Re-engineering jake2 to work on a grid using the GridGain Middleware

With the advent of Massively Multiplayer Online Games (MMOGs), engineers and designers of games came across with many questions that needed to be answered such as, for example, "how to allow a large amount of clients to play simultaneously on the same server?", "how to guarantee a good quality of service (QoS) to a great number of clients?", "how many resources will be necessary?", "how to optimize these resources to the maximum?". A possible answer to these questions relies on the usage of grid computing. Taking into account the parallel and distributed nature of grid computing, we can say that grid computing allows for more scalability in terms of a growing number of players, guarantees shorter communication time between clients and servers, and allows for a better resource management and usage (e.g., memory, CPU, core balancing usage, etc.) than the traditional serial computing model. However, the main focus of this thesis is not about grid computing. Instead, this thesis describes the re-engineering process of an existing multiplayer computer game, called Jake2, by transforming it into a MMOG, which is then put to run on a grid

The Playing Session: Enhanced Playability for Mobile Gamers in Massive Metaverses

Internet ubiquity and the success of mobile gaming devices are increasing the interest in wireless access to virtual environments. Mainly due to the mobility factor and wireless medium features, traditional gaming architectures are not enough to guarantee good levels of playability and fairness to mobile gamers. We suggest a new mechanism, called playing session, capable of controlling communications between mobile devices and the game infrastructure. In case of network failures, a mimicking mechanism is in charge of playing, until the communication channel is restored. The goal is to reproduce, with an adequate level of mimesis, the user behavior. According to this approach, it will be possible to enhance the overall playability of Internet games without requiring any modification to the existing communication infrastructure

An Information-Theoretic Framework for Consistency Maintenance in Distributed Interactive Applications

Distributed Interactive Applications (DIAs) enable geographically dispersed users to interact with each other in a virtual environment. A key factor to the success of a DIA is the maintenance of a consistent view of the shared virtual world for all the participants. However, maintaining consistent states in DIAs is difficult under real networks. State changes communicated by messages over such networks suffer latency leading to inconsistency across the application. Predictive Contract Mechanisms (PCMs) combat this problem through reducing the number of messages transmitted in return for perceptually tolerable inconsistency. This thesis examines the operation of PCMs using concepts and methods derived from information theory. This information theory perspective results in a novel information model of PCMs that quantifies and analyzes the efficiency of such methods in communicating the reduced state information, and a new adaptive multiple-model-based framework for improving consistency in DIAs. The first part of this thesis introduces information measurements of user behavior in DIAs and formalizes the information model for PCM operation. In presenting the information model, the statistical dependence in the entity state, which makes using extrapolation models to predict future user behavior possible, is evaluated. The efficiency of a PCM to exploit such predictability to reduce the amount of network resources required to maintain consistency is also investigated. It is demonstrated that from the information theory perspective, PCMs can be interpreted as a form of information reduction and compression. The second part of this thesis proposes an Information-Based Dynamic Extrapolation Model for dynamically selecting between extrapolation algorithms based on information evaluation and inferred network conditions. This model adapts PCM configurations to both user behavior and network conditions, and makes the most information-efficient use of the available network resources. In doing so, it improves PCM performance and consistency in DIAs

Interaktive latenzkritische Anwendungen in mobilen Ad-hoc Netzen

In this thesis we discuss the challenges that latency-sensitive interactive applications face in mobile ad-hoc networks. By using multi-player games as an example, we argue that the traditional client-server architecture is unsuitable for this new environment. We consequently create a novel communication architecture as well as quality of service mechanisms that can support the network requirements of such applications in mobile environments. By using a number of distributed zone servers that are selected and managed dynamically by our server selection algorithm, we provide a scalable approach that offers the necessary redundancy. Furthermore, we propose additional quality of service mechanisms to reduce latency and packet loss for interactive applications. We evaluate our approach through network simulation and realistic mobile gaming scenarios. The performance of our evaluation is checked against real-world measurements.In dieser Arbeit werden die Probleme und Herausforderungen von latenz-kritischen interactiven Computeranwendungen in mobilen Ad-hoc Netzen untersucht. Am Beispiel von Mehrbenutzercomputerspielen zeigen wir, dass traditionelle Client-Server Architekturen für diese neuen Umgebungen ungeeignet sind. Im Rahmen dieser Arbeit wird daher eine neue Kommunikationsarchitektur sowie verschiedene Mechanismen zur Erhöhung der Dienstgüte vorgeschlagen. Mit Hilfe von Zonenserver, die durch den Serverauswahlalgorithmus ausgesucht und verwaltet werden zeigen wir einen Ansatz auf, der sowohl bezüglich der Netzgröße skalierbar ist als auch die notwendige Redundanz bereitstellt. Wir zeigen die Funktionalität und die Leistung unseres Ansatzes mit Hilfe von Netzsimulationen bei denen realistische Szenarien für mobiles Spielen simuliert werden. Der hierbei benutze Netzsimulator wurde dafür auf Basis von eigenen Messungen verbessert und für das jeweilige Szenario passend eingestellt

Reducing Internet Latency : A Survey of Techniques and their Merit

Bob Briscoe, Anna Brunstrom, Andreas Petlund, David Hayes, David Ros, Ing-Jyh Tsang, Stein Gjessing, Gorry Fairhurst, Carsten Griwodz, Michael WelzlPeer reviewedPreprin

Runtime reconfiguration of physical and virtual pervasive systems

Today, almost everyone comes in contact with smart environments during their everyday’s life. Environments such as smart homes, smart offices, or pervasive classrooms contain a plethora of heterogeneous connected devices and provide diverse services to users. The main goal of such smart environments is to support users during their daily chores and simplify the interaction with the technology. Pervasive Middlewares can be used for a seamless communication between all available devices and by integrating them directly into the environment. Only a few years ago, a user entering a meeting room had to set up, for example, the projector and connect a computer manually or teachers had to distribute files via mail. With the rise of smart environments these tasks can be automated by the system, e.g., upon entering a room, the smartphone automatically connects to a display and the presentation starts. Besides all the advantages of smart environments, they also bring up two major problems. First, while the built-in automatic adaptation of many smart environments is often able to adjust the system in a helpful way, there are situations where the user has something different in mind. In such cases, it can be challenging for unexperienced users to configure the system to their needs. Second, while users are getting increasingly mobile, they still want to use the systems they are accustomed to. As an example, an employee on a business trip wants to join a meeting taking place in a smart meeting room. Thus, smart environments need to be accessible remotely and should provide all users with the same functionalities and user experience. For these reasons, this thesis presents the PerFlow system consisting of three parts. First, the PerFlow Middleware which allows the reconfiguration of a pervasive system during runtime. Second, with the PerFlow Tool unexperi- enced end users are able to create new configurations without having previous knowledge in programming distributed systems. Therefore, a specialized visual scripting language is designed, which allows the creation of rules for the commu- nication between different devices. Third, to offer remote participants the same user experience, the PerFlow Virtual Extension allows the implementation of pervasive applications for virtual environments. After introducing the design for the PerFlow system, the implementation details and an evaluation of the developed prototype is outlined. The evaluation discusses the usability of the system in a real world scenario and the performance implications of the middle- ware evaluated in our own pervasive learning environment, the PerLE testbed. Further, a two stage user study is introduced to analyze the ease of use and the usefulness of the visual scripting tool

Treatment-Based Classi?cation in Residential Wireless Access Points

IEEE 802.11 wireless access points (APs) act as the central communication hub inside homes, connecting all networked devices to the Internet. Home users run a variety of network applications with diverse Quality-of-Service requirements (QoS) through their APs. However, wireless APs are often the bottleneck in residential networks as broadband connection speeds keep increasing. Because of the lack of QoS support and complicated configuration procedures in most off-the-shelf APs, users can experience QoS degradation with their wireless networks, especially when multiple applications are running concurrently. This dissertation presents CATNAP, Classification And Treatment iN an AP , to provide better QoS support for various applications over residential wireless networks, especially timely delivery for real-time applications and high throughput for download-based applications. CATNAP consists of three major components: supporting functions, classifiers, and treatment modules. The supporting functions collect necessary flow level statistics and feed it into the CATNAP classifiers. Then, the CATNAP classifiers categorize flows along three-dimensions: response-based/non-response-based, interactive/non-interactive, and greedy/non-greedy. Each CATNAP traffic category can be directly mapped to one of the following treatments: push/delay, limited advertised window size/drop, and reserve bandwidth. Based on the classification results, the CATNAP treatment module automatically applies the treatment policy to provide better QoS support. CATNAP is implemented with the NS network simulator, and evaluated against DropTail and Strict Priority Queue (SPQ) under various network and traffic conditions. In most simulation cases, CATNAP provides better QoS supports than DropTail: it lowers queuing delay for multimedia applications such as VoIP, games and video, fairly treats FTP flows with various round trip times, and is even functional when misbehaving UDP traffic is present. Unlike current QoS methods, CATNAP is a plug-and-play solution, automatically classifying and treating flows without any user configuration, or any modification to end hosts or applications

Contribución al soporte de aplicaciones multimedia multiusuario de alta interactividad en el subsistema IP multimedia

Las aplicaciones multimedia multiusuario de alto grado de interactividad (HIMMA) están en auge actualmente gracias a la evolución de las redes de acceso fijas y móviles, las mejoras en los terminales de usuario y a la propia oferta de aplicaciones existente. Aplicaciones como las de trabajo colaborativo, juegos multijugador, tele-enseñanza o telemedicina fomentan la comunicación entre usuarios en distintos ámbitos profesionales y de entretenimiento, tanto en entornos fijos como en movilidad. Estas aplicaciones requieren generalmente un conjunto de funciones comunes como son la gestión de usuarios (alta, baja, almacenamiento de perfil, creación de grupos), información sobre servicios (presencia, predisposición a participar en actividades, etc.) y gestión de las comunicaciones (establecimiento de sesiones multiusuario, notificación de eventos, soporte de múltiples dispositivos, gestión del estado, calidad de servicio en la red, etc.). Todas estas funciones deben proporcionarse por infraestructura específica de la aplicación en caso de desplegarse en una red que sólo proporcione conectividad IP (como la propia Internet). Esta situación conduce a desarrollos habitualmente propietarios o específicos que dan lugar a deseconomías de escala y dificultan la interoperabilidad entre aplicaciones y, por tanto, entre usuarios, problema que constituye la motivación principal de la Tesis. El Subsistema IP Multimedia (IMS) está definido por el 3GPP como arquitectura estándar para la provisión de servicios Todo-IP en redes móviles y ha sido adoptado por otros foros de estandarización para entornos de telefonía fija, redes de cable, fibra e inalámbricas. La arquitectura de IMS está basada en el establecimiento de sesiones mediante el protocolo SIP del IETF y cuenta con un conjunto de servicios básicos, denominados habilitadores, entre los que se incluyen gestión de grupos, presencia, mensajería, etc. En esta Tesis se aborda la adecuación de IMS como plataforma para la provisión de aplicaciones multimedia multiusuario de alto grado de interactividad, estudiando las aplicaciones multiusuario provistas de forma por estándar por IMS (videoconferencia, Pulsar para Hablar) y proponiendo como contribución básica un marco genérico de soporte a aplicaciones HIMMA basado en los estándares de IMS que facilita el desarrollo de este tipo de aplicaciones. Este marco de soporte se aprovecha de las posibilidades de extensión de IMS, a través del concepto de habilitador, y comprende dos elementos fundamentales: un habilitador ligero para la gestión de aplicaciones HIMMA y un middleware para clientes que ofrece una interfaz Java de alto nivel que facilita el desarrollo de aplicaciones HIMMA sin infraestructura específica aprovechando las capacidades de la red IMS. Finalmente, se presenta la aplicabilidad de las contribuciones anteriores a dos tipos de escenarios relevantes para las aplicaciones HIMMA: juegos multijugador en red y servicios profesionales. Abstract Highly interactive multimedia multiparty applications (HIMMA) are gaining interest in the TIC market thanks to the evolution of fixed and radio access networks, improvements in user terminals and the broad range of existing applications. Applications such as collaborative work, multiplayer networked games, e-learning and e-health encourage communication among users in a variety of professional and entertainment spheres, both in fixed and mobile environments. These applications usually require a set of common functions such as user management (creation of records, storage of the user profile, creation of groups, etc.), information services (presence, willingness to participate in activities, etc.) and communications management (establishment of multiparty sessions, event notification, support for multiple devices, state management, quality of service in the network, etc.). Should the network provide only IP connectivity (like the Internet), all the previous functions must be provided by application-specific infrastructure deployed in the network. This situation usually leads to custom developments of the required functions, where different providers duplicate the same functionality. It also generates scale diseconomies and makes interoperability among applications difficult and, thus, among users. The IP Multimedia Subsystem (IMS) is defined by 3GPP as a standard architecture for the provision of All-IP services in mobile networks and has been adopted by other standardization bodies for fixed telephony, cable, fiber optic and wireless networks. The IMS architecture is based on the SIP signaling protocol to create and maintain communication sessions. It also includes a set of basic services, namely service enablers, including group management, rich presence, messaging and so on. This PhD thesis addresses the suitability of the IMS as a platform for the provision of highly interactive multimedia multiparty applications and proposes as global contribution a generic standards-based framework to ease the development and deployment of HIMMA applications. This framework makes the most of the extensibility of IMS architecture and protocols through the concept of service enabler, comprising two core elements: a Lightweight Conferencing Enabler (LCE) to manage HIMMA applications, and a HIMMA middleware which provides developers a high-level Java interface to ease the development of HIMMA applications without application-specific infrastructure. Finally, we present the applicability of the previous contributions to two types of relevant scenarios: multiplayer networked games and professional services