Context: There is an overwhelming prevalence of companies developing software in global software development (GSD) contexts. The existing body of knowledge, however, falls short of providing comprehensive empirical evidence on the implication of GSD contexts on software quality for evolving software systems. Therefore there is limited evidence to support practitioners that need to make informed decisions about ongoing or future GSD projects. Objective: This thesis work seeks to explore changes in quality, as well as to gather confounding factors that influence quality, for software systems that evolve in GSD contexts. Method: The research work in this thesis includes empirical work that was performed through exploratory case studies. This involved analysis of quantitative data consisting of defects as an indicator for quality, and measures that capture software evolution, and qualitative data from company documentations, interviews, focus group meetings, and questionnaires. An extensive literature review was also performed to gather information that was used to support the empirical investigations. Results: Offshoring software development work, to a location that has employees with limited or no prior experience with the software product, as observed in software transfers, can have a negative impact on quality. Engaging in long periods of distributed development with an offshore site and eventually handing over all responsibilities to the offshore site can be an alternative to software transfers. This approach can alleviate a negative effect on quality. Finally, the studies highlight the importance of taking into account the GSD context when investigating quality for software that is developed in globally distributed environments. This helps with making valid inferences about the development settings in GSD projects in relation to quality. Conclusion: The empirical work presented in this thesis can be useful input for practitioners that are planning to develop software in globally distributed environments. For example, the insights on confounding factors or mitigation practices that are linked to quality in the empirical studies can be used as input to support decision-making processes when planning similar GSD projects. Consequently, lessons learned from the empirical investigations were used to formulate a method, GSD-QuID, for investigating quality using defects for evolving systems. The method is expected to help researchers avoid making incorrect inferences about the implications of GSD contexts on quality for evolving software systems, when using defects as a quality indicator. This in turn will benefit practitioners that need the information to make informed decisions for software that is developed in similar circumstances.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a PC-based Advanced Telemetry Processing and Display System (ATPDS)- a highend, real-time telemetry processing and display system implemented on a COTS PC platform. for A network-centric architecture was chosen from candidate architectures as the most viable for the ATPDS. The network-centric architecture is Windows NT-based, client/server based, supporting clients and servers on both local or remote PC workstations. The architecture supports distributing processing loads across multiple workstations, optimizing mission processing requirements. The advantage of this system is its flexibility and expandability with low acquisition and life-cycle support costs. The ATPDS allows the user to configure one or more small systems into a larger high-end system based on varying mission requirements.

published_or_final_version / Computer Science and Information Systems / Doctoral / Doctor of Philosophy

Computational reflection is a fundamental mechanism in object oriented languages. Reflection has proved useful in many contexts, such as in the design of development environments, language extension, and the dynamic, unanticipated adaptation of running systems We identify three problems with the current approach to reflection in object oriented languages: partial behavioral reflection needs to be anticipated, structural reflection is limited to the granularity of a method, and behavioral reflection cannot be applied to the whole system. To address these problems, we extend structural reflection to cover sub-method elements and present how sub-method structural reflection supports unanticipated partial behavioral reflection. We add the concept of context to represent meta-level execution and show how this allows behavioral reflection to be applied even to system classes. We describe an implementation in Smalltalk. Benchmarks validate the practicability of our approach. In addition, we present an experimental evaluation in which we show how the system is used for dynamic analysis. We realize dynamic feature analysis by annotating the sub-method structure of the system directly to denote features instead of recording full execution traces.

<p>The human enters into the information age in 21st century; the computer science and technology are developed at full speed, and already infiltrate into various field extensively. Resultantly manual drawing gradually is phased out, for those designers who have no prior experience in the computer operation are concerned, they need to have a kind of two-dimensional graphical tool. Graphics editor system arose to the request for designing planar figures for people who have little knowledge in computer.</p><p>This paper describes the development process of this system what is studied for the foundation, utilize object-oriented method to analyze, design with computer figure, and adopt Visual C ++ 6.0 as the developing platform. All these have been finished after 1 month or so. It designs to be two-dimensional graphical software with diverse function which operates simply, easy to study, mutual interface friendly graphics editor system and has satisfied some figure users at present with the new demand as well.</p><p>The following main functions have been realized in this application: It can draw various figures, such as dot, line, circle, arc, parabola and curve, modify them and comprehensive editing. Figure editor includes translation, mirroring, rotating and some similar operations. Comprehensive drawing includes drawing polygon (sealed and arbitrary polygon), round tangent line, round circle contact, line circle contact, some circle contacts and so forth. Meanwhile obtain the point of intersect between the arbitrary crossing, and draw different figures basically according to the points of intersect. By the way, it is capable to cancel and redraw the editing.</p>

Industrial-scale software is commonly very large and complex, making it difficult and time-consuming to develop. In order to manage complexity in software, developers break systems into smaller components which can be developed independently. Software contracts were first proposed several decades ago; they are used to explicitly specify the interfaces between software components to ensure that they work together correctly. Software contracts specify both the responsibility of a client using a service and of the component providing the service. The advantage of contracts is that they formalise what constitutes correct interactions between software components. In addition, they serve as documentation, as well as a basis for test cases, and help clarify correct use of inheritance. However, despite their usefulness, software contracts are still not widely used in mainstream software engineering. In this work, we aim to develop a new software contract tool which we hope will help increase the use of software contracts. We start our work by evaluating existing software contract technologies and uncover a range of inconsistencies and shortcomings. We find that there are disagreements surrounding even some of the most basic aspects of software contracts. Using the lessons learned from our analysis of existing tools, we design a new contract tool, PACT. We describe in detail the formal semantics and typing of PACT and develop a first implementation of our tool. Finally, we discuss the advantages of PACT over existing tools, including its rigorous separation of interfaces and implementations, its rich inheritance semantics, and its support for flexible and expressive definition of contracts.

The design of a new computer language, called the User Interface Language (UIL), is analyzed and evaluated by coding a representative procedure. UIL will provide the man-machine interface for command procedures on the Space Station FREEDOM. The UIL procedure written is modeled after an operational procedure used in the Space Shuttle program. This work provides a concrete test case to verify that UIL can be used to implement procedures for the Space Station. The object oriented approach taken with UIL is based on the successful application of these concepts for a variety of other software tools in operation today. Three major enhancements are proposed in this thesis: event handlers, data structures, and class/object creation capabilities. The addition of these capabilities changes the character of UIL from an object manipulation language to an object based language. The new capabilities, if adopted, will profoundly change the future of UIL.

The goal of this research is to realize the advantages of declarative modeling for complex physical systems that involve both advection and diffusion to varying degrees in multiple domains. This occurs, for example, in chemical devices such as fuel cells. The declarative or equation-based modeling approach can provide computational advantages and is compatible with physics-based, object-oriented representations. However, there is no generally accepted method of representing coupled advection and diffusion in a declarative modeling framework. This work develops, justifies, and implements a new upstream discretization scheme for mixed advective and diffusive flows that is well-suited for declarative models. The discretization scheme yields a gradual transition from pure diffusion to pure advection without switching events or nonlinear systems of equations. Transport equations are established in a manner that ensures the conservation of material, momentum, and energy at each interface and in each control volume. The approach is multi-dimensional and resolved down to the species level, with conservation equations for each species in each phase. The framework is applicable to solids, liquids, gases, and charged particles. Interactions among species are described as exchange processes which are diffusive if the interaction is inert or advective if it involves chemical reactions or phase change. The equations are implemented in a highly modular and reconfigurable manner using the Modelica language. A wide range of examples are demonstrated—from basic models of electrical conduction and evaporation to a comprehensive model of a proton exchange membrane fuel cell (PEMFC). Several versions of the PEMFC model are simulated under various conditions including polarization tests and a cyclical electrical load. The model is shown to describe processes such as electro-osmotic drag and liquid pore saturation. It can be scaled in complexity from 4000 to 32,000 equations, resulting in a simulation times from 0.2 to 19 s depending on the level of detail. The most complex example is a seven-layer cell with six segments along the length of the channel. The model library is thoroughly documented and made available as a free, open-source software package.

Reuse of software designs, experience and components is essential to making substantial improvements in software productivity, development cost, and quality. However, the many facets of reuse are still rarely used in the various phases of the software development lifecycle because of a lack of adequate theories, processes, and tools to support consistent application of reuse concepts. There is a need for approaches including definitions, models and properties of reuse that would provide explicit guidance to a software development team in applying reuse. In particular there is a need to provide abstractions that clearly separate the various functional concerns addressed in a software system. Separating concerns simplifies the identification of the software components that can benefit from reuse and can provide guidance on how reuse may be applied. In this thesis we present an extended model related to the separation of concerns in object-oriented design. The model, called views, indicates how an object-oriented design can be clearly separated into objects and their corresponding interfaces. In this model objects can be designed so that they are independent of their environment, because adaptation to the environment is the responsibility of the interface or view. The view can be seen as expressing the semantics for the 'glue' that joins components or objects together to create a software system. Informal versions of the views model have already been successfully applied to operational and commercial software systems. The objective of this thesis is to provide the views notion with a theoretical foundation to address reuse and separation of concerns. After clearly defining the views model we show the formal approach to combining the objects, interfaces (views), and their interconnection into a complete software system. The objects and interfaces are defined using an object calculus based on temporal logic, while the interconnections among object and views are specified using category theory. This formal framework provides the mathematical foundation to support the verification of the properties of both the components and the composite software system. We then show how verification can be mechanized by converting the formal version of the views model into higher-order logic and using PVS to support mechanical proofs.

This thesis considers the phenomenological experience of e-reading (reading on an electronic screen) as a way-in to discussing wider issues of technology and our encounter with objects in our environments. By considering the resistance shown toward reading on iPads and Kindles in popular and academic discourse as a source of valuable “folk phenomenological” report, this thesis hopes to shed light on both the particular engagement of portable e-reading and the general experience of embodied encounters with artefacts. The first chapter will consider the shortcomings of contemporary definitions of technology and aims to provide its own definition commensurate to the task of describing the intimate and very human encounter with equipment, an encounter which will be described as “technological.” In the second chapter an ontology (begun in the background of the first) will be developed which primarily considers our encounter with things that are as embodied as ourselves. This ontology sees evolution as an epistemological concern, with every evolutionary act occurring as a response to environmental pressures and producing a knowledge of that environment. This knowledge, it will be argued, in light of conclusions drawn from an engagement with Object Oriented Ontology, can be tested only via repeatable successful action with that which might be known. Such evolutionary concerns, it will be further argued, are equally applicable to our artefacts. The third chapter will focus on metaphor and critical theory to consider how e-reading in particular might function as a material metaphor, enabling productive thought. It will conclude with readings of three texts which put the language of all three chapters to work. This thesis draws on several fields, including Critical Theory, Cognitive Neuroscience, Evolutionary Epistemology, and Philosophy, the bringing together of which is intended to be of use to the still emerging Digital Humanities and the work's home discipline of English Studies as it gets used to the substantial alterations in the substrate of its object of study.