Highly interactive network applications such as online games are rapidly growing in popularity but remain challenging for game providers to support, due to their inherent need for low latency. While cloud computing has proven a useful infrastructure for other applications, existing cloud computing facilities are insufficient for games, due to the unpredictability of their workload, their demands on latency and scale, and the need to support game-specific requirements (e.g., players may wish to play with certain other players already in the game). In this work, we explore whether dynamic optimization of latency and scaling of games can be achieved by supplementing cloud computing infrastructure with seamless wide area virtual machine migration using network based route control. We propose SMOG, a framework that dynamically migrates game servers to their optimal location, and uses orchestrated route control to optimize the network path to the server to minimize observable effects of live server migration. Through deployment of a prototype implementation on a Tier-1 ISP's backbone and a user study, we found SMOG can decrease average end-user latency by up to 60% while performing migration in a manner transparent to game players. While this paper's focus is online games, SMOG is general enough to be used for a variety of latency-sensitive interactive applications such as video conferencing and interactive video streaming.

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SMOG: a cloud platform for seamless wide area migration of online games

Distributed virtual environments (DVEs) have been an active area of research and engineering for more than 20 years. The most widely deployed DVEs are network games such as Quake, Halo, and World of Warcraft (WoW), with millions of users and billions of dollars in annual revenue. Deployed DVEs remain expensive centralized implementations despite significant research outlining ways to distribute DVE workloads. This dissertation shows previous DVE research evaluations are inconsistent with deployed DVE needs. Assumptions about avatar movement and proximity – fundamental scale factors – do not match WoW’s workload, and likely the workload of other deployed DVEs. Alternate workload models are explored and preliminary conclusions presented. Using realistic workloads it is shown that a fully decentralized DVE cannot be deployed to today’s consumers, regardless of its overhead. Residential broadband speeds are improving, and this limitation will eventually disappear. When it does, appropriate security mechanisms will be a fundamental requirement for technology adoption. A trusted auditing system (“Carbon”) is presented which has good security, scalability, and resource characteristics for decentralized DVEs. When performing exhaustive auditing, Carbon adds 27% network overhead to a decentralized DVE with a WoW-like workload. This resource consumption can be reduced significantly, depending upon the DVE’s risk tolerance. Finally, the Pairwise Random Protocol (PRP) is described. PRP enables adversaries to fairly resolve probabilistic activities, an ability missing from most decentralized DVE security proposals. Thus, this dissertation’s contribution is to address two of the obstacles for deploying research on decentralized DVE architectures. First, lack of evidence that research results apply to existing DVEs. Second, the lack of security systems combining appropriate security guarantees with acceptable overhead.

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Distributed virtual environment scalability and security

iCO2 is a networked game that aims to collect human driving behavior data at scale and help researchers better understand how people apply eco-driving practices. iCO2 is an integrated multiplatform game that can be accessed via Web client on Facebook and iPad clients, and supports a shared traffic experience among its users. Here, the authors describe iCO2 and discuss two key efforts and their results. First, they investigated the scalability of Distributed Virtual Environments (DiVE), the networking framework they developed for multiuser 3D virtual world applications. The "area of interest" method that DiVE uses was tested in a laboratory setting and showed promising results on two important metrics: bandwidth and frames per second. Second, they ran a small marketing campaign to collect data from users interacting with the iPad version of iCO2 "in the wild." They then analyzed the users' acceleration behavior, an important aspect of eco-driving.

iCO2: A Networked Game for Collecting Large-Scale Eco-Driving Behavior Data

Model-Driven Game Development Addressing Architectural Diversity and Game Engine-Integration

We present the NIProxy, a flexible network intermediary which aims to improve the Quality of Experience (QoE) of users of networked applications by pushing more intelligence into the network. More specifically, the NIProxy is network- as well as application-aware, meaning it has knowledge of both the transportation network and the application(s) it is serving. This dual awareness is exploited to improve user QoE in two complementary ways. First of all, the NIProxy is capable of dynamically distributing a client's available downstream bandwidth over the different network streams generated by a networked application. Secondly, the NIProxy supports multimedia service provision, meaning it can apply services on multimedia streams on behalf of its clients. An important feature of the NIProxy is that its two QoE-improving mechanisms are not isolated entities but instead can interact with each other. A comprehensive discussion of the NIProxy's software architecture is provided and the implementation of an example service, which adds video transcoding functionality to the NIProxy, is described Finally, presented experimental results clearly demonstrate the effectiveness of our approach.

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The NIProxy: a Flexible Proxy Server Supporting Client Bandwidth Management and Multimedia Service Provision

Several propositions have been made in the last few years on what the optimal type of network architecture should be for networked games. Solutions range from pure peer-to-peer architectures to the classic client/server architecture with server allocation based on a fixed spatial subdivision scheme. In this paper, we elaborate on the design of ALVICNG, an extensible client/server architecture which allows for dynamic allocation of server capacity, combined with extensive means for player activity management and moderation. The framework has been designed in such a way that practical network issues such as NAT traversal are minimized. This is achieved by introducing an extra layer in the architecture, consisting of several proxy servers that channel the messages sent over the network. Besides a theoretical discussion, we will also go into the design of the simulation setup. By using this type of setup, we are able to provide actual figures that demonstrate the viability of the proposed solution.

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Dynamic server allocation in a real-life deployable communications architecture for networked games

The explosive growth of the number of applications based on networked virtual environment technology, both games and virtual communities, shows that these types of applications have become commonplace in a short period of time. However, from a research point of view, the inherent weaknesses in their architectures are quickly exposed. The Architecture for Large-Scale Virtual Interactive Communities (ALVICs) was originally developed to serve as a generic framework to deploy networked virtual environment applications on the Internet. While it has been shown to effectively scale to the numbers originally put forward, our findings have shown that, on a real-life network, such as the Internet, several drawbacks will not be overcome in the near future. It is, therefore, that we have recently started with the development of ALVIC-NG, which, while incorporating the findings from our previous research, makes several improvements on the original version, making it suitable for deployment on the Internet as it exists today.

/pdf/alvic-versus-the-internet-redesigning-a-networked-virtual-bd94elpo5v.pdf

ALVIC versus the internet: redesigning a networked virtual environment architecture

Real-time streaming of multimedia content is increasingly becoming a crucial part of networked applications. A logical consequence of this evolution is a growing demand for services that can be applied on these multimedia streams. In this paper, we present our overlay network which provides such multimedia services. Although these services are application-aware and can thus exploit application-specific knowledge, the overlay network itself is completely generic. Consequently, multiple applications can take advantage of the overlay network, even concurrently. Furthermore, the overlay network is highly extensible, meaning additional services can be added to it easily. Besides describing the architecture of the software component of our overlay network, we also discuss the implementation of two example multimedia services. The first service mixes multiple audio streams into a single stream to enable lightweight voice communication in a Networked Virtual Environment. The second service applies face detection on a video stream to generate meaningful avatars in a meeting system called iConnect. The experimental results produced by these two services clearly demonstrate that our overlay network is capable of providing valuable services for a wide range of networked multimedia applications.

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An overlay network providing application-aware multimedia services

ALVIC-NG is an architecture for networked games based on the classic client/server paradigm. While peer-to-peer and hybrid systems have been extensively researched, the client/server approach provides many advantages that are beneficial or even required from a content, application and service provider's point-of-view. ALVIC-NG consists of an extendable framework which allows for dynamic allocation of server capacity, combined with facilities for player activity management and moderation. This is achieved by introducing an intermediate layer of proxy servers in the architecture to intelligently channel the messages flow. Additionally, ALVIC-NG provides a means for immersive communication by enabling real-time voice chat between participants through an off-the-shelf conferencing system that is closely coupled to the state management facilities and spatial subdivision scheme. Besides a theoretical discussion, we also provide insight into the design of the simulation setup through which we are able to provide actual figures that demonstrate the viability of the proposed solution.

ALVIC-NG: state management and immersive communication for massively multiplayer online games and communities

Correspondence should be addressed to Peter Quax, peter.quax@uhasselt.beReceived 31 January 2008; Revised 25 April 2008; Accepted 16 June 2008Recommended by Jouni SmedThe explosive growth of the number of applications based on networked virtual environment technology, both games and virtualcommunities, shows that these types of applications have become commonplace in a short period of time. However, from aresearch point of view, the inherent weaknesses in their architectures are quickly exposed. The Architecture for Large-ScaleVirtual Interactive Communities (ALVICs) was originally developed to serve as a generic framework to deploy networked virtualenvironment applications on the Internet. While it has been shown to eﬀectively scale to the numbers originally put forward, ourﬁndings have shown that, on a real-life network, such as the Internet, several drawbacks will not be overcome in the near future.It is, therefore, that we have recently started with the development of ALVIC-NG, which, while incorporating the ﬁndings fromour previous research, makes several improvements on the original version, making it suitable for deployment on the Internet asit exists today.Copyright © 2008 Peter Quax et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Bart Cornelissen

Papers

Dynamic server allocation in a real-life deployable communications architecture for networked games

ALVIC versus the internet: redesigning a networked virtual environment architecture

An overlay network providing application-aware multimedia services

ALVIC-NG: state management and immersive communication for massively multiplayer online games and communities

ResearchArticle ALVIC versus the Internet: Redesigning a Networked Virtual Environment Architecture