Online gaming franchises such as World of Tanks, Defense of the Ancients, and StarCraft have attracted hundreds of millions of users who, apart from playing the game, also socialize with each other through gaming and viewing gamecasts. As a form of User Generated Content (UGC), gamecasts play an important role in user entertainment and gamer education. They deserve the attention of both industrial partners and the academic communities, corresponding to the large amount of revenue involved and the interesting research problems associated with UGC sites and social networks. Although previous work has put much effort into analyzing general UGC sites such as YouTube, relatively little is known about the gamecast sharing sites. In this work, we provide the first comprehensive study of gamecast sharing sites, including commercial streaming-based sites such as Amazon's Twitch.tv and community-maintained replay-based sites such as WoTreplays. We collect and share a novel dataset on WoTreplays that includes more than 380,000 game replays, shared by more than 60,000 creators with more than 1.9 million gamers. Together with an earlier published dataset on Twitch.tv, we investigate basic characteristics of gamecast sharing sites, and we analyze the activities of their creators and spectators. Among our results, we find that (i) WoTreplays and Twitch.tv are both fast-consumed repositories, with millions of gamecasts being uploaded, viewed, and soon forgotten; (ii) both the gamecasts and the creators exhibit highly skewed popularity, with a significant heavy tail phenomenon; and (iii) the upload and download preferences of creators and spectators are different: while the creators emphasize their individual skills, the spectators appreciate team-wise tactics. Our findings provide important knowledge for infrastructure and service improvement, for example, in the design of proper resource allocation mechanisms that consider future gamecasting and in the tuning of incentive policies that further help player retention.@en

Multiplayer Online Games (MOGs) like Defense of the Ancients and StarCraft II have attracted hundreds of millions of users who communicate, interact, and socialize with each other through gaming. In MOGs, rich social relationships emerge and can be used to improve gaming services such as match recommendation and game population retention, which are important for the user experience and the commercial value of the companies who run these MOGs. In this work, we focus on understanding social relationships in MOGs. We propose a graph model that is able to capture social relationships of a variety of types and strengths. We apply our model to real-world data collected from three MOGs that contain in total over ten years of behavioral history for millions of players and matches. We compare social relationships in MOGs across different game genres and with regular online social networks like Facebook. Taking match recommendation as an example application of our model, we propose SAMRA, a Socially Aware Match Recommendation Algorithm that takes social relationships into account. We show that our model not only improves the precision of traditional link prediction approaches, but also potentially helps players enjoy games to a higher extent.@en

Data enters are at the core of a wide variety of daily ICT utilities, ranging from scientific computing to online gaming. Due to the scale of today's data enters, the failure of computing resources is a common occurrence that may disrupt the availability of ICT services, leading to revenue loss. Although many high availability (HA) techniques have been proposed to mask resource failures, datacenter users' -- who rent datacenter resources and use them to provide ICT utilities to a global population' -- still have limited management options for dynamically selecting and configuring HA techniques. In this work, we propose Availability-on-Demand (AoD), a mechanism consisting of an API that allows datacenter users to specify availability requirements which can dynamically change, and an availability-aware scheduler that dynamically manages computing resources based on user-specified requirements. The mechanism operates at the level of individual service instance, thus enabling fine-grained control of availability, for example during sudden requirement changes and periodic operations. Through realistic, trace-based simulations, we show that the AoD mechanism can achieve high availability with low cost. The AoD approach consumes about the same CPU hours but with higher availability than approaches which use HA techniques randomly. Moreover, comparing to an ideal approach which has perfect predictions about failures, it consumes 13% to 31% more CPU hours but achieves similar availability for critical parts of applications.@en

Social interactions in multiplayer online games are an essential feature for a growing number of players world-wide. However, this interaction between the players might lead to the emergence of undesired and unintended behavior, particularly if the game is designed to be highly competitive. Communication channels might be abused to harass and verbally assault other players, which negates the very purpose of entertainment games by creating a toxic player-community. By using a novel natural language processing framework, we detect profanity in chat-logs of a popular Multiplayer Online Battle Arena (MOBA) game and develop a method to classify toxic remarks. We show how toxicity is non-trivially linked to game success.@en

Although Multi-Avatar Distributed Virtual Environments (MAVEs) such as Real-Time Strategy (RTS) games entertain daily hundreds of millions of online players, their current designs do not scale. For example, even popular RTS games such as the StarCraft series support in a single game instance only up to 16 players and only a few hundreds of avatars loosely controlled by these players, which is a consequence of the Event-Based Lockstep Simulation (EBLS) scalability mechanism they employ. Through empirical analysis, we show that a single Area of Interest (AoI), which is a scalability mechanism that is sufficient for single-avatar virtual environments (such as Role-Playing Games), also cannot meet the scalability demands of MAVEs. To enable scalable MAVEs, in this work we propose Area of Simulation (AoS), a new scalability mechanism, which combines and extends the mechanisms of AoI and EBLS. Unlike traditional AoI approaches, which employ only update-based operational models, our AoS mechanism uses both event-based and update-based operational models to manage not single, but multiple areas of interest. Unlike EBLS, which is traditionally used to synchronize the entire virtual world, our AoS mechanism synchronizes only selected areas of the virtual world. We further design an AoS-based architecture, which is able to use both our AoS and traditional AoI mechanisms simultaneously, dynamically trading-off consistency guarantees for scalability. We implement and deploy this architecture and we demonstrate that it can operate with an order of magnitude more avatars and a larger virtual world without exceeding the resource capacity of players' computers.@en