On the Development of Real-Time Multi-User Web Applications

With the increasing popularity of the World Wide Web (WWW), end-user applications are moving from desktop to the browser. Web applications have several benefits over native applications: web applications have worldwide availability for any browsing capable device without prior installations. In addition, web applications are easy to distribute and update – once deployed, a web application is instantly available worldwide and further modifications to the system are propagated automatically. The current trend seems to be that web applications are offering collaboration, social connections, and user to user interactions as key features. This can be seen, for example, in the popularity of Facebook, Flickr, and Twitter. Despite all the benefits of the Web, web applications are suffering from the shortcomings in underlying technologies. The Web is strongly rooted in information sharing, and the current technical solutions isolate users rather than make them aware of each other. Since the data cannot be pushed from server to a client, the client must always initiate the communication, which causes a considerable impediment for real-time multi-user web applications, like online chats that have several concurrent users continuously interacting with each other. For such systems, it would be practical if the server could push messages to clients. As a further obstacle, most web application frameworks isolate users in their private sessions that only interact indirectly via the database. This main contribution of this thesis is to make the development of real-time multi-user web applications easier. We elaborate on the difficulties in implementation and design and introduce methods of circumventing them. The main argument is that the Web, the available technology stack, and the frameworks are difficult to use for developing real-time multi-user web applications. However, by selecting the proper approach, the problems can be solved. In this thesis, we have divided the frameworks in groups based on how they make separation of concerns between the client and the server. The separation is important as it determines the thickness of the client and thus where to locate the business logic and the application state. In addition, it has effect on the synchronization of the state between the clients. To collect experiences and for backing up our assumptions, we have implemented real-time multi-user web applications for several frameworks and studied how the frameworks should be used for enabling real-time multi-user application development

An Online Crowd-video service for collaborative event recording

Each day, technological evolution allows access to information in new ways. Traditional text-based newspapers were, in times past the main source of information, but now there is more and more options. First, with radio transmissions, then with the television, and more recently with the Internet. Nowadays, it is easy to get access to information and multimedia through images and video which can be accessed anytime, anywhere. This new source of information is gaining more and more fans, not only because it is easy to reach, but also because it offers the information needed in quick and effective ways. This technological evolution does not stop, so now mankind wants to be more than mere receptors, they also want to take an active part in this process as a source, sharing their own information through those new technologies, with people from all over the world. In this dissertation, we developed a collaborative system where users will share their own videos and collaborate between themselves to develop events related to a particular event. Our intention is to engage users into contributing to grow the available data regarding that event. With this solution we want to offer, not only some features that similar and already existing systems like Youtube and Vimeo present, that we assume to be basic and necessary, but also some new like timelines and the possibility to every user contribute to them.

Forder Application

Dissertação de Mestrado em Engenharia InformáticaIn Portugal eating out is a part of the lifestyle. People meet in coffee shops and restaurants, creating business opportunities for the owners of the places. In the summer season there are many bars that open their terrace service. Like many business, there are some ‘quiet times’ during the day – moments, when the place doesn’t receive so many clients. This project proposes an idea on how to maintain the efficiency of the outdoor service with possibly lower costs for the company. The application presented in the given project enables clients to make their requests directly from the table using a cellphone. In the next step the employee receives a notification with the request and he can prepare and deliver the order. Combining Proximity Communication Technologies and a web and mobile application, the communication between a client and an employee may turn out to be fast and comfortable. This solution can have an impact on the number of employees during a calmer time. It is also expected that the client will be able to receive his order in the faster way, through the implemented innovation

Европейский и национальный контексты в научных исследованиях

В настоящем электронном сборнике «Европейский и национальный контексты в научных исследованиях. Технология» представлены работы молодых ученых по геодезии и картографии, химической технологии и машиностроению, информационным технологиям, строительству и радиотехнике. Предназначены для работников образования, науки и производства. Будут полезны студентам, магистрантам и аспирантам университетов.=In this Electronic collected materials “National and European dimension in research. Technology” works in the fields of geodesy, chemical technology, mechanical engineering, information technology, civil engineering, and radio-engineering are presented. It is intended for trainers, researchers and professionals. It can be useful for university graduate and post-graduate students

Mechanisms Driving Digital New Venture Creation & Performance: An Insider Action Research Study of Pure Digital Entrepreneurship in EdTech

Digitisation has ushered in a new era of value creation where cross border data flows generate more economic value than traditional flows of goods. The powerful new combination of digital and traditional forms of innovation has seen several new industries branded with a ‘tech’ suffix. In the education technology sector (EdTech), which is the industry context of this research, digitisation is driving double-digit growth into a projected $240 billion industry by 2021. Yet, despite its contemporary significance, the field of entrepreneurship has paid little attention to the phenomenon of digital entrepreneurship. As several scholars observe, digitisation challenges core organising axioms of entrepreneurship, with significant implications for the new venture creation process in new sectors such as EdTech. New venture creation no longer appears to follow discrete and linear models of innovation, as spatial and temporal boundaries get compressed. Given the paradigmatic shift, this study investigates three interrelated themes. Firstly, it seeks to determine how a Pure Digital Entrepreneurship (PDE) process develops over time; and more importantly, how the journey challenges extant assumptions of the entrepreneurial process. Secondly, it strives to identify and theorise the deep structures which underlie the PDE process through mechanism-based explanations. Consequently, the study also seeks to determine the causal pathways and enablers which overtly or covertly interrelate to power new venture emergence and performance. Thirdly, it aims to offer practical guidelines for nurturing the growth of PDE ventures, and for the development of supportive ecosystems. To meet the stated objectives, this study utilises an Insider Action Research (IAR) approach to inquiry, which incorporates reflective practice, collaborative inquiry and design research for third-person knowledge production. This three-pronged approach to inquiry allows for the enactment of a PDE journey in real-time, while acquiring a holistic narrative in the ‘swampy lowlands’ of new venture creation. The findings indicate that the PDE process is differentiated by the centrality of digital artifacts in new venture ideas, which in turn result in less-bounded processes that deliver temporal efficiencies – hence, the shorter new venture creation processes than in traditional forms of entrepreneurship. Further, PDE action is defined by two interrelated events – digital product development and digital growth marketing. These events are characterised by the constant forking, merging and termination of diverse activities. Secondly, concurrent enactment and piecemeal co-creation were found to be consequential mechanisms driving temporal efficiencies in digital product development. Meanwhile, data-driven operation and flexibility combine in digital growth marketing, to form higher order mechanisms which considerably reduce the levels of task-specific and outcome uncertainties. Finally, the study finds that digital growth marketing is differentiated from traditional marketing by the critical role of algorithmic agencies in their capacity as gatekeepers. Thus, unlike traditional marketing, which emphasises customer sovereignty, digital growth marketing involves a dual focus on the needs of human and algorithmic stakeholders. Based on the findings, this research develops a pragmatic model of pure digital new venture creation and suggests critical policy guidelines for nurturing the growth of PDE ventures and ecosystems

Mobile phone technology as an aid to contemporary transport questions in walkability, in the context of developing countries

The emerging global middle class, which is expected to double by 2050 desires more walkable, liveable neighbourhoods, and as distances between work and other amenities increases, cities are becoming less monocentric and becoming more polycentric. African cities could be described as walking cities, based on the number of people that walk to their destinations as opposed to other means of mobility but are often not walkable. Walking is by far the most popular form of transportation in Africa’s rapidly urbanising cities, although it is not often by choice rather a necessity. Facilitating this primary mode, while curbing the growth of less sustainable mobility uses requires special attention for the safety and convenience of walking in view of a Global South context. In this regard, to further promote walking as a sustainable mobility option, there is a need to assess the current state of its supporting infrastructure and begin giving it higher priority, focus and emphasis. Mobile phones have emerged as a useful alternative tool to collect this data and audit the state of walkability in cities. They eliminate the inaccuracies and inefficiencies of human memories because smartphone sensors such as GPS provides information with accuracies within 5m, providing superior accuracy and precision compared to other traditional methods. The data is also spatial in nature, allowing for a range of possible applications and use cases. Traditional inventory approaches in walkability often only revealed the perceived walkability and accessibility for only a subset of journeys. Crowdsourcing the perceived walkability and accessibility of points of interest in African cities could address this, albeit aspects such as ease-of-use and road safety should also be considered. A tool that crowdsources individual pedestrian experiences; availability and state of pedestrian infrastructure and amenities, using state-of-the-art smartphone technology, would over time also result in complete surveys of the walking environment provided such a tool is popular and safe. This research will illustrate how mobile phone applications currently in the market can be improved to offer more functionality that factors in multiple sensory modalities for enhanced visual appeal, ease of use, and aesthetics. The overarching aim of this research is, therefore, to develop the framework for and test a pilot-version mobile phone-based data collection tool that incorporates emerging technologies in collecting data on walkability. This research project will assess the effectiveness of the mobile application and test the technical capabilities of the system to experience how it operates within an existing infrastructure. It will continue to investigate the use of mobile phone technology in the collection of user perceptions of walkability, and the limitations of current transportation-based mobile applications, with the aim of developing an application that is an improvement to current offerings in the market. The prototype application will be tested and later piloted in different locations around the globe. Past studies are primarily focused on the development of transport-based mobile phone applications with basic features and limited functionality. Although limited progress has been made in integrating emerging advanced technologies such as Augmented Reality (AR), Machine Learning (ML), Big Data analytics, amongst others into mobile phone applications; what is missing from these past examples is a comprehensive and structured application in the transportation sphere. In turn, the full research will offer a broader understanding of the iii information gathered from these smart devices, and how that large volume of varied data can be better and more quickly interpreted to discover trends, patterns, and aid in decision making and planning. This research project attempts to fill this gap and also bring new insights, thus promote the research field of transportation data collection audits, with particular emphasis on walkability audits. In this regard, this research seeks to provide insights into how such a tool could be applied in assessing and promoting walkability as a sustainable and equitable mobility option. In order to get policy-makers, analysts, and practitioners in urban transport planning and provision in cities to pay closer attention to making better, more walkable places, appealing to them from an efficiency and business perspective is vital. This crowdsourced data is of great interest to industry practitioners, local governments and research communities as Big Data, and to urban communities and civil society as an input in their advocacy activities. The general findings from the results of this research show clear evidence that transport-based mobile phone applications currently available in the market are increasingly getting outdated and are not keeping up with new and emerging technologies and innovations. It is also evident from the results that mobile smartphones have revolutionised the collection of transport-related information hence the need for new initiatives to help take advantage of this emerging opportunity. The implications of these findings are that more attention needs to be paid to this niche going forward. This research project recommends that more studies, particularly on what technologies and functionalities can realistically be incorporated into mobile phone applications in the near future be done as well as on improving the hardware specifications of mobile phone devices to facilitate and support these emerging technologies whilst keeping the cost of mobile devices as low as possible

Web security analysis : an approach to HTML5 risks and pitfalls

Dissertação de mestrado em Engenharia InformáticaWeb applications have become increasingly important in the last years. As more and more applications deal with sensitive and con dential data, the quantity and negative impact of security vulnerabilities has grown as well. To understand this impact, this work presents a study over the most common and risky security vulnerabilities seen on web applications today. Also, with the emerging of the new HTML5 speci cation, an approach is made on how HTML5 will impact web security. The goal is to describe the new features of HTML5 and demonstrate how they may, or may not, introduce new security vulnerabilities to web applications. Understanding the vulnerabilities is only the rst step, as that knowledge is worthless if not applied into the software development life cycle. As so, this works performs a detailed analysis over static analysis tools, methodologies and strategies. Static analysis tools are very powerful, because they can help developers identifying possible vulnerabilities during all the development process. Finally, this work compiles the information gathered in order to provide a set of guidelines on how static analysis tools need to evolve to face the new challenges presented by HTML5 and other emerging technologies. Also, a high level de nition for the structure of a static analysis platform is presented. As a whole, this work intends to be a complete survey over web security vulnerabilities, how they can evolve with the arriving of HTML5 and how can this be approached by static analysis tools.Ao longo dos últimos anos, as aplicações web têm ganho especial importância. Com cada vez mais aplicações a lidar com informação sensível e confidencial, o número e o impacto das vulnerabilidades de segurança tem vindo a aumentar. Para compreender este impacto, este trabalho fornece uma análise sobre as vulnerabilidades de segurança que introduzem mais risco e que são mais comuns nas aplicações web atuais. Com o emergir do HTML5, este trabalho pretende ainda estudar com principal cuidado, o impacto que as novas funcionalidades do HTML5 poderão ter na segurança das aplicações web. O objectivo é apresentar as novas funcionalidades do HTML5 e demonstrar de que forma estas podem, ou não, introduzir novas vulnerabilidades de segurança. Compreender as vulnerabilidades é apenas o primeiro passo, porque esse conhecimento é inútil se não for aplicado durante o processo de desenvolvimento de software. Assim, este trabalho fornece uma análise sobre ferramentas, metodologias e estratégias para análise estática de código. As ferramentas de análise estática de código são extremamente poderosas, pois permitem identificar vulnerabilidades durante todo o processo de desenvolvimento de software. Finalmente, este trabalho compila toda a informação reunida de forma a definir algumas diretrizes sobre como devem evoluir as ferramentas de análise estática de código de forma a conseguirem acompanhar com as alterações introduzidas pelo HTML5 e outras tecnologias emergentes. É ainda definido um modelo de alto nível para a estrutura de uma plataforma de análise estática de código. Concluindo, este trabalho pretende apresentar um estudo detalhado sobre vulnerabilidade de segurança em aplicações web, como estas podem evoluir com a chegada do HTML5 e como devem ser abordadas pelas ferramentas de análise estática de código

Elastic phone : towards detecting and mitigating computation and energy inefficiencies in mobile apps

Mobile devices have become ubiquitous and their ever evolving capabilities are bringing them closer to personal computers. Nonetheless, due to their mobility and small size factor constraints, they still present many hardware and software challenges. Their limited battery life time has led to the design of mobile networks that are inherently different from previous networks (e.g., wifi) and more restrictive task scheduling. Additionally, mobile device ecosystems are more susceptible to the heterogeneity of hardware and from conflicting interests of distributors, internet service providers, manufacturers, developers, etc. The high number of stakeholders ultimately responsible for the performance of a device, results in an inconsistent behavior and makes it very challenging to build a solution that improves resource usage in most cases. The focus of this thesis is on the study and development of techniques to detect and mitigate computation and energy inefficiencies in mobile apps. It follows a bottom-up approach, starting from the challenges behind detecting inefficient execution scheduling by looking only at apps’ implementations. It shows that scheduling APIs are largely misused and have a great impact on devices wake up frequency and on the efficiency of existing energy saving techniques (e.g., batching scheduled executions). Then it addresses many challenges of app testing in the dynamic analysis field. More specifically, how to scale mobile app testing with realistic user input and how to analyze closed source apps’ code at runtime, showing that introducing humans in the app testing loop improves the coverage of app’s code and generated network volume. Finally, using the combined knowledge of static and dynamic analysis, it focuses on the challenges of identifying the resource hungry sections of apps and how to improve their execution via offloading. There is a special focus on performing non-intrusive offloading transparent to existing apps and on in-network computation offloading and distribution. It shows that, even without a custom OS or app modifications, in-network offloading is still possible, greatly improving execution times, energy consumption and reducing both end-user experienced latency and request drop rates. It concludes with a real app measurement study, showing that a good portion of the most popular apps’ code can indeed be offloaded and proposes future directions for the app testing and computation offloading fields.Los dispositivos móviles se han tornado omnipresentes y sus capacidades están en constante evolución acercándolos a los computadoras personales. Sin embargo, debido a su movilidad y tamaño reducido, todavía presentan muchos desafíos de hardware y software. Su duración limitada de batería ha llevado al diseño de redes móviles que son inherentemente diferentes de las redes anteriores y una programación de tareas más restrictiva. Además, los ecosistemas de dispositivos móviles son más susceptibles a la heterogeneidad de hardware y los intereses conflictivos de las entidades responsables por el rendimiento final de un dispositivo. El objetivo de esta tesis es el estudio y desarrollo de técnicas para detectar y mitigar las ineficiencias de computación y energéticas en las aplicaciones móviles. Empieza con los desafíos detrás de la detección de planificación de ejecución ineficientes, mirando sólo la implementación de las aplicaciones. Se muestra que las API de planificación son en gran medida mal utilizadas y tienen un gran impacto en la frecuencia con que los dispositivos despiertan y en la eficiencia de las técnicas de ahorro de energía existentes. A continuación, aborda muchos desafíos de las pruebas de aplicaciones en el campo de análisis dinámica. Más específicamente, cómo escalar las pruebas de aplicaciones móviles con una interacción realista y cómo analizar código de aplicaciones de código cerrado durante la ejecución, mostrando que la introducción de humanos en el bucle de prueba de aplicaciones mejora la cobertura del código y el volumen de comunicación de red generado. Por último, combinando la análisis estática y dinámica, se centra en los desafíos de identificar las secciones de aplicaciones con uso intensivo de recursos y cómo mejorar su ejecución a través de la ejecución remota (i.e.,"offload"). Hay un enfoque especial en el "offload" no intrusivo y transparente a las aplicaciones existentes y en el "offload"y distribución de computación dentro de la red. Demuestra que, incluso sin un sistema operativo personalizado o modificaciones en la aplicación, el "offload" en red sigue siendo posible, mejorando los tiempos de ejecución, el consumo de energía y reduciendo la latencia del usuario final y las tasas de caída de solicitudes de "offload". Concluye con un estudio real de las aplicaciones más populares, mostrando que una buena parte de su código puede de hecho ser ejecutado remotamente y propone direcciones futuras para los campos de "offload" de aplicaciones.Postprint (published version