Dissertations / Theses on the topic 'Software design'

Software engineering design is a vital component of modern industry, unfortunately, the processes involved are still poorly understood. This poses a major problem for teachers of the subject, who are under constant pressure to improve the quality of education, but are unsure how to bring this about, or even how to detect such improvement. This thesis attempts to start the process of clarifying what we mean by "software engineering design", and apply the insights gained to the activity of curriculum design. First, we establish a method for the research, by constructing a framework to constrain and guide the process of seeking new insights. This leads to a decidedly eclectic approach to the problem, as software engineering design is viewed, and reviewed, from a number of different perspectives. Next, these views are synthesised into a model of the software engineering design process, and new insights are sought to refine the model. The central theme of this model is the idea that the design process can be considered as a one of theory building. Finally, we bring this model into direct contact with the task of curriculum design, both in a general sense, and also by providing illustrations of some of the consequences of its use.

Software architecture design as an engineering field has evolved greatly during the last 15 years, which is evident by the number of methods, styles, patterns, and guidelines available for its practitioners in industry. This paper takes a closer look at the purposes behind this field to reveal the level of discrepancy in pursued purposes between industrial practitioners and published methods for software architecture design. In our research surveys of architecture design methods and of purposes at a number of industrial practitioners resulted in two sets of purposes which were eventually compared and the level of discrepancy identified.
Mjukvarudesign är ett område inom mjukvaruindustrin som utvecklats omfattande under de senaste 15 åren, vilket synliggjorts av de nya metoder, designstilar, designmönster och paradigmer som gjorts tillgängliga för mjukvaruutvecklare idag. Den här uppsatsen gör en djupgranskning av syftena bakom detta arbetsområde för att upptäcka eventuella skillnader mellan de syften som framhålls av befintliga arkitekturmetoder och de syften som åtsträvas av utövare inom mjukvaruindustrin.

Thesis (MScEng)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: The high pace of technological advancement enables the realisation of ever more advanced mobile communications standards with more functionality than simple voice communications. The hardware that is used to implement the radio sections of these systems generally require long design cycles, much longer than the design cycles of the other components of a communications system. Another problem is that, once new communications standards are introduced, the current hardware platforms used in the terminal equipment becomes obsolete because they can generally not be used with the new standards. This has serious cost implications for both the service provider and the consumer, because both parties have to acquire new equipment to be able to use the new standards. An elegant solution to the above issues is to use software-defined radio sections to replace the hardware radio components. New communications standards can then be supported by simply loading new software onto the equipment, provided the maximum processing capacity of the processor(s) that the software runs on can accommodate the bandwidth requirements of that specific standard. This thesis investigates the ideas behind software defined radio and also describes the design and implementation of a software architecture that can be used to implement software defined radios on general-purpose platforms such as personal computers.
AFRIKAANSE OPSOMMING: Die hoë tempo van tegnologiese vordering maak dit moontlik om baie gevorderde mobiele kommunikasie standaarde te implementeer wat meer funksionaliteit bied as blote spraakkommunikasie. Die hardeware wat gebruik word om die radios van sulke stelsels te implementeer neem gewoonlik langer om te ontwikkel as die ander komponente van die stelsels. Die ander probleem is dat hierdie hardeware gewoonlik nie hergebruik kan word wanneer nuwe kommunikasie standaarde in gebruik geneem word nie omdat die standaarde nie versoenbaar is nie. Dit het tot gevolg dat beide die verbruiker en die diensverskaffer groot bedrae geld moet spandeer om die nuwe tegnologie te kan gebruik. 'n Elegante oplossing vir hierdie probleme is om gebruik te maak van radios waarvan die funksionaliteit in sagteware gedefiniëer word. Nuwe kommunikasie standaarde kan dan gebruik word deur slegs die nodige sagteware op die toerusting te laai, solank die verwerkingskapasiteit van die mikroverwerkers in die stelsel die benodigde bandwydte kan akkommodeer. Hierdie tesis ondersoek die konsepte van sagteware-gedefiniëerde radio en beskryf die ontwerp en implementering van 'n sagteware argitektuur vir die implementering van sagteware-gedefiniëerde radios op veeldoelige platforms soos persoonlike rekenaars.

Software patterns provide solutions to recurring design problems, provide a way to reason about the quality attributes, and support stakeholders in understanding the system. Naturally, the use of software patterns emerges from the requirements of the software. Use Cases have been a traditional and authentic approach to document these requirements. We propose a way to mine these patterns by sing use cases and advocate their significance in saving resources and time. For this purpose, an open-source system is discussed and four design patterns are mined with the help of use cases elicited from the documentation and literature available for the selected system. Patterns mined in this system are then document in GOF format.Furthermore, the consequences of few patterns on quality attributes are studied and an additional design pattern is proposed to improve the quality of the system.
Folkspark Vägan 15:11 ,372 40 Ronneby ,Sweden

The development of simulation tools is becoming an important area in industry, recently fostered by the tremendous improvements in computer hardware. Many physical problems can be simulated by being modelled by mathematical equations which can then be solved numerically. This thesis is concerned with the development of a Finite Difference solver for time dependent partial differential equations. The development involves a number of challenging requirements that the solver must meet: to have the capacity of solving conservation and non-conservation laws (using several numerical techniques), to be robust, efficient and to have a modular and extendible design. Firstly, we focus on the architecture of the program and how an original design approach was used in order to carry out its development. A combination of Object- Oriented Design and Structured Design was adopted.

This dissertation comprises three essays on software design science, the philosophical, theoretical and empirical study of software creation and modification including its phenomenology, methodology and causality. The essays consider three limitations evident in the software design science literature: 1) lack of a precisely-defined, well-understood vocabulary; 2) difficulties surrounding empirical research; 3) lack of theory concerning the design process’s structure and organization. The first essay presents an extensive review of definitions of design, revealing nontrivial disagreements regarding its nature and scope. Following this, a formal definition of design and a conceptual model of design projects are constructed. The definition incorporates seven elements – agent, object, environment, goals, primitives, requirements and constraints. The conceptual model views design projects as temporal trajectories of work systems, in which human agents design systems for stakeholders, using resources and tools. This provides a detailed, defensible basis for theoretical and empirical software design science research. The second essay addresses the difficulties of empirical software design science research by elucidating a broad, bipolar conflict in design literature between two incompatible beliefs: 1) the belief that design is an innately cognitive, approximately rational, plan-centered activity (Reason-Centric Perspective); 2) the belief that design is an emergent phenomenon, improvised through continual interaction between agents and environments (Action-Centric Perspective). Each perspective is operationalized through a software design process theory: the Function-Behavior-Structure Framework (chosen for the Reason-Centric Perspective) and the Sensemaking-Coevolution-Implementation Framework (proposed for the Action-Centric Perspective). The third essay presents a survey study comparing these perspectives and theories. Responses from 1384 software development professionals in 65 countries indicate that the Sensemaking-Coevolution-Implementation Framework more accurately describes the structure and organization of their design processes than the Function-Behavior-Structure Framework. Gender, education, experience, nationality, occupation, team size, project duration, firm size, methodologies in use, and the nature of the software had no measurable effect on this finding. This supports a theory of the design process’s structure and organization and facilitates several streams of empirical research including studies of design project success.

1). After presenting an in depth analysis of the field of ontologies and software testing as conceived and implemented by the software engineering and artificial intelligence communities (chapter 2), we discuss an approach which enabled us to deploy ontologies in the early phases of software development (i.e.: specifications) in order to detect conceptual errors (chapter 3). It is based on the provision of ontological axioms which are used to verify conformance of specification constructs to the underpinning ontology. To facilitate the integration of ontology with applications that adopt it we developed an architecture and built tools to implement the this form of conceptual errors check (chapter 4). We apply and evaluate the architecture on a variety of contexts to identify potential uses (chapter 5). An implication of this method for deploying ontologies to reason about the correctness of applications is to raise our trust in given ontologies. However, when these are erroneous we might fail to reveal pernicious discrepancies. To cope with this problem we extended the architecture in a multi-layer form (chapter 4) which gives us the ability to check for correctness the ontologies themselves. We apply this multi-layer architecture to capture errors founded in a complex ontologies lattice (chapter 6). We further elaborate on the weaknesses in ontology evaluation methods and employed a technique stemming form software engineering, that of experience management, to facilitate ontology testing and deployment. (chapter 7). The work presented in this thesis aims to improve ontology exercise and identify areas to which ontologies could be of benefits other than the advocated ones of knowledge sharing and reuse (chapter 8).

International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California
Generalized telemetry data analysis systems have been developed to meet the future requirements for the analysis of telemetry data. By providing the user the freedom of stipulating the manner in which data is to be analyzed, the need for mission specific analysis software can be greatly reduced or eliminated entirely. Communications between the user and the software is accomplished by means of a user-software interface. Proper design of the interface will promote successful user-software communications. Interface design features such as menus and online documentation are discussed. Human engineering is an integral part of a successful user-software interface design. The human beings which operate the software possess limitations on their mental abilities and perception. Human engineering concepts which utilize display techniques and reference names are discussed. A definition of a successful user-software interface is given.

The development of simulation tools is becoming an important area in industry, recently fostered by the tremendous improvements in computer hardware. Many physical problems can be simulated by being modelled by mathematical equations which can then be solved numerically. This thesis is concerned with the development of a Finite Difference solver for time dependent partial differential equations. The development involves a number of challenging requirements that the solver must meet: to have the capacity of solving conservation and non-conservation laws (using several numerical techniques), to be robust, efficient and to have a modular and extendible design. Firstly, we focus on the architecture of the program and how an original design approach was used in order to carry out its development. A combination of Object- Oriented Design and Structured Design was adopted.

The aim of this thesis is to analyze a project to design and implement a new FM Radio application for Symbian OS. The project process and relevant events are discussed when they have an impact on the design work. The goal of the project was to offer an improved user experience with features like favorite stations, song history, RT+ support, and automatic region selection. In order to complete the application within the project schedule, the existing radio modules were to be reused as much as possible. The application was required to be developed using the Qt application framework and to have no dependencies on the old UI framework from the Symbian OS. Platform-independence, testability, and simplicity were other key requirements for the new radio application. A final comprehensive goal was to stick to established design patterns and to follow the design principles and good practices defined earlier in the bachelor’s thesis by the same author. An added challenge was provided by the necessity to develop the application on top of a new UI framework that was still in development itself. Constant changes to the framework put a strain on the already tight project schedule. The discussion focuses on the design of the engine module that was required to house most of the application logic. The engine is disconnected from the Symbian OS by the use of a wrapper module, whose purpose is to hide the platform details. Due to its relevance to the engine, the design of the wrapper is discussed in detail. The application UI and the reused radio modules are discussed briefly and only to the extent that is relevant for the engine design. The resulting design fulfills its requirements and the implemented application performs as designed. All the required features are supported, and the existing radio modules are reused. The lack of dependency on the old UI framework is witnessed by running the application in a system that does not contain the framework. The possibility to run the application on a Windows workstation also affirms that the platform-independence requirement was achieved. The design and implementation adhere to the principles outlined in the bachelor’s thesis and provide a practical use for them. The principles are found to be valid and important for the successful completion of a complex software project. It is discovered that the goal of designing a simple system from complicated beginnings is difficult to achieve and requires many iterations. Gradual refinements to the architecture and implementation are necessary to finally arrive at the optimal design. Constant refactoring is found to be a key element in the successful completion of a software project
Tässä työssä analysoidaan projektia, jossa suunniteltiin ja toteutettiin uusi FM Radio -sovellus Symbian-käyttöjärjestelmälle. Projektin prosessi ja oleelliset tapahtumat kuvataan siltä osin kuin ne vaikuttavat suunnittelutyöhön. Projektin tavoite oli tarjota parempi käyttökokemus uusilla ominaisuuksilla kuten suosikkikanavilla, kappalehistorialla, RT+ -tuella, ja automaattisella aluevalinnalla. Olemassa olevia radiomoduuleita oli uudelleenkäytettävä niin paljon kuin mahdollista, jotta projekti saataisiin aikataulun puitteissa valmiiksi. Sovellus tuli suunnitella Qt-sovelluskehystä käyttäen, eikä sillä saanut olla riippuvuuksia vanhaan käyttöliittymäkirjastoon. Alustariippumattomuus, testattavuus ja yksinkertaisuus olivat myös tärkeitä vaatimuksia. Viimeinen kattava tavoite oli pitäytyä vakiintuneissa suunnittelumalleissa ja noudattaa suunnitteluperiaatteita ja hyviä toimintatapoja, jotka olivat saman tekijän kandidaatintyössä aiemmin määritelty. Tarve toteuttaa sovellus keskeneräisen käyttöliittymäkirjaston päälle asetti oman lisähaasteensa. Jatkuvat muutokset kirjastossa rasittivat jo valmiiksi tiukkaa projektiaikataulua. Tämän työn pääpaino on moottorimoduulissa, jonka tuli sisältää suurin osa sovelluksen logiikasta. Moottori on eriytetty Symbian-käyttöjärjestelmästä adapterimoduulilla, jonka tarkoitus on piilottaa ohjelmistoalustan yksityiskohdat. Adapterin suunnitelma kuvataan yksityiskohtaisesti. Sovelluksen käyttöliittymä ja uudelleenkäytetyt radiomoduulit kuvataan lyhyesti ja vain niiltä osin kuin ne ovat moottorin suunnitelmalle oleellisia. Tuloksena syntyvä suunnitelma täyttää vaatimukset, ja toteutettu sovellus toimii kuten oli suunniteltu. Kaikki vaaditut ominaisuudet ovat tuettuja ja olemassa olevat radiomoduulit käytettiin uudelleen. Riippumattomuus vanhasta käyttöliittymäkirjastosta havaitaan suorittamalla sovellusta järjestelmässä, jossa sitä ei ole. Mahdollisuus ajaa sovellusta Windows-työasemassa myös todistaa sen, että alustariippumattomuuden vaatimus täytettiin. Suunnitelma ja toteutus noudattavat kandidaatintyössä määriteltyjä periaatteita ja tarjoavat niille käytännön sovellutuksen. Periaatteet todetaan paikkansapitäviksi ja tärkeiksi monimutkaisen ohjelmistoprojektin onnistuneen valmistumisen kannalta. Työssä havaitaan, että tavoite suunnitella yksinkertainen järjestelmä monimutkaisista lähtökohdista on vaikea saavuttaa ja vaatii useita toistoja. Asteittaiset korjaukset arkkitehtuuriin ja toteutukseen ovat välttämättömiä optimaaliseen suunnitelman saavuttamiseksi. Jatkuvan uudelleenjärjestelyn havaitaan olevan avainasemassa ohjelmistosuunnitteluprosessissa

Dissertation (Ph.D.) -- Worcester Polytechnic Institute.
Keywords: software engineering; inference; knowledge representation; software maintenance; design rationale. Includes bibliographical references (p. 202-211).

As the pace of business change increases, service-oriented (SO) solutions should facilitate easier maintainability as underlying business logic and rules change. To date, little effort has been dedicated to considering how the structural properties of coupling and cohesion may impact on the maintainability of SO software products. Moreover, due to the unique design characteristics of Service-Oriented Computing (SOC), existing Procedural and Object-Oriented (OO) software metrics are not sufficient for the accurate measurement of service-oriented design structures. This thesis makes a contribution to the field of SOC, and Software Engineering in general, by proposing and evaluating a suite of design-level coupling and cohesion metrics for predicting the maintainability of service-oriented software products early in the Software Development LifeCycle (SDLC). The proposed metrics can provide the following benefits: i) facilitate design decisions that could lead to the specification of quality SO designs that can be maintained more easily; ii) identify design problems that can potentially have a negative effect on the maintainability of existing service-oriented design structures; and iii) support more effective control of maintainability in the earlier stages of SDLC. More specifically, the following research was conducted as part of this thesis: - A formal mathematical model covering the structural and behavioural properties of service-oriented system design was specified. - Software metrics were defined in a precise, unambiguous, and formal manner using the above model. - The metrics were theoretically validated and empirically evaluated in order to determine the success of this thesis as follows: a. Theoretical validation was based on the property-based software engineering measurement framework. All the proposed metrics were deemed as theoretically valid. b. Empirical evaluation employed a controlled experimental study involving ten participants who performed a range of maintenance tasks on two SO systems developed (and measured using the proposed metrics) specifically for this study. The majority of the experimental outcomes compared favourably with our expectations and hypotheses. More specifically, the results indicated that most of the proposed metrics can be used to predict the maintainability of service-oriented software products early in the SDLC, thereby providing evidence for the validity and potential usefulness of the derived metrics. Nevertheless, a broader range of industrial scale experiments and analyses are required to fully demonstrate the practical applicability of the metrics. This has been left to future work.

In this thesis, effects of some software design patterns on real time software performance will be investigated. In real time systems, performance requirements are critical. Real time system developers usually use functional languages to meet the requirements. Using an object oriented language may be expected to reduce performance. However, if suitable software design patterns are applied carefully, the reduction in performance can be avoided. In this thesis, appropriate real time software performance metrics are selected and used to measure the performance of real time software systems.

Thesis (Ph.D) - Swinburne University of Technology, Faculty of Information & Communication Technologies, 2006.
"October 2006". Submitted in fulfillment of the requirements of for the degree of Doctor of Philosophy, Faculty of Information and Communication Technologies, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. [229]-237) and index.

Atualmente, novas metodologias de projeto são necessárias devido a crescente complexidade dos sistemas embarcados. Metodologias no nível de sistema são propostas para auxiliar o projetista a lidar com a crescente complexidade, iniciando o projeto em um nível de abstração mais alto que o nível de transferência de registradores. Ferramentas de estimativa de desempenho são uma importante parte das metodologias no nível de sistema, visto que as mesmas auxiliam a exploração do espaço de projeto desde os estágios iniciais. O objetivo desta tese é definir uma metodologia integrada para estimativa de desempenho do software. Atualmente, nota-se a crescente utilização de software embarcado, inclusive utilizando múltiplos processadores, visando atender os requisitos de flexibilidade, desempenho e potência consumida. O desenvolvimento de estimadores de desempenho de software não é trivial, devido à utilização de processadores embarcados com arquiteturas avançadas. Para auxiliar a seleção do processador no nível da especificação do sistema, um novo modelo de estimador do desempenho do software baseado em redes neurais é proposto. Redes neurais mostraram-se uma solução adequada para uma rápida estimativa de desempenho em um estágio inicial do projeto. Para realizar a análise do desempenho do software no nível funcional do barramento, onde o mapeamento do hardware e software já está definido, é utilizado um modelo global de simulação, chamado de protótipo virtual. A metodologia de análise de desempenho proposta neste trabalho é integrada a um ambiente para refinamento de interfaces de hardware e software chamada ROSES. A metodologia proposta é avaliada através de um estudo de caso de uma arquitetura multiprocessada de um codificador MPEG4.
Nowadays, embedded system complexity requires new design methodologies. System-level methodologies are proposed to cope with this complexity, starting the design above the register-transfer level. Performance estimation tools are an important piece of system-level design methodologies, since they are used to aid design space exploration at an early design stage. The goal of this thesis is to define an integrated methodology for software performance estimation. Currently, embedded software usage is increasing, becoming multiprocessor system-on-chip a common solution to cope with flexibility, performance, and power requirements. The development of accurate software performance estimators is not trivial, due to the increased complexity of embedded processors. To drive processor selection at specification level, a novel analytic software performance estimator based on neural networks is proposed. The neural network enables a fast estimation at an early design stage. To target the software performance analysis at bus functional level, where mapping of the hardware and software components is already established, we use a global simulation model supporting performance profiling. The proposed software performance estimation methodology is linked to a hardware and software interface refinement environment named ROSES. The proposed methodology is evaluated through a case study of a multiprocessor MPEG4 encoder.

For demanding applications, for example image or video processing, there may be computations that aren’t very suitable for digital signal processors. While a DSP processor is appropriate for some tasks, the instruction set could be extended in order to achieve higher performance for the tasks that such a processor normally isn’t actually design for. The platform used in this project is flexible in the sense that new hardware can be designed to speed up certain computations.

This thesis analyzes the computational complex parts of JPEG2000. In order to achieve sufficient performance for JPEG2000, there may be a need for hardware acceleration.

First, a JPEG2000 decoder was implemented for a DSP processor in assembler. When the firmware had been written, the cycle consumption of the parts was measured and estimated. From this analysis, the bottlenecks of the system were identified. Furthermore, new processor instructions are proposed that could be implemented for this system. Finally the performance improvements are estimated.

In this study, Window-based computer program, named Synthesis Software, is developed for designing filters with equal-ripple or maximally flat passbands and general stopbands by using cascade synthesis technique in transformed frequency domain. Synthesis technique is applicable to lumped element and commensurate line distributed element filters with Lowpass, Highpass or Bandpass characteristics. Singly or Doubly terminated filters can be synthesized. friendly environment for typing in the parameters of the filter to be designed. This part uses Synthesis and Plot parts as modules. This software is based on the previous softwares developed in EEE Department of Middle East Technical University. All the previous softwares were gathered in the well-known software Filpro, which is in DOS environment, in Pascal. Thus, the new software is actually a conversion of Synthesis part of Filpro from DOS environment into Windows environment in the language C#, with some improvements in root finding algorithms for numerical conditioning. Synthesis Software is has three parts. The first and main part is the implementation of synthesis technique by using object oriented programming technique. In this way, synthesis technique implementation is isolated from other parts of Synthesis Software and it can be used by other filter design programs as a module. The second part of the program is responseplotting section. In this part Insertion Loss, Return Loss, Time Delay, Phase and Smith Chart responses are calculated and displayed. The last part is User Interface, which provides user

The purpose of this thesis has been to convert two softwares called TPCAD (Three Phase Induction Machine Computer Aided Desing) and SPCAD (Single Phase Induction Machine Computer Aided Design) developed earlier for the design and analysis of three and single phase induction machines to meet the needs of motor manufacturing industry so that they can be run in windows environment. Furthermore, it was aimed to include features such as double cage motor analysis and design, to provide a facility designed motor lamination can be drawn for the user to see and facilitate sharing the designed lamination with other professional programs such as finite element analysis or thermal analysis etc. As a result of this study, a user friendly design tool facilitating the design process of induction motors has been upgraded by using C++ Microsoft Visual Studio .Net programming language. TPCAD and SPCAD are tested with different commercial motors. The results show that the full load performance calculations are within the range of 5% error for both programs. However, starting performance calculation errors are within 10% for TPCAD, and 8% for SPCAD.

This thesis presents an automated software design synthesis framework known as Project Calliope. This framework aligns with Harel's automated software development process as it addresses the aspect of automating design and implementation. Project Calliope is based on a Statecharts synthesis approach in the literature. The main goal of Project Calliope is to automatically generate testable Unified Modeling Language (UML) Statecharts that are deterministic, visually manageable and UML compliant. In order to minimise design errors in the generated UML Statecharts, Project Calliope supports model checking through Statecharts execution. In addition, executable code is automatically generated based on the synthesised UML Statecharts. This framework seeks to provide a pragmatic design framework that can be readily incorporated into software development methodologies that leverage UML. In this thesis, Project Calliope is applied to three simple applications from Whittle and Schumann's examples and a case study based on a commercial application. They are automatic teller machine, coffee dispenser, an agent application, and a groupware application respectively.

The Unified Modeling Language (UML) has become the standard language for the design of object-oriented software systems over the past decade. Even though there exist various tools which claim to support design with UML, their functionality is usually focused on drawing UML diagrams and generating code from the UML model. The task of choosing a suitable design which fulfils the requirements still has to be accomplished by the human designer alone. The aim of this thesis is to develop concepts for UML design tools which assist the modeller in improving the system design and requirements incrementally. For this approach a variant of formal games called exploration games is introduced as underlying technique. Exploration games can be defined on the basis of incomplete and imprecise UML models as they occur frequently in practice. The designer repeatedly plays an exploration game to detect flaws or incompleteness in the design and its specification, which are both incorporated in the game definition. At any time the game definition can be incremented by the modeller which allows him to react to the discoveries made during a play and experiment with new design solutions. Exploration games can be applied to UML in different variants. For each variant must be specified how the UML diagrams are used to set up the game and how the semantic variation points of UML should be interpreted. Furthermore some parts of the game definition may not be contained in the UML model and have to be provided separately. The emphasis of this thesis is on game variants which make use of UML diagrams for modelling system behaviour, especially state machines and activity diagrams. A prototypical implementation demonstrates how the concepts developed in this thesis can be put into practice. The tool supports the user in defining, playing and incrementing a game. Moreover it can compute winning strategies for the players and may act as opponent of the modeller. As example a game variant based on UML state machines has been implemented. The architecture that has been chosen for the tool leaves room for extension by additional game variants and alternative algorithms.

We propose a design by contract (DbC) approach to specify and maintain architectural level properties of software. Such properties are typically relevant in the design phase of the development cycle but may also impact the execution of systems. We give a formal framework for specifying software architectures (and their refi nements) together with contracts that architectural con figurations abide by. In our framework, we can specify that if an architecture guarantees a given pre- condition and a refi nement rule satisfi es a given contract, then the refi ned architecture will enjoy a given post-condition. Methodologically, we take Architectural Design Rewriting (ADR) as our architectural description language. ADR is a rule-based formal framework for modelling (the evolution of) software architectures. We equip the recon figuration rules of an ADR architecture with pre- and post-conditions expressed in a simple logic; a pre-condition constrains the applicability of a rule while a post-condition specifi es the properties expected of the resulting graphs. We give an algorithm to compute the weakest precondition out of a rule and its post-condition. Furthermore, we propose a monitoring mechanism for recording the evolution of systems after certain computations, maintaining the history in a tree-like structure. The hierarchical nature of ADR allows us to take full advantage of the tree-like structure of the monitoring mechanism. We exploit this mechanism to formally defi ne new rewriting mechanisms for ADR reconfi guration rules. Also, by monitoring the evolution we propose a way of identifying which part of a system has been a ffected when unexpected run-time behaviours emerge. Moreover, we propose a methodology that allows us to select which rules can be applied at the architectural level to reconfigure a system so to regain its architectural style when it becomes compromised by unexpected run-time recon figurations.

Software Engineering is one of the most widely researched areas of Computer Science. The ability to reuse software, much like reuse of hardware components is one of the key issues in software development. The object-oriented programming methodology is revolutionary in that it promotes software reusability. This thesis describes the development of a tool that helps programmers to design and implement software from within the Smalltalk Environment (an Object- Oriented programming environment). The ASDN tool is part of the PEREAM (Programming Environment for the Reuse and Evolution of Abstract Models) system, which advocates incremental development of software. The Asdn tool along with the PEREAM system seeks to enhance the Smalltalk programming environment by providing facilities for structured development of abstractions (concepts). It produces a document that describes the abstractions that are developed using this tool. The features of the ASDN tool are illustrated by an example.

L' architettura software è emersa come una importante tematica, nel campo del software engineering, per gestire la complessità relativa allo sviluppo e manutenzione di grandi sistemi software. L' idea chiave di questa tesi è che non c'è alcuna soluzione miracolosa nell' ambito del software engineering ma ogni tecnica ha i suoi vantaggi e svantaggi; di conseguenza, la bontà di un determinato metodo varia in base alle caratteristiche del contesto di applicazione. Un famoso proverbio dice: 1)un cattivo artigiano incolpa i suoi strumenti, 2) il peggior artigiano sceglie lo strumento sbagliato e poi da colpa allo strumento, 3) un buon artigiano sceglie ed usa gli strumenti in maniera opportuna. Mentre la comunità del software engineering si è occupata prevalentemente di offrire sempre nuovi metodi il cui utilizzo è supposto dare dei risultati migliori dei precedenti, c'è un vuoto nell' assistere l'architetto del sistema software nel selezionare o mettere a punto il giusto metodo. In questo contesto, la presente tesi offre un insieme di strumenti per la progettazione dell' architettura software, dal quale l' architetto di sistema è agevolato a selezione (e mettere appunto) il miglior strumento da utilizzare in base alle peculiarità del contesto di applicazione. Progettare una architettura software è un' attività molto complicata e involve differente tipologie di attività; la presente tesi riguarda le seguenti attività: metodi di progettazione dell' architettura software; tecniche decisionali per giungere a compromessi durane la progettazione dell' architettura software; strategie per applicare studi empirici sui metodi di progettazione architetturale; strategie di documentazioni delle decisioni progettuali
Software architecture has emerged as an important field of software engineering for managing the realm of large-system development and maintenance. The main intent of software architecture is to provide intellectual control over a sophisticated system enormous complexity. The key idea of this dissertation is that there is no silver bullet in software engineering, each method has pros and cons; the goodness of a method (tool, technique, etc.) varies based on the peculiarities of the application context. According to a famous idiom: i) a poor craftsman blames his tool, ii) a really bad craftsman chooses the wrong tool for the job and then he blames the tool, iii) a good craftsman chooses and uses the tool well. While the software engineering community has been mainly focused on providing new methods, which usage are aimed/supposed to provide better results than older methods, there is a lack in helping the software practitioners in selecting/adapting the available tools. Hence, in this view, the contribution of the present dissertation, instead of being a new method for architectural design, which would have been easily forgotten in a bookcase, is a characterization of the existing methods. In other words, this dissertation provides a toolbox for software architecture design, from which software architects can select the best method to apply, according to the application context. In this dissertation, the available architectural methods have been characterized by means of empirical studies. Unfortunately, the application of empirical methods on software architecture includes some troubles. A contribution of the present dissertation is a characterization of the available empirical methods by exposing their levels of challenges that researchers have to face when applying empiricism to software architecture. Such a proposed characterization should help to increase both the number and validity of software architecture empirical studies by allowing researchers to select the most suitable empirical method(s) to apply (i.e. the one with minor challenges), based on the application contexts (e.g. available software applications, architects, reviewers). However, in our view, in order to provide high levels of conclusion and internal validity, empirical methods for software architecture should be oriented to take advantage of both quantitative and qualitative data. Moreover, based on the results from two experiments, the challenges, in conducting evidence-based software architecture investigations, might 1) highly influence the results of the empirical studies, and 2) be faced by empiricistsâ cleverness. Architecting software system is a complex job and it encompasses several activities; this dissertation focuses on the following families of activities: software architecture design, resolving architectural tradeoffs, documenting design decisions, and enacting empirical studies on software architecture (as just described). Regarding the resolution of architectural tradeoffs, based on our review of already proposed decision making techniques, we realized that no one of the available decision-making technique can be considered in general better than another; each technique has intrinsically its own level of complexity and proneness to specific problems. Since we cannot decide in advance what degree of complexity of modeling is sufficient, instead of proceeding by trial and error, we offered guidelines on which complexity to emphasize for avoiding specific problem(s). Our key idea is to expose and organize in a useful way, namely by a characterization schema, in what extent each decision-making technique is prone to specific problems. In this way, the level of proneness of specific technique to specific problems becomes a quality attribute of the decision-making technique. Furthermore, we situated in the proposed characterization schema eighteen different decision-making techniques already proposed by the literature in the domains of architecture design, COTS selection, and release planning. Such localization validates the completeness of the proposed characterization schema, and it provides a useful reference for analyzing the state of the art Regarding software architecture design, this dissertation tried to answer to following question: " Do actual software architecture design methods meet architects needs?" To do so, we provide a characterization of the available methods by defining nine categories of software architectsâ needs, proposing an ordinal scale for evaluating the degree to which a given software architecture design method meets the needs, and then applying this to a set of software architecture design methods. Based on results from the present study, we argue that there are two opposite but valid answers to the aforementioned question: a) Yes, they do. In fact, we showed that one or more software architecture design methods are able to meet each individual architect needs that we considered. b) No, they do not. In fact, we showed that there is no software architecture design method that is able to meet any tuple of seven or more needs, which means that there is still some work to do to improve software architecture design methods to actually help architects. In order to provide directions for software architecture design method improvement, we presented couples of needs, and triplets of needs that actual software architecture design methods are unable to meet. Moreover, an architect can use such characterization to choose the software architecture design method which better meets his needs. Regarding design decision documentation, we conducted a controlled experiment for analyzing the impact of documenting design decisions rationale on effectiveness and efficiency of individual/team decision-making in presence of requirement changes. Main results show that, for both individual and team-based decision-making, effectiveness significantly improves, while efficiency remains unaltered, when decision-makers are allowed to use, rather not use, the proposed design rationale documentation technique. Being sure that documenting design-decisions rationale does help, we argued why it is not used in practice and what we can do to facilitate its usage. Older design decisions rationale documentation methods aimed at maximizing the consumer (documentation reader) benefits by forcing the producer (documentation writer) to document all the potential useful information; they eventually ran into too many inhibitors to be used in practice. In this dissertation we propose a value-based approach for documenting the reasons behind design decision, which is based on a priori understanding of who will benefit later on, from what set of information, and in which amount. Such a value-based approach for documenting the reasons behind design decision offers means to mitigate all the known inhibitors and it is based on the hypothesis that the set of required information depends on the purpose (use case) of the documentation. In order to validate such a hypothesis we ran an experiment in a controlled environment, employing fifty subjects, twenty-five decisions, and five different purposes (documentation use case) of the documentation. Each subjects practically used the documentation to enact all the five documentation use case(s) by providing an answer and a level of utility for each category of information in the provided documentation. Both descriptive and statistical results confirm our expectancies that the level of utility, related to the same category of information in the design decision rationale documentation, significantly changes according to the purpose of the documentation. Such result is novel and implies that the consumer of the rationale documentation requires, or not, a specific category of information according the specific purpose of the documentation. Consequently, empirical results suggest that the producer can tailor the design decision rationale documentation by including only the information required for the expected purposes of the documentation. This result demonstrates the feasibility of our proposed value-based approach for documenting the reasons behind design decision.

Software reuse can occur in various places during the software development cycle. Reuse of existing source code is the most commonly practiced form of software reuse. One of the key requirements for software reuse is readability, thus the interest in the use of data abstraction, inheritance, modularity, and aspects of the visible portion of module specifications. This research analyzed the contents of software reuse libraries to answer the basic question of what makes a good reusable software component. The approach taken was to measure and analyze various software metrics as mapped to design characteristics. A related research question investigated the change in the design principles over time. This was measured by comparing sets of Ada reuse libraries categorized into two time periods. It was discovered that recently developed Ada reuse components scored better on readability than earlier developed components. A benefit of this research has been the development of a set of "design for reuse" guidelines. These guidelines address coding practices as well as design principles for an Ada implementation. C++ software reuse libraries were also analyzed to determine if design principles can be applied in a language independent fashion. This research used cyclomatic complexity metrics, software science metrics, and traditional static code metrics to measure design features. This research provides at least three original contributions. First it collects empirical data about existing reuse libraries. Second, it develops a readability measure for software libraries which can aid in comparing libraries. And third, this research developed a set of coding and design guidelines for developers of reusable software. Future research can investigate how design principles for C++ change over time. Another topic for research is the investigation of systems employing reused components to determine which libraries are more successfully used than others.

Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, February 2004.
Includes bibliographical references (p. 114-116).
Background: Despite the identification of a "software crisis" in the 1960s, large software projects are full of defects even today [19]. These defects cause the software to behave unexpectedly. The cause generally is attributed to the inherent property of software to possess arbitrary complexity [20]. Additionally, computer software is becoming all pervading. There is literally an explosion of software automating things that were considered impossible to automate only a few years ago. Essentially, software is growing to encompass anything and everything with such speed that we don't have the time to reflect on 'what happens when the software does something that it was not intended to do?' In other words, the software encounters an anomaly or a defect something customers encounter everyday. In any case, whenever customers encounter problems caused by defects they need help to solve these problems. They generally seek such help at a software vendor's product support services. With software getting more and more complex it is getting extremely difficult to support customers in a timely and cost effective manner. There is a constant struggle to ensure high Quality of Service (QoS) with low Total Cost of Ownership (TCO), which in turn affects Return on Investment; in such a scenario considering nearly 80% of the costs associated with software occur after it is shipped to the customer. Currently, there are two solutions to such problems caused by defects: First, if the source of the problem itself is found to be a defect in the software then the software vendor generally fixes the problem by modifying their code. Such a problem is generally classified as a bug. By now it is known that software applications have such bugs or defects or anomalies. These bugs cause the software to behave unexpectedly. Depending on its severity this behavior can on one extreme go unnoticed or one the other end produce catastrophic results. It pervades all software whether it is the AT&T long distance switching node crash in 01/15/90, the well known Y2K bug in database related software, Microsoft Passport Security defect, Mars Polar Lander defect, or the Ariane 5 rocket defect. These are just a few examples of well known software bugs. For each well known bug there are untold numbers of bugs that may not see the limelight. These defects can arise due to many reasons during the design and development of the software however they primarily arise due the essence of software to possess inherent properties of complexity, conformity, changeability, and invisibility [20]. Hence, a question arises, "Do we still try to single-mindedly go for the elusory 0 bug product? OR Do we accept that there are going to be bugs and try incorporate / accommodate for this directly into the product or otherwise?" Second, if the source of the problem is such that the vendor cannot simply fix the product, then it is classified as a limitation of the software product itself. In such a case the support organization works with the customer to find a workaround. Additionally, if many customers encounter the same problem then the product needs to be modified based on the workarounds their support services have provided to customers. In other words the product evolves based on how its customers use it. Product support services also receive numerous problems that are non-defect related where the source could be customer error or ignorance, improper documentation etc and their solutions generally require end-user education and training, better documentation etc. However such nondefect related support incidences fall outside the scope of this thesis. In the defect related scenarios illustrated above most of the contemporary efforts to determine the root cause of a customer's problem, requires in-depth knowledge of the product, extensive debugging that is extremely tedious, painstaking, and manual. Resolution of a problem depends solely on the troubleshooting skills, experience and subjectivity of the Support Personal that the customer is able to get a hold of. Products have all along incorporated functionality such as better features, performance, scalability etc. into their designs however none explicitly addresses how to tackle a software application's problems. This is unfortunate since such problems deeply affect customers and software development organization alike. The former looses productivity, effectiveness, time and money while the latter expends dedicated monetary and human resources for troubleshooting software products for a number of years until the product is declared obsolete or the customer's license expires. Problems affect overall customer satisfaction with the software making them more skeptical of future releases. The bottom-line is that there is a strong need to innovate software design and development itself to address how to deal with software problems so that customers should not have to loose their time, money or their life because the software application they are using has problems.
by Prashant A. Shirolkar.
S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2006.
Includes bibliographical references (p. 88-92).
When people talk about software security, they usually refer to security applications such as antivirus software, firewalls and intrusion detection systems. There is little emphasis on the security in the software itself. Therefore the thesis sets out to investigate if we can develop secure software in the first place. It first starts with a survey of the software security field, including the definition of software security, its current state and the research having been carried out in this aspect. Then the development processes of two products known for their security: Microsoft IIS 6.0 and Apache HTTP Web Server are examined. Although their approaches to tackle security are seemingly quite different, the analysis and comparisons identify they share a common framework to address the software security problem - designing security early into the software development lifecycle. In the end the thesis gives recommendations as to how to design security into software development process based upon the principles from the research and the actual practices from the two cases. Finally it describes other remaining open issues in this field.
by Chang Tony Zhang.
S.M.

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.

Thesis (MScEng)-- Stellenbosch University, 2013.
ENGLISH ABSTRACT: A wide variety of design methodologies exist in literature and the methodologies employed may differ among companies and even among design teams. Therefore a software tool, called DiDeas II, is being developed for the early phases of mechanical engineering design. DiDeas II is customisable to accommodate various design methodologies. An approach for customisability which allows the user interface and data structure to be customised without changing the source code has been implemented in previous developments via an approach combining ontology and conceptual graphs. This approach is expanded in this thesis to allow for the implementation of various design methodologies through the use of tables for the display of information with inheritance of data among these tables. During groupwork, communication is both asynchronous and synchronous. DiDeas II has been developed in this thesis to facilitate and capture both asynchronous and synchronous communication between team members. Capturing such communications has the potential to provide insight into design decisions. The communication functionality was assessed in case studies in an academic environment. DiDeas II proved to be effective at recording “soft” information during design and placing the information into context for future reference. The degree to which DiDeas II could be customised to suit the design process at different companies was assessed through discussions with engineers in industry. These discussions showed that it was possible to customise DiDeas II according to the design processes followed by the participants.
AFRIKAANSE OPSOMMING: „n Wye verskeidenheid ontwerpsmetodologieë bestaan in die literatuur en die metodologieë wat gebruik word kan tussen maatskappye en selfs tussen ontwerpspanne verskil. Daarom word „n sagteware-hulpmiddel, genaamd DiDeas II, ontwikkel vir die vroeë fases van meganiese ingenieursontwerp. DiDeas II is pasbaar om voorsiening te maak vir verskeie ontwerpsmetodologieë. „n Benadering vir pasbaarheid wat toelaat dat die gebruikerskoppelvlak en datastruktuur aangepas kan word sonder om veranderings aan die bron-kode te maak, is geïmplementeer in vorige ontwikkelings deur „n benadering wat ontologie en konseptuele grafieke kombineer. Hierdie benadering is in hierdie tesis uitgebrei om voorsiening te maak vir die implementering van verskeie ontwerpsmetodologieë d.m.v. tabelle vir die vertoon van informasie, met data wat “oorgeërf” word tussen hierdie tabelle. Kommunikasie is beide asinkroon en sinkroon tydens groepwerk. DiDeas II is in hierdie tesis verder ontwikkel om beide asinkrone en sinkrone kommunikasie metodes te bemiddel en daarvan rekord te hou. Die rekordhouding van sulke kommunikasie het die potensiaal om insig te bied aangaande ontwerpbesluite. Die kommunikasie funksionaliteit is geassesseer in gevallestudies in „n akademiese omgewing. DiDeas II was effektief in die rekordhouding van “sagte” informasie tydens ontwerp, sowel as om sulke informasie binne konteks te plaas vir latere verwysing. Die mate waartoe DiDeas II aangepas kan word om voorsiening te maak vir die ontwerpsprosesse van verskillende maatskappye, is geassesseer deur gesprekke met ingenieurs in industrie. Hierdie gesprekke het getoon dat dit moontlik is om DiDeas II aan te pas volgens die ontwerpsprosesse wat die deelnemers gebruik.

Software systems are becoming inexorably more open, distributed, pervasive, mobile and connected. This thesis addresses the problem of how to build adaptive software systems. These systems need to reliably achieve system-level goals in volatile environments, where the system itself may be built from components of uncertain behaviour, and where the requirements for the software system may be changing. This thesis adopts the systemtheoretic concept of ontogenic adaptation from biology, and applies it to software architecture. Ontogenic adaptation is the ability of an individual system to maintain its organisational integrity by reconfiguring and regulating itself. A number of approaches to adaptive software architecture have been recently proposed that, to varying degrees, enable limited adaptive behaviour and reconfiguration, but none possess all the properties needed for ontogenic adaptation. We introduce a meta-model and framework called Role Oriented Adaptive Design (ROAD) that is consistent with the concept of maintaining organisational integrity through ontogenic adaptation. The ROAD meta-model defines software applications as networks of functional roles which are executed by players (objects, components, services, agents, people, or rolecomposites). These flexible organisational structures are adaptive because the relationships (contracts) between roles, and the bindings between roles and players, can be regulated and reconfigured at run-time. Such flexible organisational role-structures are encapsulated into composites each with its own organiser. Because self-managed composites are themselves role-players, these composites can be distributed and recursively composed. The organisers of the composites form a management system over which requirements and performance data pass. Rather than being monolithic constructions, ROAD software applications are dynamic, self-managed compositions of loosely-coupled, and potentially, distributed entities. The concepts in the ROAD meta-model have been implemented in a programming framework which can be extended by the application programmer to create adaptive applications. Central to this framework are dynamic contracts. These contracts define the role structure, control interactions between the role instances, and measure the performance of those interactions. Adaptivity is achieved by monitoring and manipulating these contracts, along with the role-player bindings. Contracts have been implemented using the mechanism of �association aspects�. The applicability of the ROAD framework to the domain of Service-Oriented Computing is demonstrated. The framework is further evaluated in terms of its ability to express the concept of ontogenic adaptation and also in terms of the overhead its runtime infrastructure imposes on interactions.

The Software Engineering Research Center (SERC) Design Metrics Research Team at Ball State University has developed a design metric D(G) of the form:D(G) = D~ + DiWhere De is the architectural design metric (external design metric) and D; is the detailed design metric (internal design metric).Questions to be investigated in this thesis are:Why can D, be an indicator of the potential error modules?Why can D; be an indicator of the potential error modules?Are there any significant factors that dominate the design metrics?In this thesis, the report of the STANFINS data is evaluated by using correlation analysis, regression analysis, and several other statistical techiques. The STANFINS study is chosen because it contains approximately 532 programs, 3,000 packages and 2,500,000 lines of Ada.The design metrics study was completed on 21 programs (approximately 24,000 lines of code) which were selected by CSC development teams. Error reports were also provided by CSC personnel.
Department of Computer Science