Evangelos Kotsovinos

Controlling the XenoServer Open Platform

This paper presents the design of the XenoServer Open Platform: a public infrastructure for wide-area computing, capable of hosting tasks that span the full spectrum of distributed programming. The platform integrates resource management, charging and auditing. We emphasize the control-plane aspects of the system, showing how it supports service deployment with a low cost of entry and how it forms a substrate over which other distributed computing platforms can be deployed.

Pinocchio: Incentives for honest participation in distributed trust management

In this paper, we introduce a framework for providing incentives for honest participation in global-scale distributed trust management infrastructures. Our system can improve the quality of information supplied by these systems by reducing free-riding and encouraging honesty. Our approach is twofold: (1) we provide rewards for participants that advertise their experiences to others, and (2) impose the credible threat of halting the rewards, for a substantial amount of time, for participants who consistently provide suspicious feedback. For this purpose we develop an honesty metric which can indicate the accuracy of feedback.

XenoTrust: event-based distributed trust management

This paper describes XenoTrust, the trust management architecture used in the XenoServer Open Platform: a public infrastructure for wide-area computing, capable of hosting tasks that span the full spectrum of distributed paradigms. We suggest that using an event-based publish /subscribe methodology for the storage, retrieval and aggregation of reputation information can help exploiting asynchrony and simplicity, as well as improving scalability.

Managing trust and reputation in the XenoServer open platform

Participants in public distributed computing do not find it easy to trust each other. The massive number of parties involved, their heterogeneous backgrounds, disparate goals and independent nature are not a good basis for the development of relationships through purely social mechanisms. This paper discusses the trust management issues that arise in the context of the XenoServer Open Platform: a public infrastructure for wide-area computing, capable of hosting tasks that span the full spectrum of distributed paradigms. We examine the meaning and necessity of trust in our platform, and present our trust management architecture, named XenoTrust. Our system allows participants of our platform to express their beliefs and advertise them, by submitting them to the system. It provides aggregate information about other participants beliefs, by supporting the deployment of rule-sets, defining how beliefs can be combined. XenoTrust follows the same design principles that we are using throughout the XenoServer project: it provides a flexible platform over which many of the interesting distributed trust management algorithms presented in the literature can be evaluated in a large-scale wide-area setting.

di-jest: Autonomic neighbour management for worm resilience in p2p systems

Internet worms pose a serious and ongoing threat to system security, often resulting in significant service downtime and disruption. In recent years peer-to-peer (p2p) networks have become a target for the deployment of worms as their high connectivity allows for rapid dissemination and homogeneity of the adopted software platform ensures the existence of common susceptibilities. In this paper we observe that peer similarity in p2p networks can greatly increase overall vulnerability; peers with largely different system characteristics are unlikely to be infected by the same worm. With this in mind we present di-jest - an autonomic method for neighbour selection based on heterogeneity. Our results show the efficacy of di-jest in reducing the spread rate and potency of p2p worms. By selecting neighbours with different system characteristics di-jest can reduce the number of peers infected by a worm by up to 80%.

su-chef: Adaptive coordination of intelligent home environments

Traditional recipes are the static products of an empirical, off-line procedure, and contain implicit environmental assumptions, as they are devised based on the exact ingredients and household devices that were available in the environment where they were created. When the parameters of the environment in which a dish is being cooked do not match those of the one in which the corresponding recipe was prepared, frustration is imminent. We present our work on dynamic service composition to facilitate adaptive coordination of smart home environments, and focus on su-chef, an application of these techniques in the cooking domain. We present initial evaluation results demonstrating that our implementation provides a practical and scalable solution

Replic8: location-aware data replication for high availability in ubiquitous environments

File replication for uninterrupted availability is affected by the localised nature of network failures, particularly in ubiquitous, mobile environments; nearby nodes often get disconnected together, as a result of switching equipment faults, or of local wireless network unavailability – for instance, failure of a base station, or loss of network connectivity when a train enters a tunnel. n nIn this paper we propose replic8, a substrate for location-aware file replication, mitigating the effect of localised network failures by storing replicas at network locations selected for being far away. We demonstrate that, compared to storage of replicas at random network locations, replic8 achieves high data availability, and requires lower numbers of replicas to maintain that.