Energy conservation in mobile devices and applications: A case for context parsing, processing and distribution in clouds

Context information consumed and produced by the applications on mobile devices needs to be represented, disseminated, processed and consumed by numerous components in a context-aware system. Significant amounts of context consumption, production and processing takes place on mobile devices and there is limited or no support for collaborative modelling, persistence and processing between device-Cloud ecosystems. In this paper we propose an environment for context processing in a Cloud-based distributed infrastructure that offloads complex context processing from the applications on mobile devices. An experimental analysis of complexity based context-processing categories has been carried out to establish the processing-load boundary. The results demonstrate that the proposed collaborative infrastructure provides significant performance and energy conservation benefits for mobile devices and applications

Survey of context provisioning middleware

In the scope of ubiquitous computing, one of the key issues is the awareness of context, which includes diverse aspects of the user's situation including his activities, physical surroundings, location, emotions and social relations, device and network characteristics and their interaction with each other. This contextual knowledge is typically acquired from physical, virtual or logical sensors. To overcome problems of heterogeneity and hide complexity, a significant number of middleware approaches have been proposed for systematic and coherent access to manifold context parameters. These frameworks deal particularly with context representation, context management and reasoning, i.e. deriving abstract knowledge from raw sensor data. This article surveys not only related work in these three categories but also the required evaluation principles. © 2009-2012 IEEE

A context provisioning middleware with support for evolving awareness

This thesis contributes to the research domain of Ubiquitous and Context-aware Computing. It presents a novel middleware (entitled Context Provisioning Middleware with Support for Evolving Awareness; C- ProMiSE) that applies a consumer-producer role model as architectural basis. The middleware aims at supporting diverse applications and services to easily and coherently acquire relevant context information. A mediat- ing Context Broker facilitates the coordination between distributed Context Provider, Context Source and Context Consumer components. The chosen design principles support' self-management capabilities and modular extendibility during run-time. Communication is based on the Representational State Transfer (REST) approach. Context is represented in ContextML, an XML-based modelling schema, enabling a structured generally applicable basis for various context domains, e.g. spatial, temporal, device-specific and user-centric prop- erties. This combination of context management and context representation model allows for gradual and distributed context processing and reasoning. Context is abstracted in various layers from primitive data up to high-level interpretation, e.g. users' activities. Specific emphasis is put on probabilistic reasoning of data originating from physical, virtual and logical sensors. In addition to the conceptualisation, a specific prototype implementation is presented and utilised as ex- perimentation testbed. Its functional evaluation covers field tests and context emulation. With regard to quantitative evaluation, the C-ProMiSE performance is finally assessed by applying both black-box tests of specific prototype components and Discrete Event Simulation at system level. Focus of the experimen- tation is to estimate the responsive context provisioning behaviour realistically. The obtained results lend weight to the argument that a consumer-producer-broker based framework can serve as basis to realise a distributed multi-domain context provisioning middleware that does not only scale physically but also functionally with regard to context processing capabilities. Furthermore, the con- text management, context representation and context processing concepts allow for supporting a variety of emerging and evolving context-aware applications and services.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Context-aware service utilisation in the clouds and energy conservation

Ubiquitous computing environments are characterised by smart, interconnected artefacts embedded in our physical world that provide useful services to human inhabitants unobtrusively. Mobile devices are becoming the primary tools for human interaction with these embedded artefacts and for the utilisation of services available in smart computing environments such as clouds. Advancements in the capabilities of mobile devices allow a number of user and environment related context consumers to be hosted on these devices. Without a coordinating component, these context consumers and providers are a potential burden on device resources; specifically the effect of uncoordinated computation and communication with cloud-enabled services can negatively impact battery life. Therefore energy conservation is a major concern in realising the collaboration and utilisation of mobile device based context-aware applications and cloud based services. This paper presents the concept of a context-brokering component to aid in coordination and communication of context information between mobile devices and services deployed in a cloud infrastructure. A prototype context broker is experimentally analysed for effects on energy conservation when accessing and coordinating with cloud services on a smart device, with results signifying reduction in energy consumption

Federated broker system for pervasive context provisioning

Software systems that provide context-awareness related functions in pervasive computing environments are gaining momentum due to emerging applications, architectures and business models. In most context-aware systems, a central broker performs the functions of context acquisition, processing, reasoning and provisioning to facilitate context-consuming applications, but demonstrations of such prototypical systems are limited to small, focussed domains. In order to develop modern context-aware systems that are capable of accommodating emerging pervasive/ubiquitous computing scenarios, are easily manageable, administratively and geographically scalable, it is desirable to have multiple brokers in the system divided into administrative, network, geographic, contextual or load based domains. Context providers and consumers may be configured to interact only with their nearest, relevant or most convenient broker. This setup demands inter-broker federation so that providers and consumers attached to different brokers can interact seamlessly, but such a federation has not been proposed for context-aware systems. This article analyses the limiting factors in existing context-aware systems, postulates the design and functional requirements that modern context-aware systems need to accommodate, and presents a federated broker based architecture for provisioning of contextual information over large geographical and network spans

Performance simulation of a context provisioning middleware based on empirical measurements

© 2012 Elsevier B.V. The evaluation of context middleware systems is a challenging endeavour. On the one hand, testbed investigations suffer from an unrealistic environment in terms of number of users, high implementation effort for changes and questionable portability of results. On the other hand simulation of middleware systems is complex due to the high abstraction of implementation. This article contributes to the understanding of a broker based context provisioning system based on black-box measurements of a testbed which are further utilised to increase the accuracy of a simulation model. Both simulations and measurements help in understanding the complex behaviour of a context provisioning middleware and enable the evaluation of complex distributed systems. The presented investigations identify significant parameters and corresponding models for the response delay of the key components of a context provisioning middleware and discuss their integration into an overall simulation model