Hamish Taylor

Mediator: a design framework for P2P MMOGs

With widespread use of the Internet, Massively Multiplayer Online Games (MMOGs) are becoming increasingly popular. As MMOGs scale up, conventional Client/Server (C/S) architectures exhibit various drawbacks in scalability, reliability, and redundancy. This paper presents a new Peer-to-Peer (P2P) MMOG design framework, Mediator, using a super-peer network with multiple super-peer (Mediator) roles. Mediator is novel in integrating four elements: a reward scheme, distributed resource discovery, load-management and super-peer selection. The reward scheme differentiates a peers contribution from their reputation, and pursues symmetrical reciprocity as well as discouraging misdemeanours. A deadline-driven auction protocol is proposed for distributed resource discovery. Furthermore, both common-peer and super-peer workloads are approximately balanced using a two-level load-management scheme, and super-peers are selected in a flexible policy-based way. In this framework, the functionalities of a traditional game server are distributed, capitalising on the potential of P2P networks, and enabling the MMOG to scale better in both communication and computation. A proof-of-concept prototype of this framework is described, and ongoing work is discussed.

Design issues for Peer-to-Peer Massively Multiplayer Online Games

Massively Multiplayer Online Games (MMOGs) are increasing in both popularity and scale, and while classical Client/Server (C/S) architectures convey some benefits, they suffer from significant technical and commercial drawbacks. This realisation has sparked intensive research interest in adapting MMOGs to Peer-to-Peer (P2P) architectures. This paper articulates a comprehensive set of six design issues to be addressed by P2P MMOGs, namely Interest Management (IM), game event dissemination, Non-Player Character (NPC) host allocation, game state persistency, cheating mitigation and incentive mechanisms. Design alternatives for each issue are systematically compared, and their interrelationships discussed. We further evaluate how well representative P2P MMOG architectures fulfil the design criteria.

A collaborative analysis tool for visualisation and interaction with spatial data

A collaborative virtual environment system is described that is designed to support location-independent shared analysis of spatial data and urban planning proposals. The system seeks to extend the physical workplace of participants into the virtual environment, while preserving traditional textual and verbal communication and cooperation mechanisms. The systems aim is to improve productivity, quality and achieve more transparency in the planning process. The architecture of the Collaborative Urban Planner or CUP system is described and some experimental results that demonstrate urban development control tasks performed within this environment are presented. An application scenario offers a vision of future urban planning practice using CUP. The scenario also diagrammatically demonstrates virtual settings and scenes that could become everyday meeting places for remote planners, architects or engineers assessing proposals and discussing possible alterations to designs.

Practical throughput estimation for parallel databases

Methods for estimating the performance of database management systems can aid the design of database systems by identifying potential performance bottle-necks or by predicting the relative performance of different designs. Performance estimation is critical in parallel database systems with distributed memory, where an effective overall performance depends on a good choice among a wide range of ways of placing data. An approach is described for performance estimation for shared-nothing parallel database systems. It estimates system throughput for a given benchmark or set of queries, and can exercise different data placement schemes to determine the data layout that provides the best throughput value.

An analytical tool for predicting the performance of parallel relational databases

The uptake of parallel DBMSs is being hampered by uncertainty about the impact on performance of porting database applications from sequential to parallel systems. The development of tools which aid the system manager or machine vendor could help to reduce this problem. This paper describes an analytical tool which determines the performance characteristics (in terms of throughput, resource utilisation and response time) of relational database transactions executing on particular machine configurations and provides simple graphical visualisations of these to enable users to obtain rapid insight into particular scenarios. The problems of handling different parallel DBMSs are illustrated with reference to three systems – Ingres, Informix and Oracle. A brief description is also given of two different approaches used to confirm the validity of the analytical approach on which the tool is based. Copyright

Cache modelling in a performance evaluator for parallel database systems

Cache modelling is an important issue in developing an analytical performance evaluator to estimate the performance of applications running on parallel DBMSs. This paper describes a cache model developed for parallel cache management in the Oracle7 parallel server. Some preliminary results have also been obtained by using the cache model to predict the cache hit ratio for varying database sizes and varying numbers of participating processing elements.

Interactive urban development control with collaborative virtual environments

This paper presents the rationale and design for a collaborative virtual environment that is being developed to aid shared assessment of urban planning proposals. The research aims to show how a collaborative virtual environment, system can be constructed, applied and used in the context of urban planning. A navigable and interactive collaborative virtual environment is being created in which planning information is embedded and analytical tools are provided Sharing the virtual experience can improve the collaboration among the planning officers, applicant, engineers, developers and the public. These participants can use the system to explore alternative designs independent of time and place. The system will be suitable for discussions during the development plan and development control (decision-making) process. The system aims to improve communication amongst the involved parties and in turn enhance the quality of decisions made by a planning committee. Better informed decisions will increase the confidence that the public has in the urban development process. The research aims to analyse the usability of a collaborative virtual environment system, not only in terms of its visual and communicative impact, but also its impact on the decision-making process.

Verifying a Performance Estimator for Parallel DBMSs

Although database systems are a natural application for parallel machines, their uptake has been slower than anticipated. This problem can be alleviated to some extent by the development of tools to predict the performance of parallel database systems and provide the user with simple graphic visualisations of particular scenarios. However, in view of the complexities of these systems, verification of such tools can be very difficult. This paper describes how both process algebra and simulation are being used to verify the STEADY parallel DBMS performance estimator.

Identity Support in a Security and Trust Service for Ad Hoc M-commerce Trading Systems

Ad hoc m-commerce is an emerging way of conducting online trading wirelessly within dynamic network communities. However, participants in such systems are vulnerable to attacks on identity establishment such as spoofing and whitewashing as part of fraudulent and unfair trading practices. This paper presents a scheme for identity support using PGP certificates in a fully self-organised manner, where a trading pseudonym and photograph are used as identity credentials. It lets participating parties collaborate in a Peer-to-Peer (P2P) way to establish their online identity in a manner that is resistant to such attacks without any mediation of a Certification Authority (CA). It also lets participating parties handle the security settings of the trading system as well as share knowledge about fellow participants’ trading behaviour without relying on support from a network service provider.

A tool for supporting the teaching of parallel database systems

Parallel database systems are complex entities. When teaching about these systems as part of a course in a limited time, one has difficulty providing useful practical experience that gives a deep insight into system behavior and operation. This paper describes a tool for performance prediction that has been developed to aid the visualization of parallel database systems and that is currently being used to support teaching. The tool enables students to experiment with different hardware and software configurations and to view the effects of changes on the performance of the system. The tool provides insight into how data can be placed among the nodes of a parallel machine according to predefined strategies, as well as manually, and provides feedback on the effect of these on throughput and response time. This tool is able to provide a good appreciation of the concepts in a relatively short period of time.