Live Streaming with Gossip

Peer-to-peer (P2P) architectures have emerged as a popular paradigm to support the dynamic and scalable nature of distributed systems. This is particularly relevant today, given the tremendous increase in the intensity of information exchanged over the Internet. A P2P system is typically composed of participants that are willing to contribute resources, such as memory or bandwidth, in the execution of a collaborative task providing a benefit to all participants. File sharing is probably the most widely used collaborative task, where each participant wants to receive an individual copy of some file. Users collaborate by sending fragments of the file they have already downloaded to other participants. Sharing files containing multimedia content, files that typically reach the hundreds of megabytes to gigabytes, introduces a number of challenges. Given typical bandwidths of participants of hundreds of kilobits per second to a couple of megabits per second, it is unacceptable to wait until completion of the download before actually being able to use the file as the download represents a non negligible time. From the point of view of the participant, getting the (entire) file as fast as possible is typically not good enough. As one example, Video on Demand (VoD) is a scenario where a participant would like to start previewing the multimedia content (the stream), offered by a source, even though only a fraction of it has been received, and then continue the viewing while the rest of the content is being received. Following the same line of reasoning, new applications have emerged that rely on live streaming: the source does not own a file that it wants to share with others, but shares content as soon as it is produced. In other words, the content to distribute is live, not pre-recorded and stored. Typical examples include the broadcasting of live sports events, conferences or interviews. The gossip paradigm is a type of data dissemination that relies on random communication between participants in a P2P system, sharing similarities with the epidemic dissemination of diseases. An epidemic starts to spread when the source randomly chooses a set of communication partners, of size fanout, and infects them, i.e., it shares a rumor with them. This set of participants, in turn, randomly picks fanout communication partners each and infects them, i.e., share with them the same rumor. This paradigm has many advantages including fast propagation of rumors, a probabilistic guarantee that each rumor reaches all participants, high resilience to churn (i.e., participants that join and leave) and high scalability. Gossip therefore constitutes a candidate of choice for live streaming in large-scale systems. These advantages, however, come at a price. While disseminating data, gossip creates many duplicates of the same rumor and participants usually receive multiple copies of the same rumor. While this is obviously a feature when it comes to guaranteeing good dissemination of the rumor when churn is high, it is a clear disadvantage when spreading large amounts of multimedia data (i.e., ordered and time-critical) to participants with limited resources, namely upload bandwidth in the case of high-bandwidth content dissemination. This thesis therefore investigates if and how the gossip paradigm can be used as a highly effcient communication system for live streaming under the following specific scenarios: (i) where participants can only contribute limited resources, (ii) when these limited resources are heterogeneously distributed among nodes, and (iii) where only a fraction of participants are contributing their fair share of work while others are freeriding. To meet these challenges, this thesis proposes (i) gossip++: a gossip-based protocol especially tailored for live streaming that separates the dissemination of metadata, i.e., the location of the data, and the dissemination of the data itself. By first spreading the location of the content to interested participants, the protocol avoids wasted bandwidth in sending and receiving duplicates of the payload, (ii) HEAP: a fanout adaptation mechanism that enables gossip to adapt participants' contribution with respect to their resources while still preserving its reliability, and (iii) LiFT: a protocol to secure high-bandwidth gossip-based dissemination protocols against freeriders

D.1.3 – Protocols for emergent localities

GDD_HCERES2020This report presents two contributions that illustrate the potential of emerging-locality protocols in large-scale decentralized systems, in two areas of decentralized social computing: recommendation, and eventual consistency of mutable data structures. The first contribution consists of a framework supporting the development of dynamically adaptive decen-tralised recommendation systems. Decentralised recommenders have been proposed to deliver privacy-preserving, personalised and highly scalable on-line recommendations. Current implementations tend, however, to rely on a hard-wired similarity metric that cannot adapt. This constitutes a strong limitation in the face of evolving needs. Our framework address this through a decentralised form of adaptation, in which individual nodes can independently select, and update their own recommendation algorithm, while still collectively contributing to the overall system's mission. Our second contribution addresses the growing demand for differentiated consistency requirements in large-scale applications. A large number of today's applications rely on Eventual Consistency, a consistency model that emphasizes liveness over safety. Designers generally adopt this consistency model uniformly throughout a distributed system due to its ability to scale as the number of users or devices grows larger. But this clashes with the need for differentiated consistency requirements. In this contribution, we address this need by introducing UPS, a novel consistency mechanism that offers differentiated eventual consistency and delivery speed by working in pair with a two-phase epidemic broadcast protocol. We propose a closed-form analysis of our approach's delivery speed, and we evaluate our complete protocol experimentally on a simulated network of one million nodes. To measure the consistency trade-off, we formally define a novel and scalable consistency metric operating at runtime

Have Strength

This story attempts to capture the relationship between terminally ill parents and their young adult children. The story is told by a mother who is trying to prepare her daughter for the inevitable, but her daughter refuses to give up. The mother internally struggles with the maternal need to protect her child from the stress of facing her death and the human need for support and open communication about her failing treatments, her side effects, and her eventual death

Diffusion en directe avec du Gossip

Video streaming has become a killer application for peer-to-peer technologies. By aggregating scarce resources such as upload bandwidth, decentralized video streaming protocols make it possible to serve a video stream to huge numbers of users while requiring very limited investments from broadcasters. In this paper, we present HEAP, a novel peer-to-peer streaming protocol designed for heterogeneous scenarios. Gossip protocols have already shown their effec- tiveness in the context of live video streaming. HEAP, HEterogeneity-Aware gossip Protocol, goes beyond their applicability and performance by incorporating several novel features. First, HEAP includes a fanout-adaptation scheme that tunes the contribution of nodes to the streaming process based on their bandwidth capabilities. Second, HEAP comprises heuristics that improve reliability, as well as operation in the presence of heterogeneous network latency. We extensively evaluate HEAP on a real deployment over 200 nodes on the Grid5000 platform in a variety of settings, and assess its scalability with up to 100k simulated nodes. Our results show that HEAP significantly improves the quality of streamed videos over standard homogeneous gossip protocols, especially when the stream rate is close to the average available bandwidth.Le streaming vidéo est devenu une killer application pour les technologies pair-à- pair. En agrégeant les ressources rares telles que le debit maximale téléversement, les protocoles de diffusion vidéo décentralisée permettent servir un flux vidéo à un grand nombre d’utilisateurs tout en limitant les couts. Dans cet article, nous présentons HEAP, un nouveau protocole de streaming pair-à-pair conçu pour des réseaux hétérogènes. Les protocoles de gossip ont déjà mon- tré leur efficacité dans le contexte du streaming vidéo en direct. HEAP, em HEterogeneity-Aware Gossip Protocol, va au-delà de protocoles existantes en incorporant plusieurs caractéristiques nouvelles. Premièrement, HEAP adapte la contribution des noeuds en fonction de leurs debit maximal. Deuxièmement, HEAP inclut des heuristiques qui améliorent la fiabilité, en présence de latence de réseau hétérogène. Nous évaluons HEAP sur un déploiement réel sur 200 noeuds sur la plate-forme Grid5000 avec une variété de paramètres, et évaluons son passage à l’échelle avec jusqu’à 100k noeuds simulé. Nos résultats montrent que HEAP améliore significativement la qualité des vidéos diffusées par rapport au protocoles standard, surtout lorsque le débit est proche de la bande passante moyenne disponible

RELATiONSHiPs: Partnering Altogether to Raise Achievement

RELATiONSHiPS: Partnering Altogether to Raise Achievement is a presentation that provides participants a systematic approach to building positive relationships with parents, staff, community stakeholders and most importantly students. Growing research continues to convey the importance of developing positive relationships; especially those that have been affected by traumatic events. Participants will learn practical strategies that will equip them to develop positive relationships with all stakeholders. This session will be interactive and will include several hands-on activities all centered on the acronym of R.E.L.A.T.i.O.N.S.H.i.P

Media

Football is the most widely played, watched and studied sport in the world. It’s hard to develop a full understanding of the significance of sport in global society without understanding the significance of football. Studying Football is the first book designed specifically to guide and support the study of football on degree-level courses, across the full range of social-scientific perspectives. Written by a team of leading international football experts, and considering themes of globalization, corporatization and prejudice and discrimination throughout, it introduces key topics in football studies, including: media and celebrity identity, fandom and consumption gender violence racism corruption Every chapter includes up-to-date case study material, a ‘Research in Action’ section and features to aid student understanding and bring theory to life. Studying Football introduces all the key themes and facets of the social-scientific study of football, and is therefore an essential text for students on football studies courses and useful reading for any undergraduates studying the sociology of sport more generally

A Misinformation Blueprint: Mapping warnings in an agile communication system

This thesis provides a high-level view of misinformation that builds an interdisciplinary framework for research to aid in future interventions. It utilizes Buchanan’s wicked-problems approach of design thinking to investigate the drivers of misinformation and where it appears in the chain of communication. There are many forms of inaccuracies throughout the exercise of informing ourselves through communication media. This thesis works to identify misinformation’s placement within information disorder, identify drivers of misinformation and highlight the potential entry points of misinformation into communication media. This research aims to allow us, as a society, a clearer direction for combatting a phenomenon of this size. The final output is a ‘blueprint’ of misinformation shown through a visual ecosystem of information disorder and a system map of communication media. The system map is used to draw attention to two things: (1) Where the drivers of misinformation have the potential to materialize and (2) The channels of communication which are subject to different valves of control. The final ‘blueprint’ is transformed into an interactive display to encourage engagement and awareness

Wikia Fandom Craze: Connecting, Participating, Creating, and Re-negotiating Boundaries

This article draws attention to latest online fandom practices that take place in online participatory environments as a result of intersecting technological and economic variables. After tracing the origins of fan practices in literary theories that regard readers as active agents in reading and meaning-making processes, the present study investigates fandom as a cultural event that is determined by changing technological, economic, and generic conditions. Through the study of Wikia—a vibrant online fan community—the article explores the de-territorialization of fan-fuelled media production and its re-territorialization as one of fans’ ways to enter what Pierre Bourdieu calls the industry’s “circle of belief.” Its wiki structure and technology as well as the latest smart Web tools that it employs allow fans to access, edit, and share media content, as they push the fuzzy boundaries between corporate and grassroots production further. The article maps out the efforts of media platform producers, of the industry, and of the fans to re-negotiate their roles and relationships, and looks into the different types of fan subjectivity that evolve as fans voluntarily succumb to the policies of the popular culture industry