Nas últimas décadas a tecnologia de realidade virtual tem sido cada vez mais utilizada em várias aplicações na sociedade. Particularmente a partir do início da década de 90, observamos o advento da realidade virtual baseada em multiprojeções, com o surgimento do paradigma de construção de sistemas de realidade virtual totalmente imersivos como por exemplo o CAVE™. Esta tese tem por objetivo apresentar pesquisas e desenvolvimentos relacionados com a implementação do primeiro sistema de multiprojeção totalmente imersivo baseado em aglomerado de computadores convencionais, sistema este denominado de CAVERNA Digital. O trabalho aqui apresentado é composto por um panorama atual do estado da arte das tecnologias de realidade virtual baseadas em multiprojeção. O conceito de aglomerados de computadores convencionais para realidade virtual, ou especificamente VRCluster é apresentado, bem como uma taxonomia de organização interna dos VRClusters. O sistema de multiprojeção da CAVERNA Digital é apresentado, descrevendo em detalhe as opções dos inúmeros subsistemas como projetores, telas, subsistema de vídeo, dispositivos de interação e outros. Outra contribuição desta tese é pela inovação de uma plataforma de visualização interativa voltada para ambientes de realidade virtual imersivos, plataforma esta denominada de JINX, baseada no padrão aberto X3D. Aspectos relacionados com a operação destes sistemas de realidade virtual avançados são apresentados como é o caso das interface de gerenciamento de ambientes imersivos denominado de SIRIUS e do núcleo de gerenciamento de ambientes imersivos denominado de ZEUS. Por fim vários testes de desempenho são realizados para a validação da integração dos inúmeros recursos utilizados na CAVERNA Digital. / In the last decades, virtual reality technology has been increasingly used in many applications for the society. Particularly in the beginning of 90’s, we can observe the advent of virtual reality based in multi-projections, leading to the construction paradigm of CAVE™ like virtual reality systems. The goal of this thesis is to present the research and developments related to the construction of the first multi projection completely immersive system based on commodity computer clusters called CAVERNA Digital. The work here presented is composed by an updated panorama of the state-of-art multi-projection virtual reality technologies. The concept of commodity computer clusters for virtual reality, or specifically VRCluster is shown, as well as the taxonomy for internal organization of the VRClusters. The CAVERNA Digital multi-projection system is shown, including details of the options of uncountable subsystems, like projectors, screens, video, and interaction devices, among others. This thesis contributes with another innovation: the visualization platform, called JINX, based on the open standard X3D. Aspects related to the operation of these advanced virtual reality systems are presented, which is the case of the user interface for immersive environments called SIRIUS and the management core for immersive environments called ZEUS. Finally, various performance tests were conducted to validate the integration of the uncountable resources used in the CAVERNA Digital.

Three of the most widely studied software dependency types are the structural, logical and semantic dependencies. Logical dependencies capture the degree of co-change between software artifacts. Semantic dependencies capture the degree to which artifacts, comments and names are related. Structural dependencies capture the dependencies in the source code of artifacts. Prior studies show that a combination of dependency analysis (e.g., semantic and logical analysis) improves accuracy when predicting which artifacts are likely to be impacted by ripple effects of software changes (though not to a large extent) compared to individual approaches. In addition, some dependencies could be hidden dependencies when an analysis of one dependency type (e.g., logical) does not reveal artifacts only linked by another dependency type (semantic). While previous studies have focused on combining dependency information with minimal benefits, this Thesis explores the consistency of these measurements, and whether hidden dependencies arise between artifacts, and in any of the axes studied. In this Thesis, 79 Java projects are empirically studied to investigate (i) the direct influence and the degree of overlap between dependency types on three axes (logical - structural (LSt); logical - semantic (LSe); structural - semantic (StSe)) (structural, logical and semantic), and (ii) the presence of hidden coupling on the axes. The results show that a high proportion of hidden dependencies can be detected on the LSt and StSe axes. Notwithstanding, the LSe axis shows a much smaller proportion of hidden dependencies. Practicable refactoring methods to mitigate hidden dependencies are proposed in the Thesis and discussed with examples.

Nas últimas décadas a tecnologia de realidade virtual tem sido cada vez mais utilizada em várias aplicações na sociedade. Particularmente a partir do início da década de 90, observamos o advento da realidade virtual baseada em multiprojeções, com o surgimento do paradigma de construção de sistemas de realidade virtual totalmente imersivos como por exemplo o CAVE™. Esta tese tem por objetivo apresentar pesquisas e desenvolvimentos relacionados com a implementação do primeiro sistema de multiprojeção totalmente imersivo baseado em aglomerado de computadores convencionais, sistema este denominado de CAVERNA Digital. O trabalho aqui apresentado é composto por um panorama atual do estado da arte das tecnologias de realidade virtual baseadas em multiprojeção. O conceito de aglomerados de computadores convencionais para realidade virtual, ou especificamente VRCluster é apresentado, bem como uma taxonomia de organização interna dos VRClusters. O sistema de multiprojeção da CAVERNA Digital é apresentado, descrevendo em detalhe as opções dos inúmeros subsistemas como projetores, telas, subsistema de vídeo, dispositivos de interação e outros. Outra contribuição desta tese é pela inovação de uma plataforma de visualização interativa voltada para ambientes de realidade virtual imersivos, plataforma esta denominada de JINX, baseada no padrão aberto X3D. Aspectos relacionados com a operação destes sistemas de realidade virtual avançados são apresentados como é o caso das interface de gerenciamento de ambientes imersivos denominado de SIRIUS e do núcleo de gerenciamento de ambientes imersivos denominado de ZEUS. Por fim vários testes de desempenho são realizados para a validação da integração dos inúmeros recursos utilizados na CAVERNA Digital. / In the last decades, virtual reality technology has been increasingly used in many applications for the society. Particularly in the beginning of 90’s, we can observe the advent of virtual reality based in multi-projections, leading to the construction paradigm of CAVE™ like virtual reality systems. The goal of this thesis is to present the research and developments related to the construction of the first multi projection completely immersive system based on commodity computer clusters called CAVERNA Digital. The work here presented is composed by an updated panorama of the state-of-art multi-projection virtual reality technologies. The concept of commodity computer clusters for virtual reality, or specifically VRCluster is shown, as well as the taxonomy for internal organization of the VRClusters. The CAVERNA Digital multi-projection system is shown, including details of the options of uncountable subsystems, like projectors, screens, video, and interaction devices, among others. This thesis contributes with another innovation: the visualization platform, called JINX, based on the open standard X3D. Aspects related to the operation of these advanced virtual reality systems are presented, which is the case of the user interface for immersive environments called SIRIUS and the management core for immersive environments called ZEUS. Finally, various performance tests were conducted to validate the integration of the uncountable resources used in the CAVERNA Digital.

Free/Open Source Software (FOSS) communities often use open bug reporting to allow users to participate by reporting bugs. This practice can lead to more duplicate reports, as inexperienced users can be less rigorous about researching existing bug reports. The purpose of this research is to determine the extent of this problem, and how FOSS projects deal with duplicate bug reports. We examined 12 FOSS projects: 4 small, 4 medium and 4 large, where size was determined by number of code contributors. First, we found that contrary to what has been reported from studies of individual large projects like Mozilla and Eclipse, duplicate bug reports are a problem for FOSS projects, especially medium-sized projects. These medium sized projects struggle with a large number of submissions and duplicates without the resources large projects use for dealing with these. Second, we found that the focus of a project does not affect the number of duplicate bug reports. Our findings point to a need for additional scaffolding and training for bug reporters of all types. Finally, we examine the impact that automatic crash reporting has on these bug repositories. These systems are quickly gaining in popularity and aim to help end-users submit vital bug information to the developers. These tools generate stack traces and memory dumps from software crashes and package these up so end-users can submit them to the project with a single mouse-click. We examined Mozilla's automatic crash reporting systems, Breakpad and Socorro, to determine how these integrate with the open bug reporting process, and whether they add to the confusion of duplicate bug reports. We found that though initial adoption exhibited teething troubles, these systems add significant value and knowledge, though the signal to noise ratio is high and the number of bugs identified per thousand reports is low. / Graduation date: 2012

Open Source Software (OSS) communities are homogenous and their lack of diversity is of concern to many within this field. This problem is becoming more pronounced as it is the practice of many technology companies to use OSS participation as a factor in the hiring process, disadvantaging those who are not a part of this community. We should expect that any field would have a population that reflects the general population given no constraints. The constraints within OSS are documented as being a hostile environment for women and minorities to participate in. Additionally OSS communities rely predominately on volunteers to create and maintain source code, documentation, and user interface as well as the organizational structure of the project. The volunteer nature of OSS projects creates a need for an ongoing pool of participants. This research addresses the lack of diversity along with the continual need for new members by developing a pedagogical paradigm that uses a collaborative environment to promote participation in an OSS project by diverse students. This collaborative environment used a Communities of Practice (CoP) framework to design the course, the indicators of which were used to operationalize the collaboration. The outcomes of this course not only benefit the students by providing them with skills necessary to continue participation and experience for getting a job, but also provide a diverse pool of volunteers for the OSS community. This diverse pool shows promise of creating a more diverse culture within OSS. In the development of this pedagogical paradigm this research looked primarily at student���s perception of the importance of their group members and mentors provided to guide their participation in and contribution to an OSS community. These elements were used to facilitate the formation of a CoP. Self-efficacy was also used as a measure; an increase in self-efficacy is associated with the successful formation of a CoP. Finally the intent to continue, as reported by students, was measured to determine the potential contribution to the OSS community overall. This research was designed to use collaboration to support the formation of a CoP within the groups formed between students based on common interests in the OSS project. Additionally students were provided with a mentor from the community to assist in finding paths to contribute. The Ubuntu project was chosen for its commitment to diversity and its reputation for being a welcoming environment to newcomers, reducing the risk of negative community interactions for students. Written reflections were gathered at mid and end of term and used in conjunction with transcripts or reports of group meetings as well as emails between mentors and mentees. Additionally self-efficacy was measured at the beginning and end of the term. The results of this study show that this pedagogical paradigm supports student contribution. Contribution levels were found to be associated with the level of the formation of a CoP within each group and the use of mentors, as well as attending a live, hands-on bug triage demo and the Global Jam, to gather resources. It was also evident that students intend to continue participating at a rate higher than the average rate for newcomers trying to contribute without the type of support offered by this class. Further research into the examination of the use of reflective dialogue with mentors is recommended. It is also recommended that the results from the operationalization of the indicators of the formation of a CoP be used to assist in a more consistent formation of this important resource across more groups within the class. The results of this research point to the effectiveness of this paradigm to promote contributions to an OSS community. These contributions provide the skills students need to improve their attractiveness to future employers. This class also produced a number of students who intend to continue participating in OSS, providing a diverse pool of potential volunteers to the OSS community. / Graduation date: 2013

This paper seeks to describe the process by which a database-centric web application was redesigned and rewritten to take advantage of Apache’s Lucene - an open-source information retrieval software library written in the Java programming language. After the implementation of a Lucene-based text index of “semi-structured data”, a college radio station's card catalog application was able to deliver higher-quality search results in significantly less time than it was able to do using just a relational database alone. Additionally, the dramatic improvements in speed and performance even allowed the search results interface to be redesigned and enhanced with an improved pagination system and new features such as faceted search/filtering.

It may seem controversial that open-source software (OSS), i.e. software created by voluntary contributions that is available to use, change, and distribute for free, can be utilized for business purposes. Yet, for some firms, commercial OSS software products are the primary source of revenue. In this thesis, these companies are referred to as OSS vendors. Although some OSS vendors have existed for more than thirty years, how they conduct their business has not been extensively studied. Business models as a concept has been widely used in the information and communications technology (ICT) industry, often when describing firms working with OSS. In that context business models often refer to the offering, i.e. the products the firm offers to its customers and how revenues are collected. However, in academia the business model concept has evolved in a broader sense encompassing several fields and into a rich theoretical field itself. This thesis aims to further the understanding on how OSS vendors conduct their business, by using a business model framework, which has been constructed from business model and management theories. This framework was used to study OSS vendors to investigate the configurations of their business models. A cross-case analysis of four carefully selected OSS vendors searched for generic patterns in these configurations. Furthermore, the cases were also studied regarding sustainability and profitability. Two generic business model configurations were found, community immersion and community utilization. OSS vendors found configured according to the community immersion business model are deeply involved with, but also dependent on, the main community project that provides the software for the offering. OSS vendors found configured according to the community utilization business model are not dependent on the OSS project to provide their commercial offerings. Rather, the communities are used in marketing providing brand benefits, a base for recruitment, and in lesser degree functioned as quality assurance. Two of the four studied companies were found to be profitable and sustainable; one operating according to the community immersion business model and the other according to the community utilization business model. The other two companies studied, observed to operate according to the community utilization business model, did not achieve profitability during the time of the study. The findings should further the understanding of how profitable OSS vendors’ business models could be configured, and thus provide practitioners with an understanding on how different business model configurations can affect their strategies and overall business.

Sammanfattning Öppen programvara kan enklast beskrivas som programvara där källkoden är tillgänglig, vilket gör det möjligt att modifiera, utveckla, kopiera och distribuera denna om så önskas (Statskontoret, 2004). Enligt Statskontorets hemsida (2004) används öppen programvara främst för att uppnå ett större oberoende av pris- och licensvillkor inom landets statliga institutioner. Eftersom nyttjandet av öppen programvara medför många fördelar anser Statskontoret (2005) att den offentliga förvaltningen ska beakta möjligheterna med denna typ av mjukvara i större utsträckning. I en rapport från Statskontoret (2004) om erfarenheter av öppen programvara inom den offentliga förvaltningen, anges att majoriteten har valt att anskaffa öppen programvara av besparingsskäl. Vi har i denna uppsats undersökt högskolors och universitets syn på öppen programvara. Detta för att erhålla kunskap om de grundläggande orsakerna bakom olika mjukvaruinvesteringar inom dessa lärosäten. I dagsläget används inte öppen programvara i den utsträckning som är möjlig inom högskolor och universitet i Sverige. Vad beror det på? Vilka faktorer eller kriterier vägs in vid mjukvaruinvesteringsbeslut inom dessa organisationer? Hur har utvecklingen av användandet av öppen programvara sett ut på högskolor och universitet i Sverige, historiskt sett? Syftet är att kartlägga orsakerna bakom investeringar i eller avsaknaden av öppen programvara på högskolor och universitet i Sverige. Då vi haft för avsikt att få en uppfattning om orsaker bakom investeringar i öppen programvara på högskolor och universitet i Sverige, har vi valt att göra kvalitativa intervjuer genom att besöka respektive studieobjekt. Detta då vi varit i behov av information som beskriver sakförhållanden, skeenden och ger uttryck för personliga uppfattningar, för att uppnå vårt syfte och besvara uppsatsens problemställning. När det gäller urvalet av respondenter för undersökningen består populationen av samtliga universitet och högskolor i Sverige, statliga såväl som privata. Vi har valt att begränsa vår undersökning till ett urval av populationen, där samplet består av tre lärosäten som har eller saknar erfarenheter av öppen programvara. De mest centrala iakttagelserna vi gjort i undersökningen är att samtliga universitet/högskolor som deltagit i undersökningen anger att investeringar i öppen programvara inte beror på besparingsskäl, tvärtom är denna typ av programvara ett dyrare alternativ för läroanstalterna. Något annat som observerats är att flera läroanstalter saknar en tydlig supportfunktion för öppen programvara. Statskontorets (2004) anger dock att öppen programvara främst används för att uppnå ett större oberoende av pris- och licensvillkor. Detta oberoende uppfattar läroanstalterna emellertid som mindre tryggt, då allt ansvar förs över på användaren själv, vad gäller uppdateringar, modifieringar etc. Detta överrensstämmer inte med det som anges i rapporten från Statskontorets (2004) vad gäller orsaker bakom investeringar i öppen programvara. Vi anser att universitet och högskolor i Sverige borde vara politiskt oberoende institutioner och ha ett ansvar som gentemot studenter. Detta genom att erbjuda produkter inom utbildningarnas områden som inte valts på grund av en stor aktör, vilkens makt på marknaden kan liknas vid ett monopol. Läroanstalterna har enligt vår åsikt en mycket viktig roll vad gäller den fortsatta utvecklingen och användandet av öppen programvara. Vi anser därför att dessa institutioner borde beakta valmöjligheten, inte endast på grund av ekonomiska skäl utan också för att bidra till en ökad konkurrens på mjukvarumarknaden. / Abstract Open Source Software (OSS) can be defined as software where the source code is accessible by anyone who wants to modify, develop, copy and/or distribute it (Statskontoret, 2004). According to the website of the Swedish government agency for public management (2004) OSS is utilized mainly to become more independent of pricing and licensing conditions within the public institutions in Sweden. As the use of OSS comprises a number of advantages, the agency for public management (2005) believes that the public sector should consider the possibility of using this type of software to a greater extent. In a report from the agency for public management (2004) about the experience of OSS within the public sector, it is stated that the majority have chosen to acquire OSS due to reduction in costs. In this essay we have examined universities view on OSS in order to obtain knowledge regarding the basic reasons behind different software investments within these institutions. Today OSS is not utilized to its full extent within institutions of higher education in Sweden. Why is that? What factors or criteria are taken into consideration when making software investment decisions and how has the use of this type of software evolved over the years within these institutions? The purpose of this essay is to survey the reasons behind investments in, or the lack of OSS within universities in Sweden. As our intention is to get an idea of the reasons behind investments in OSS within these institutions, we have chosen to make qualitative interviews by visiting each object for the study. We have chosen this method as we have been in need of information which describes the course of events and expresses individual opinions, in order to achieve the purpose of the essay and answer the questions stated in the presentation of the problem. Regarding the selection of respondents for the research, the population consists of all universities in Sweden, both public and private. We have chosen to limit the research to a selection of the population, where the sample consists of three universities which have or lack experience from OSS. The most important findings we have made in the research is that all universities that have participated states that investments made in OSS is not due to financial reasons, as they believe that larger investments in this type of software instead would increase the costs. Something else that we have observed is that several universities believe that OSS lacks an apparent support function. However, the agency for public management (2004) states that OSS mainly is used to become more independent of pricing and licensing conditions. This independency is on the other hand looked upon as less secure, by the universities, as the whole responsibility is resting on the shoulders of the user, concerning updates, modifications etc. This does not apply with what is stated in the reports from the Swedish agency for public management (2004) regard-ing the reasons behind investments in OSS. We believe that institutions of higher education should be politically independent and have a responsibility towards the students. This, by offering products within the educational areas that are not chosen due to the power of one multinational company, which bears the resemblance of a monopoly. Universities have according to our opinion a very important roll to play in the future of OSS. Hence we think these institutions should consider the option, not only due to financial reasons but also in order to contribute to an increased competition in the software market.

My dissertation studies the political and corporate reasons behind the adoption of free and open source software technologies in a developing nation, India. This study also attempts to understand the significance of these grassroots technologies for India as it plays on a global arena. How do “free” and “open source software” movements develop in an Indian context and bridge digital divides? The core of the first chapter will establish the questions investigated in this study as well as the significance of this interdisciplinary project for India. It is also important to understand that the varied roles of governments and corporations supporting a new technology, are crucial to its success. Chapter 2 studies the motivations of the Indian government towards adopting free and open-source technologies. The motivations of the industry are different from governmental motivations. In chapter 3, the landscape of Indian software industry players and their reasons for supporting these software technologies are discussed. How do governmental and industry motivations translate? Are they successful and do they live up to their hype? Chapter 4 distinguishes between the hype and reality of the software landscape in India and presents a larger picture of the controversies surrounding software development, in general. A concluding essay of chapter 5 couches the entire project within the process of globalization, speculating its significance for sustainable global information flows.

Open source projects do have requirements; they are, however, mostly informal, text descriptions found in requests, forums, and other correspondence. Understanding such requirements provides insight into the nature of open source projects. Unfortunately, manual analysis of natural language requirements is time-consuming, and for large projects, error-prone. Automated analysis of natural language requirements, even partial, will be of great benefit. Towards that end, I describe the design and validation of an automated natural language requirements classifier for open source software development projects. I compare two strategies for recognizing requirements in open forums of software features. The results suggest that classifying text at the forum post aggregation and sentence aggregation levels may be effective. Initial results suggest that it can reduce the effort required to analyze requirements of open source software development projects. Software development organizations and communities currently employ a large number of software development techniques and methodologies. This implied complexity is also enhanced by a wide range of software project types and development environments. The resulting lack of consistency in the software development domain leads to one important challenge that researchers encounter while exploring this area: specificity. This results in an increased difficulty of maintaining a consistent unit of measure or analysis approach while exploring a wide variety of software development projects and environments. The problem of specificity is more prominently exhibited in an area of software development characterized by a dynamic evolution, a unique development environment, and a relatively young history of research when compared to traditional software development: the open-source domain. While performing research on open source and the associated communities of developers, one can notice the same challenge of specificity being present in requirements engineering research as in the case of closed-source software development. Whether research is aimed at performing longitudinal or cross-sectional analyses, or attempts to link requirements to other aspects of software development projects and their management, specificity calls for a flexible analysis tool capable of adapting to the needs and specifics of the explored context. This dissertation covers the design, implementation, and evaluation of a model, a method, and a software tool comprising a flexible software development analysis framework. These design artifacts use a rule-based natural language processing approach and are built to meet the specifics of a requirements-based analysis of software development projects in the open-source domain. This research follows the principles of design science research as defined by Hevner et. al. and includes stages of problem awareness, suggestion, development, evaluation, and results and conclusion (Hevner et al. 2004; Vaishnavi and Kuechler 2007). The long-term goal of the research stream stemming from this dissertation is to propose a flexible, customizable, requirements-based natural language processing software analysis framework which can be adapted to meet the research needs of multiple different types of domains or different categories of analyses.