The purpose of this thesis is to characterize, compare and contrast four network-centric software architectures, namely Client-Server Architecture (CSA), Distributed Objects Architecture (DOA), Service-Oriented Architecture (SOA) and Peer-to-Peer Architecture (PPA) and seven associated frameworks consisting of .NET, Java EE, CORBA, DCOM, Web Services, Jini and JXTA with respect to a set of derived criteria. Network-centric systems are gaining in popularity as they have the potential to solve more complex problems than we have been able to in the past. However, with the rise of SOA, Web Services, a set of standards widely used for implementing service-oriented solutions, is being touted as the "silver bullet" to all problems afflicting the software engineering domain with the danger of making other architectures seem obsolete. Thus, there is an urgent need to study the various architectures and frameworks in comparison to each other and understand their relative merits and demerits for building network-centric systems. The architectures studied here were selected on the basis of their fundamentality and generality. The frameworks were chosen on the basis of their popularity and representativeness to build solutions in a particular architecture. The criteria used for comparative assessment are derived from a combination of two approaches — by a close examination of the unique characteristics and requirements of network-centric systems and then by an examination of the constraints and mechanisms present in the architectures and frameworks under consideration that may contribute towards realizing the requirements of network-centric systems. Not all of the criteria are equally relevant for the architectures and frameworks. Some, when relevant, are relevant in a different sense from one architecture (or framework) to another. One of the conclusions that can be drawn from this study is that the different architectures are not completely different from each other. In fact, CSA, DOA and SOA are a natural evolution in that order and share several characteristics. At the same time, significant differences do exist, so it is clearly possible to judge/differentiate one from the other. All three architectures can coexist in a single system or system of systems. However, the advantages of each architecture become apparent only when they are used in their proper scope. At the same time, a sharp difference can be perceived between these three architectures and the peer-to-peer architecture. This is because PPA aims to solve a totally different class of problems than the other three architectures and hence has certain unique characteristics not observed in the others. Further, all of the frameworks have certain unique architectural features and mechanisms not found in the others that contribute towards achieving network-centric quality characteristics. The two broad frameworks, .NET and Java EE offer almost equivalent capabilities and features; what can be achieved in one can be achieved in the other. This thesis deals with the study of all the four architectures and their related frameworks. The criteria used, while fairly comprehensive, are not exhaustive. Variants of the fundamental architectures are not considered. However, system/software architects seeking an understanding of the tradeoffs involved in using the various architectures and frameworks and their subtle nuances should benefit considerably from this work. / Master of Science

International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Modem microcomputers are proving to be viable hosts for telemetry functions, including data simulators. A specialized high-performance hardware architecture for generating and processing simulator data can be implemented on an add-in card for the microcomputer. Support software implemented on the host provides a simple, high-quality human interface with a high degree of user programmability. Based on this strategy, the Physical Science Laboratory at New Mexico State University (PSL) is developing a Programmable PCM Data Simulator for microcomputer hosts. Specifications and hardware/software architectures for PSL’s Programmable PCM Data Simulator are discussed, as well as its interactive user interface.

Today it is more a rule than an exception that software systems have a lifecycle of more than several years. Hence, software evolution is inevitable. During the life span of a software system the domain in which the system is working evolves and changes. This causes changes to the software system, and the software system may also be evolved to satisfy new markets. The ability to evolve gracefully, and thus the long-term success of a software system, is to a large extent governed by its software architecture and the ability of the software architecture to fulfil requirements on quality attributes and to adapt to evolving requirements. In this thesis we study evolution of software architectures and what can be done to support this evolution. We focus on three particular aspects of evolution support: how to ensure that the correct blend of quality attributes is met (architecture selection), the technical means available for supporting changes in the software system (variability), and what types of changes that are likely to occur during evolution (categories of evolution). We introduce a method for architecture evaluation and selection that focus on ensuring that the selected software architecture is the architecture candidate with the most potential for fulfilling a particular blend of quality attributes. The method is based on quantification of expert opinions and focused discussions where these expert opinions differ. The architecture evaluation and selection method is studied in both an academic and in an industry setting. We also introduce a taxonomy of techniques for realising variability in a software system and study how the techniques in this taxonomy are applied in different evolution situations. The taxonomy is based on several industry case studies. Two industry cases are studied in further detail and the evolution of these systems are followed over a number of releases and generations. During this evolution it is shown how variability mechanisms are used to also support evolution, and that there are typical cases of evolution that a software system can be prepared to cope with. The contribution of this thesis is that it increases the understanding of how evolution occurs in a software system, how to create software that is flexible enough to support evolution and how to evaluate and select a software architecture that meets a particular blend of quality attributes. Together this ensures that a software system is based on a software architecture that fits the current quality requirements and that is flexible in the right places so that it is able to evolve gracefully.

Architecture Design for deploying or improving a tool or application is a vital step which should be neither ignored nor avoided. The architecture will provide the framework and instructions on how the tool needs to be created in order to comply with the stakeholders’ most important requirements. Utilizing data collected from the different stakeholders involved in the use of an existing tool, an effective architecture structure will be created to improve the tool and satisfy the users’ needs to achieve the desired goals in it. Through the use of an effective architecture design, a toolkit will be created to improve an existing Management Tool to provide a desired outcome. We have learned that having an architecture established prior to starting a development project or in the early lifecycle stages will positively influence the project’s outcome, timely deliverables and financial impact associated with it. It is crucial to consider all aspects surrounding a process or software design, such as stakeholder requirements, internal and external customer feedback, and any particular feature that will guarantee a reliable structure and deployment process. / text

<p>Over the past 20 years, the development in ComputationalElectromagnetics has produced a vast choice of methods based onthe large number of existing mathematical formulations of theMaxwell equations. None of them dominate over the others,instead they complement each other and the choice of methoddepends on the frequency range of the electromagnetic waves.This work is focused on the most popular method in the highfrequency scenario, namely the Geometrical Theory ofDiffraction (GTD). The main advantage of GTD is the ability topredict the electromagnetic field asymptotically in the limitof vanishing wavelength, when other methods, such as the Methodof Moments, become computationally too expensive.</p><p>The low cost of GTD is due to both the fact that there is noruntime penalty in increasing the frequency and that the raytracing, which GTD is based on, is a geometrical technique. Thecomplexity is then no longer dependent on electrical size ofthe problem but instead on geometrical sub problems which aremanageable. For industrial applications the geometricalstructures, with which the rays interact, are modelled bytrimmed Non-Uniform Rational B-Spline (NURBS) surfaces, themost recent standard used to represent complex free-formgeometries.</p><p>Due to the introduction of NURBS, the geometrical subproblems tend to be mathematically and numerically cumbersome,but they can be highly simplified by proper Object Orientedprogramming techniques. This allowed us to create a flexiblesoftware package, MIRA: Modular Implementation of Ray Tracingfor Antenna Applications, with an architecture that separatesmathematical algorithms from their implementation details andmodelling. In addition, its design supports hybridisationtechniques in combination with other methods such as Method ofMoment (MoM) and Physical Optics (PO).</p><p>In a first hybrid application, a triangle-based PO solveruses the shadowing information calculated with the ray tracerpart of MIRA. The occlusion is performed between triangles andtheir facing NURBS surfaces rather than between their facingtriangles, thus reducing the complexity. Then the shadowinginformation is used in an iterative MoM-PO process in order tocover higher frequencies, where the contribution of theshadowing effects, in the hybrid formulation, is believed to bemore significant.</p><p>Thesis presented at the Royal Institute of Technology ofStockholm in 2003, for the degree of Licentiate in ScientificComputing.</p>

The goal of this research is to validate the methodology used while investigating metrics directed verification of Unified Modeling Language (UML) based designs. This document is organized into five distinct sections. The topics discussed include an introduction to the UML, a discussion of available software metrics, a tutorial regarding the nature of design metrics, a discussion of available UML metrics, and the empirical study results. The empirical study presents detailed information regarding how UML class diagrams can be mapped to design metrics, a discussion on how the data was collected and verified, the results obtained during this study, what conclusions were drawn from the data, and recommendations for future research topics. Preliminary findings indicate that a correlation does exist between the external design complexity measure and the UML class diagrams. / Department of Computer Science

This thesis details the development and validation procedures of the experiment control software to be used on the NPSAT1. The software developed for a standard Linux kernel instead of an expensive proprietary space computer system includes functions for satellite orbit prediction, precise satellite location, and adaptive experiment scheduling using inputs from the electrical power system, sub-satellite position, and sub-satellite local time.

Approved for public release; distribution in unlimited. / The Department of Defense looks increasingly towards an interoperable and integrated system-of-systems to provide required military capability. Non-essential software complexity of a system-of-systems can have a greater negative impact in system behavior than a single system. Our current systems-of-systems tend to require a great deal of software maintenance and to be intolerant of even the most minor of changes with respect to negative perturbations in system behavior. In this thesis, we explore the benefits of developing a conceptual framework as the basis for the system-of-systems development. We examine the application of accepted software engineering practices for single-system developments to the more complex problem of system-of-systems development. Using the Ballistic Missile Defense System as a case study, we present an abstract framework from which we can reason about the system-of-systems. We develop a conceptual software architecture that represents a logical organization of proposed software modules. We map the functionality of the system to conceptual software components with coordination and data exchanges handled by conceptual connectors. Finally, we assess our work to determine the feasibility of applying the conceptual framework techniques described in this thesis to system-of-systems acquisitions with the objective of reducing accidental complexity and controlling essential complexity. / Civilian, Missile Defense Agency, Washington, D.C.

Os sistemas de televisão digital terrestre têm se estabelecido e expandido em várias regiões do mundo. A expectativa é de que 1,4 bilhão de televisores analógicas sejam substituídas por televisores e receptores digitais, também conhecidos como terminais de acesso. Daí a importância destes dispositivos que recebem e decodificam o sinal digital. Diante da diversidade de plataformas de hardware de diferentes fabricantes e perfis de terminais de acesso, existe a necessidade de um alto investimento para criar e desenvolver aplicações e software intermediário (Middleware) na medida em que existe a necessidade de diferentes códigos-fontes para cada uma das plataformas. Além desta fragmentação de implementações por conta das várias plataformas de hardware, existe a demanda crescente por desempenho e por soluções com um conjunto maior de funções. Para endereçar a estas questões, existem organizações, iniciativas e tecnologias emergentes em sistemas embarcados multimídia, algumas delas baseadas em componentes de software, que estão consolidando técnicas que podem ser aplicadas à estrutura de software de um terminal de acesso, dentre as quais destacamos a UHAPI, o M3W, o OpenMAX, a IOS e o GStreamer. Esta dissertação apresenta uma proposta de arquitetura de software denominada Arquimedia com base em uma análise comparativa destes trabalhos. Foram realizados e analisados ensaios de desempenho parciais para a validação da proposta. / The terrestrial digital television systems have been established and expanded by the worldwide. It is expected that 1.4 billion analog TV sets will be replaced by set-topboxes and digital receivers TV sets, also known as access terminals. This fact shows the relevance of these devices that receive and decode the digital signals. Given the diversity of the hardware platforms of different manufacturers and different set-topboxes profiles, there is a need for a major investment to create and develop applications and Middleware because for each hardware platform, different source codes need to be developed. Beside the fragmentation of implementations resulted by the diversity of hardware platforms, there is an increasing demand for performance and solutions with more functions. To address these questions, there are organizations, initiatives and emerging technologies, some of them based on software components, that are consolidating techniques that can be applied to the software stack of a set-top-box, from among we emphasize the UHAPI, M3W, IOS and GStreamer. This master thesis deals a comparative analysis of these technologies and presents a set-top-box software architecture proposal called Arquimedia. Performance tests were made and analyzed to validate the proposal.

A qualidade da arquitetura de software pode impactar diretamente a satisfação do usuário, uma vez que define se os atributos de qualidade serão atingidos, principalmente os requisitos não funcionais. Apesar disso, os conceitos de qualidade de arquitetura de software não são tratados com a devida importância pelos currículos dos cursos de graduação e pós-graduação dos cursos de Computação. A ausência de conhecimento sobre qualidade de arquitetura de software, dos trade-offs entre atributos de qualidade e de como medir esses atributos durante o ciclo de desenvolvimento de software faz com que egressos dos cursos de Computação somente aprendam que os atributos de qualidade de arquitetura são fatores crucias para o sucesso de um projeto da pior forma possível, ou seja, após muitos projetos fracassados em sua vida profissional, colocando em risco toda sua trajetória de carreira. Este trabalho de pesquisa propõe um método experimental (roteiro) para o ensino de qualidade de arquitetura de software guiado por atributos de qualidade, principalmente requisitos não funcionais, utilizando uma abordagem prática, iterativa e dirigida pelo processo de negócio com o objetivo de auxiliar no processo de aprendizagem da importância dos atributos de qualidade de arquitetura de software e medição desses atributos durante todo o ciclo de vida de um sistema. Para a elaboração do roteiro de ensino proposto foram utilizadas normas relacionadas à qualidade do produto e do processo de software, modelos de referência para sistemas de processamento distribuído, métodos de avaliação de arquiteturas de software e teorias pedagógicas relacionadas ao processo de ensino/aprendizagem. Para avaliação do roteiro de ensino proposto, o mesmo foi aplicado em disciplinas de graduação e pós-graduação em Engenharia de Computação, mais especificamente em disciplinas da área de Engenharia de Software. / The software architecture quality directly affects user satisfaction, since it defines if quality criteria will be achieved, especially regarding the non-functional requirements. However, software architecture quality concepts are not handled with due importance by undergraduate and graduate computer curricula. The lack of knowledge about software architecture quality, quality attribute trade-offs and how to measure these attributes during the software development cycle makes computer graduates/engineers only learn that software architecture quality is a key to a successful project in the worst way possible, i.e., after many failed projects in their professional lives, jeopardizing their entire career trajectory. This research proposes a experimental method (roadmap) for teaching software architecture quality guided by quality attributes, primarily by non-functional requirements, using an iterative and practical approach, driven by business process. This will help to teach the importance of software architecture quality and of measuring these attributes throughout the system life cycle. For developing the proposed roadmap, standards related to software product and process quality, reference models for distributed processing systems, methods for software architectures evaluation and pedagogical theories related to the learning process were used. To evaluate the proposed roadmap, it was applied in undergraduate and graduate Computer Engineering courses, specifically in Software Engineering disciplines.