SUMMARY Current distributed publish/subscribe systems consider all participants to have similar QoS requirements and contribute equally to the system's resources. However, in many real‐world applications, the message delay tolerance of individual participants may differ widely. Disseminating messages according to individual delay requirements not only allows for the satisfaction of user‐specific needs, but also significantly improves the utilization of the resources that participants contribute to a publish/subscribe system. In this article, we propose a peer‐to‐peer‐based approach to satisfy the individual delay requirements of subscribers in the presence of bandwidth constraints. Our approach allows subscribers to dynamically adjust the granularity of their subscriptions according to their bandwidth constraints and delay requirements. Subscribers maintain the overlay in a decentralized manner, exclusively establishing connections that satisfy their individual delay requirements, and that provide messages exactly meeting their subscription granularity. The evaluations show that for many practical workloads, the proposed publish/subscribe system can scale up to a large number of subscribers and performs robustly in a very dynamic setting. Copyright © 2011 John Wiley & Sons, Ltd.

Current distributed publish/subscribe systems assume that all participants have similar QoS requirements and equally contribute to the system's resources. However, in many real-world applications, the message delay tolerance of individual peers may differ widely. Disseminating messages according to individual delay requirements not only allows for the satisfaction of user-specific needs but also significantly improves the utilization of the resources in a publish/subscribe system. In this paper, we propose a peer-to-peer-based approach to satisfy the individual delay requirements of subscribers in the presence of bandwidth constraints. Our approach allows subscribers to dynamically adjust the granularity of their subscriptions according to their bandwidth constraints and delay requirements. Subscribers maintain the publish/subscribe overlay in a decentralized manner by establishing connections to peers that provide messages meeting exactly their subscription granularity and complying to their delay requirements. Evaluations show that for practical workloads, the proposed system scales up to a large number of subscribers and performs robustly in a very dynamic setting. This work was partially funded by the SpoVNet project of Baden-Wurttemberg Stiftung gGmbH.

Abstract. In the context of large decentralized many-to-many communication systems it is impractical to provide realistic and hard bounds for certain QoS metrics including latency bounds. Nevertheless, many applications can yield better performance if such bounds hold with a given probability. In this paper we show how probabilistic latency bounds can be applied in the context of publish/subscribe. We present an algorithm for maintaining individual probabilistic latency bounds in a highly dynamic environment for a large number of subscribers. The algorithm consists of an adaptive dissemination algorithm as well as a cluster partitioning scheme. Together they ensure i) adaptation to the individual latency requirements of subscribers under dynamically changing system properties, and ii) scalability by determining appropriate clusters according to available publishers in the system.

Novel Internet applications demand global availability of complex services that can adapt dynamically to application requirements. At the same time, pervasive Internet usage and heterogeneous access technologies impose new challenges for service deployment. We present Spontaneous Virtual Networks (SpoVNet), a methodology that enables easy development of new services with transparent support for mobility, multi-homing, and heterogeneous environments. This article presents the overlay-based architecture of SpoVNet that supports the spontaneous deployment of new services as well as a seamless transition towards future networks. SpoVNet´s architecture offers support for the underlay aware adaptation of overlays by the use of cross-layer information. In the context of two exemplary services like a group communication service and an event service as well as two demanding applications – a realtime online game and a video streaming application – we illustrate how SpoVNet is of value in establishing services and applications for the Next Generation Internet.

Distributed cooperative systems that use event notification for communication can benefit from event correlation within the notification network. In the presence of uncertain data, however, correlation results easily become unreliable. The handling of uncertainty is therefore an important challenge for event correlation in distributed event notification systems. In this paper, we present a generic correlation model that is aware of uncertainty. We propose uncertainty constraints that event correlation can take into account and show how they can lead to higher confidence in the correlation result. We demonstrate that the application of this model allows to obtain a qualitative description of event correlation.

Novel peer-to-peer-based multiplayer online games are instantiated in an ad-hoc manner without the support of dedicated infrastructure and maintain their state in a distributed manner. Although their employed communication paradigms provide efficient access to sections of distributed state, such communication fails if the participants need to access large subsets of the application state in order to detect high-level situations. We propose a demonstration that shows how multiplayer online games can benefit from using publish/subscribe communication and complex event processing alongside their traditional communication paradigm.

In recent years peer-to-peer (P2P) networking has gained high popularity for large-scale content distribution. Prominent systems expect a large user base with rather diversified demands. Yet it is highly challenging to achieve scalability without sacrificing the expressiveness of queries in such systems. This paper proposes distributed spectral cluster management, an approach which adapts the techniques from spectral graph theory to work in distributed settings. The proposed approach is applied to content-based publish/subscribe to i) significantly reduce the cost for event dissemination by clustering subscribers exploiting the similarity of events, ii) preserve the expressiveness of the subscription language, and iii) perform robustly in the presence of workload variations. The evaluations analyze the accuracy of the proposed distributed spectral mechanisms and show their effectiveness to significantly reduce the efforts to disseminate events under many practical workloads.

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