITY, which is th as a case study of the research in virtual prototyping. Besides, the paper explores the requirements engineering of the DIVERCITY project. DIVERCITY has large and evolving requirements, which considered the perspectives of multiple stakeholders, such as clients, architects and contractors. However, practitioners are often unsure of the detail of how virtual environments would support the construction process, and how to overcome some barriers to the introduction of new technologies. This complicates the requirements engineering process