Alexander Ploss

High-level development of multiserver online games

Multiplayer online games with support for high user numbers must provide mechanisms to support an increasing amount of players by using additional resources. This paper provides a comprehensive analysis of the practically proven multiserver distribution mechanisms, zoning, instancing, and replication, and the tasks for the game developer implied by them. We propose a novel, high-level development approach which integrates the three distribution mechanisms seamlessly in todays online games. As a possible base for this high-level approach, we describe the real-time framework (RTF) 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-server online games and how RTF allows to incorporate the three multiserver distribution mechanisms during the development process. Finally, we describe briefly how RTF provides manageability and maintenance functionality for online games in a grid context with dynamic resource allocation scenarios.

From a single- to multi-server online game: a Quake 3 case study using RTF

Fast-paced action online games like First Person Shooters (FPS) pose high demands on resources and thus require multi-server architectures in order to scale to higher player numbers. However, their multi-server implementation is a challenging task: the game processing needs to be parallelized and the synchronization of the distributed game state needs to be efficiently implemented. As part of the European edutain@grid project 1, we are developing Real-Time Framework (RTF) -- a middleware that provides high-level support for the development of multi-server online games. This paper describes a case study on porting the open-source, single-server Quake 3 Arena game engine to a multi-server architecture using RTF and its state replication approach. We conducted extensive scalability and responsiveness experiments with the ported version of Quake 3 to evaluate the performance of our middleware. The experiments show that the responsiveness of RTF implementation can compete with the original Quake engine, and that the replication support allows to efficiently scale FPS games using multi-server processing.

A dynamic resource management system for real-time online applications on clouds

We consider a challenging class of highly interactive virtual environments, also known as Real-Time Online Interactive Applications (ROIA). Popular examples of ROIA include multi-player online computer games, e-learning and training applications based on real-time simulations, etc. ROIA combine high demands on the scalability and real-time user interactivity with the problem of efficient and economic utilization of resources, which is difficult to achieve due to the changing number of users. We address these challenges by developing the dynamic resource management system RTF-RMS which implements load balancing for ROIA on Clouds. We illustrate how RTF-RMS chooses between three different load-balancing actions and implements Cloud resource allocation. We report experimental results on the load balancing of a multi-player online game in a Cloud environment using RTF-RMS.

A service-oriented interface for highly interactive distributed applications

The emerging class of Real-time Online Interactive Applications (ROIA) include massively-multiplayer online games and e-learning applications. They pose completely new challenges for application developers, including very high level of user interactivity with real-time QoS requirements on distributed performance and scalability. We describe a service-oriented interface that comprises: (1) the Real-Time Framework (RTF) supports a high-level application development process which frees the software developer from the low-level details of distributed computation and communication; (2) the Hoster Management Interface (HMI) supports the transparent resource management for a running application, in particular the creation, controlling and monitoring of ROIA instances. We present our efficient implementation of the interface and describe its use for two particular distributed application scenarios.

Rokkatan: scaling an RTS game design to the massively multiplayer realm

While massively multiplayer online role-playing games involve large numbers of simultaneous players, two other popular game classes - first person action and real-time strategy games - are still rarely discussed for massively multiplayer gaming. This paper presents our work on Rokkatan, an online game which implements the common concept of real-time strategy in a scalable multiplayer design. In order to allow hundreds of users to participate in a single game session, Rokkatan uses our proxy-server network architecture which provides the required scalability and responsiveness required for a fast-paced gaming style. An analytical scalability model integrated into Rokkatan allows to forecast the maximum number of simultaneous players. Our experiments demonstrate good prediction quality of the model and high scalability of Rokkatan, which allows several hundreds of users to participate in a single game session.

Enhancing Grids for Massively Multiplayer Online Computer Games

Massively multiplayer online games (MMOG) are an innovative and challenging class of applications for Grid computing that require large amounts of computational resources for providing a responsive and scalable gameplay for concurrently participating players connected via Internet. We present our Real-Time Framework (RTF)--- a Grid-based middleware for scaling game sessions through a variety of parallelization and distribution techniques. RTF is described within a novel multi-layer service-oriented architecture that comprises three advanced services --- monitoring, capacity planning, and runtime steering --- that use the potential of Grid computing to provide pervasive access to a potentially unbounded number of resources. We report experimental results on the quality of our capacity planning and scalability of the RTF distribution mechanism.

Towards bringing real-time online applications on Clouds

The paper studies an emerging class of Real-Time Online Interactive Applications (ROIA), including multi-player online computer games, e-learning and training applications based on real-time simulations, etc. ROIA combine the challenge of the scalability and real-time user interactivity with the problem of efficient and economic utilization of resources for changing number of users. To address these challenges, we develop a dynamic resource management system which implements load balancing for ROIA on Clouds. We illustrate three different load-balancing actions and report experimental results on bringing a multi-player online game on Cloud.

Towards a Scalable Real-Time Cyberinfrastructure for Online Computer Games

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.

A Case Study on Using RTF for Developing Multi-player Online Games

Real-Time Online Interactive Applications (ROIA) include a broad spectrum of online computer games, as well as challenging distributed e-learning applications, like virtual classrooms and collaborative environments. Development of ROIA poses several complex tasks that currently are addressed at a low level of abstraction. In our previous work, we presented the Real-Time Framework (RTF) - a novel middleware for a high-level development and execution of ROIA in single- and multi-server environments. This paper describes a case study in which a simple but representative online computer game is developed using RTF. We explain how RTF supports the design of data structures and their automatic serialization for network transmission, as well as determining and processing user actions when computing a new game state; the challenge is to provide the state updates to all players in real time at a very high frequency.

A persistent data storage design for real-time interactive applications

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.