Kerry Jean

Self-Management of Context-Aware Overlay Ambient Networks

Ambient networks (ANs) are dynamically changing and heterogeneous as they consist of potentially large numbers of independent, heterogeneous mobile nodes, with spontaneous topologies that can logically interact with each other to share a common control space, known as the ambient control space. ANs are also flexible i.e. they can compose and decompose dynamically and automatically, for supporting the deployment of cross-domain (new) services. Thus, the AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. We advocate the use of service specific overlay networks in ANs, that are created on-demand according to specific service requirements, to deliver, and to automatically adapt services to the dynamically changing user and network context. This paper presents a self-management approach to create, configure, adapt, contextualise, and finally teardown service specific overlay networks.

Self-organising Management Overlays for Future Internet Services

Networks are becoming service-aware implying that all relevant business goals pertaining to a service are fulfilled, and also the network resources are used optimally. Future Internet Networks (FIN) have time varying topology (e.g. such networks are envisaged in Autonomic Internet [1], FIND program [2], GENI program [3], FIRE program [4], Ambient Networks [5], Ad-hoc networks [6]) and service availability and service context change as nodes join and leave the networks. In this paper we propose and evaluate a new self-organising service management system that manages such changes known as the Overlay Management Backbones (OMBs). The OMB is a self-organising solution to the problem space in which each OMB node is dynamically assigned a different service context task. The selection of OMB nodes is conducted automatically, without the need of relatively heavy-weighted dynamic negotiations. Our solution relies on the scalability and dynamicity advantages of Distributed Hash Tables (DHTs). This system is needed to select continuously, automatically, and dynamically a set of network nodes, to become responsible for collecting the availability information of service context in the changing network. This solution advances the state of the art avoiding dynamic negotiations between all network nodes reducing management complexity and cost for bandwidth-limited environments.

Towards distributed hash tables (De)composition in ambient networks

When different wireless networks come in close proximity there is often a need for them to logically combine, or compose. We focus on a known research problem particularly in Ambient Networks (ANs), where hetero-geneous Distributed Hash Tables (DHTs) contained in these wireless networks need to merge or divide as a result of these dynamic (de)composition processes, respectively. We present two novel DHT (de)composition models for ANs, known as absorption and gatewaying, that are designed to handle (de)composition of DHTs in different AN network environments, with minimal disturbance to existing member nodes.

Service-aware Overlay Adaptation in Ambient Networks

Developing service-aware self-adaptation systems in heterogeneous and rapidly changing wireless networks such as ambient networks is a challenging issue. Key research areas are adaptation policy definition, network context monitoring, and adaptation policy enforcement. In this paper, we present the ambient virtual pipe platform (AVPP) - that provides a flexible approach towards the creation and management of self-adaptation service-aware overlays in ambient networks

Stochastic maintenance of overlays in structured P2P systems

Peer-to-peer networks have widespread and got commonly used in our every day life. The maintenance strategy of overlays is a key factor in structured peer-to-peer networks. Most of these routing overlays scale well even for a very large number of nodes in static and quasi-static networks. However, providing good performance in dynamic network environments is still an open question. We analyse maintenance of routing overlays in structured P2P systems under churn. We exploit the inherent difference in the role of local (short-range) and long-range connections. We propose a dual strategy for the routing overlays: (i) we reuse strict, proactive and self-stabilizing short-range connection maintenance and (ii) we define a novel, loose and stochastic long-range connection maintenance mechanism, which can significantly reduce maintenance overhead in large networks with high churn rates without affecting routing performance. We use Kleinbergs small worlds model to describe and (re)construct long-range connections. We formally describe the evolution of our proposed system under churn by a Markov chain model and we derive its steady state maintenance traffic (overhead). We formally show that our maintenance method scales logarithmically with the systems size, which is the theoretical lower bound for maintenance traffic to ensure connectivity of the network. Finally, we numerically analyse overlay and maintenance behaviour using various protocol parameter settings and conclude that an overlay with our maintenance method is stable at very high levels of churn.

Autonomic Management of Context-Aware Ambient Overlay Networks

Ambient networks (ANs) introduce a new dynamic and flexible architecture for fixed and mobile networks. The environment is dynamic since they consist of various mobile nodes and flexible since ANs can compose and decompose dynamically and automatically with other ANs. The AN architecture must be sophisticatedly designed to support such high level of dynamicity, heterogeneity and flexibility. Composition and decomposition is performed at the network-level but since the network topology may change, the service delivery should also be adapted accordingly. Indeed, new services should be user-centric. In this paper, for delivering services adapted to the dynamically changing user and network context, we promote the use of service specific overlay networks in ANs that are created on- demand according to specific service requirements. This paper presents an autonomic approach to create, configure, adapt, contextualize, and finally teardown those context-aware overlay networks.

Framework for managing context-aware multimedia services in pervasive environments

This paper presents the CONTEXT framework for the creation, deployment and management of context-aware multimedia services using programmable network facilities. The Service Creation Layer (SCL) components of this framework allow the creation of the services using a service subscription server. Customisation and management are both supported by the policy-based paradigm. The Policy-Based Service Management (PBSM) layer components ensure efficient delivery and management of these services and the Execution Layer components guarantee the correct execution and assurance of the context-aware multimedia services over the network.

Context-Aware GRID Services: Issues and Approaches

While Grid services introduce efficiency in addressing the changing and often large resource demands of Grid applications, making the system context-aware takes the approach a step further by incorporating the important aspects of customisation and personalisation into Open Grid Services Architecture (OGSA) services. This is achieved by extending the concept of virtual organisations (VO) to Grid context, which link context information to users, policies and resources. Context is defined as any information that can be used to characterise the situation of an entity. When this information is modelled and properly managed, the OGSA services can become context-aware and context-aware services can be offered by the Grid.

Towards a Context Monitoring System for Ambient Networks

This paper presents a novel network context monitoring system, known as the context monitoring system (CMS), that is designed to accommodate the rapidly changing network context requirements and network context availability in dynamically (de)composing ambient networks (ANs). CMS is designed to support dynamic deployment, activation, and (re)configuration of context sensors in ANs in an efficient and scalable way, and to locate available distributed network context in a scalable and distributed manner once context sensors are deployed, in order to support subsequent efficient and scalable network context retrieval.

Network-centric context-aware service over integrated WLAN and GPRS networks

In order to bring together the higher speed of WLAN and the wider coverage of GPRS, solution from services perspective is necessary. And this kind of integrated service should be context-aware in order to automatically adapt itself to the changing environment. This paper proposes to explore the applicability of using network-centric context-aware service to integrate WLAN and GPRS network environments. Starting from typical scenario description and requirement analysis, a policy-based context model is presented, which takes into account the real implementation of context-aware service in the underlying networks. A context-aware service scenario called modern professor is explored to exemplify this methodology based on the policy-based context-aware service system architecture.