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

A Web-Based Collaborative Multimedia Presentation Document System

With the distributed and rapidly increasing volume of data and expeditious development of modern web browsers, web browsers have become a possible legitimate vehicle for remote interactive multimedia presentation and collaboration, especially for geographically dispersed teams. To our knowledge, although there are a large number of applications developed for these purposes, there are some drawbacks in prior work including the lack of interactive controls of presentation flows, general-purpose collaboration support on multimedia, and efficient and precise replay of presentations. To fill the research gaps in prior work, in this dissertation, we propose a web-based multimedia collaborative presentation document system, which models a presentation as media resources together with a stream of media events, attached to associated media objects. It represents presentation flows and collaboration actions in events, implements temporal and spatial scheduling on multimedia objects, and supports real-time interactive control of the predefined schedules. As all events are represented by simple messages with an object-prioritized approach, our platform can also support fine-grained precise replay of presentations. Hundreds of kilobytes could be enough to store the events in a collaborative presentation session for accurate replays, compared with hundreds of megabytes in screen recording tools with a pixel-based replay mechanism

Supporting Relationships with Video Chat

Video chat is often called the “closest thing to being there”, but anyone who has used video chat to maintain personal relationships or collaborate with others knows that video chat is not the same as face-to-face interaction. In this thesis, I focus on understanding how video chat can be most effectively designed and used to support relationships, helping to bridge the communication gap for distance separated people. An important difference between video chat and face-to-face interaction is potential effects of seeing oneself. In this thesis, I present two studies exploring this important caveat to supporting relationships remotely. The first study shows that the dominant interface design (which shows one’s own video feed) has measurable effects on people’s experiences and conversations in VMC. The second study focuses on a specific group of people—those with social anxiety—who may be particularly affected by self-view in video chat interfaces. This study shows that interfaces that focus on content (much like the media sharing system presented in this thesis) have the potential to minimize effects of feedback in video chat. Another key difference between video chat and face-to-face interaction is the difficulty of engaging in shared activities. Colocated friends or family members can easily share activities such as walks, movies, or board games; distance separated people have a much harder time doing the same. The work presented in this thesis introduces a synchronous media sharing system that can serve as a powerful tool for maintaining relationships. Building on this work, I show that synchronous media sharing is also useful for creating new relationships as well. Together, the system and studies presented in this thesis provide valuable new insights and techniques for the development of video chat tools that support new and sustained relationships over a distance

Conceitos e métodos para apoio ao desenvolvimento e avaliação de colaboração remota utilizando realidade aumentada

Remote Collaboration using Augmented Reality (AR) shows great potential to establish a common ground in physically distributed scenarios where team-members need to achieve a shared goal. However, most research efforts in this field have been devoted to experiment with the enabling technology and propose methods to support its development. As the field evolves, evaluation and characterization of the collaborative process become an essential, but difficult endeavor, to better understand the contributions of AR. In this thesis, we conducted a critical analysis to identify the main limitations and opportunities of the field, while situating its maturity and proposing a roadmap of important research actions. Next, a human-centered design methodology was adopted, involving industrial partners to probe how AR could support their needs during remote maintenance. These outcomes were combined with literature methods into an AR-prototype and its evaluation was performed through a user study. From this, it became clear the necessity to perform a deep reflection in order to better understand the dimensions that influence and must/should be considered in Collaborative AR. Hence, a conceptual model and a humancentered taxonomy were proposed to foster systematization of perspectives. Based on the model proposed, an evaluation framework for contextualized data gathering and analysis was developed, allowing support the design and performance of distributed evaluations in a more informed and complete manner. To instantiate this vision, the CAPTURE toolkit was created, providing an additional perspective based on selected dimensions of collaboration and pre-defined measurements to obtain “in situ” data about them, which can be analyzed using an integrated visualization dashboard. The toolkit successfully supported evaluations of several team-members during tasks of remote maintenance mediated by AR. Thus, showing its versatility and potential in eliciting a comprehensive characterization of the added value of AR in real-life situations, establishing itself as a generalpurpose solution, potentially applicable to a wider range of collaborative scenarios.Colaboração Remota utilizando Realidade Aumentada (RA) apresenta um enorme potencial para estabelecer um entendimento comum em cenários onde membros de uma equipa fisicamente distribuídos precisam de atingir um objetivo comum. No entanto, a maioria dos esforços de investigação tem-se focado nos aspetos tecnológicos, em fazer experiências e propor métodos para apoiar seu desenvolvimento. À medida que a área evolui, a avaliação e caracterização do processo colaborativo tornam-se um esforço essencial, mas difícil, para compreender as contribuições da RA. Nesta dissertação, realizámos uma análise crítica para identificar as principais limitações e oportunidades da área, ao mesmo tempo em que situámos a sua maturidade e propomos um mapa com direções de investigação importantes. De seguida, foi adotada uma metodologia de Design Centrado no Humano, envolvendo parceiros industriais de forma a compreender como a RA poderia responder às suas necessidades em manutenção remota. Estes resultados foram combinados com métodos da literatura num protótipo de RA e a sua avaliação foi realizada com um caso de estudo. Ficou então clara a necessidade de realizar uma reflexão profunda para melhor compreender as dimensões que influenciam e devem ser consideradas na RA Colaborativa. Foram então propostos um modelo conceptual e uma taxonomia centrada no ser humano para promover a sistematização de perspetivas. Com base no modelo proposto, foi desenvolvido um framework de avaliação para recolha e análise de dados contextualizados, permitindo apoiar o desenho e a realização de avaliações distribuídas de forma mais informada e completa. Para instanciar esta visão, o CAPTURE toolkit foi criado, fornecendo uma perspetiva adicional com base em dimensões de colaboração e medidas predefinidas para obter dados in situ, que podem ser analisados utilizando o painel de visualização integrado. O toolkit permitiu avaliar com sucesso vários colaboradores durante a realização de tarefas de manutenção remota apoiada por RA, permitindo mostrar a sua versatilidade e potencial em obter uma caracterização abrangente do valor acrescentado da RA em situações da vida real. Sendo assim, estabelece-se como uma solução genérica, potencialmente aplicável a uma gama diversificada de cenários colaborativos.Programa Doutoral em Engenharia Informátic

Supporting Participation Through Live Media

Throughout the past century, live media has grown to play a significant role in how we experience the world. Live media connects people in real-time with events happening around the world and helps people establish shared social realities. Recent live forms enabled by the internet are shifting the paradigm away from just passively watching to actively participating. This has significant implications for how we engage in critical aspects of society, including education, politics, work, play, and everyday life. In this work, we focus on understanding emerging live media phenomena and designing new forms to support participation. We do this through two core approaches: qualitative investigations and live media probes. To build an understanding of practice and communities, we conduct qualitative investigations of two situated live media contexts: the video game live streaming site Twitch and massive open online courses (MOOCs). Using Marshall McLuhan’s concept of hot and cool media, we explore how live streaming as a medium affords building these online communities through participation in shared experiences. Building on these findings, we design, deploy, and evaluate live media probes. These probes implement new forms of live media, with the goal of eliciting new forms of live experience and participation. We first design Rivulet, a live media probe supporting new participatory modalities and multiple simultaneous live streams. Through our investigation of Rivulet, we discover how, by incorporating new modalities, we can support higher-impact forms of participation in live experiences. Next, we design Collaborative Live Media Curation (CLMC), a new live media form enabling the collaborative real-time assemblage of web media including text, images, sketch, and live video and audio. We deploy LiveMâché, a CLMC probe, in four situated online learning contexts to support participatory learning activities. We find that CLMC supports new forms of real-time conversational grounding and participation. In conclusion, we summarize and discuss our findings and discuss future directions for live media research

MediaSync: Handbook on Multimedia Synchronization

This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users' perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences