Real-time Online Interactive Applications (ROIA) like multiplayer online games usually work in a persistent environment (also called virtual world) which continues to exist and evolve also while the user is offline and away from the application. This paper deals with storing persistent data of real-time interactive applications in modern relational databases. We describe a preliminary design of the Entity Persistence Module (EPM) middleware which liberates the application developer from writing and maintaining complex and error-prone, application-specific code for persistent data management.

This paper describes how the performance potential of multi-core processors can be used to accelerate multi-user online games and other interactive applications. We developed DependenTS (Dependent Task Scheduler) - a task scheduling C++ library for multi-core systems. DependenTS is used within our Real-Time Framework (RTF) in order to overlap the application computations with communication-related actions. By executing the overlapped actions on multiple cores, we improve the application performance, in particular we increase the maximal number of players which can access a game simultaneously.

We consider a challenging class of emerging, highly interactive virtual environments which we call Real-Time Online Interactive Applications (ROIA). Popular examples include multi-player online computer games, e-learning and training applications based on real-time simulations, etc. ROIA combine tough demands on the level of scalability and highly intensive user interactivity with real-time QoS requirements on distributed performance. A major problem in this context is the efficient and economic utilization of server resources for distributed service provision, which is very difficult to achieve due to the variable numbers of users. In this paper, we propose a novel combination of two platforms that address this challenge by utilizing Cloud Computing for ROIA provision: we extend the Real-Time Framework (RTF) by the novel Cloud resource management system RTF-RMS. RTF is a high-level development platform that provides suitable management and scalability mechanisms for ROIA. RTF-RMS is a resource management system on top of RTF that implements workload analysis and distribution techniques. We illustrate how RTF-RMS interacts with RTF and describe how both platforms are used together to scale application servers up and down during runtime to conform to a changing number of users.

Large-scale Massively Multiplayer Online Games (MMOGs) and other networked applications pose challenging performance requirements such as low response times (down to 100 ms for action games like First-Person Shooters) and high update rates (up to 50 Hz). They require multi-server architectures in order to scale to higher player numbers (up to 105 in a single application session). During the application development process, it is necessary to study performance properties such as response time to user actions or CPU consumption in order to optimize the application. To analyse performance properties, the application developer needs to (i) model these properties, (ii) collect information about the variables of interest, and (iii) process the collected information to study the results. In this paper, we propose a novel tool set (Netlag) that supports the collection and processing of variables of interest in the context of MMOGs. The tool set consists of a C++ library that allows to collect and store information in a generic way, as well as a Java application that visualises the collected information. As a case study, we conduct how Netlag is used to evaluate the performance and scalability of an example MMOG application. Furthermore, we describe measurements of the overhead introduced by Netlag which demonstrate that its application intrusion is minimal, thus proving its good applicability for MMOGs and other networked applications.

We propose a novel cyberinfrastructure for an emerging class of Internet-based real-time online interactive applications (ROIA). The most challenging representative of this application class are massively multi-player online games. We present the results of the European project Edutain@Grid on the development of efficient cyberinfrastructure and scalable applications. We report experimental results demonstrating the performance and scalability of our approach.

Real-Time Online Interactive Applications (ROIA) are an increasingly important class of applications including multiplayer online computer games and simulation-based e-learning. They are usually expected to support high user numbers and thus require mechanisms to accommodate increasing load by using additional resources. This paper presents first results of the research and development project edutain@grid, including a comprehensive analysis of the application class and the new challenges regarding software development. We propose a novel, high-level development approach for ROIA which integrates three distribution mechanisms in today's online games – zoning, instancing and replication. As a first implementation of the approach, we describe the RTF (Real-Time Framework) middleware system which liberates the developer from low-level tasks and allows him to stay at high level of design abstraction. We explain how RTF supports the implementation of single and multi-server online games and how RTF incorporates various distribution mechanisms during the development process.