Nigel Baker

University of the West of England, Bristol, Bristol, England, United Kingdom

Are you Nigel Baker?

Claim your profile

Publications (56)15.09 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The evaluation of context middleware systems is a challenging endeavour. Testbed investigations suffer from an unrealistic environment in terms of number of users, high implementation effort for changes and questionable portability of results. Simulation of middleware systems is complex due to the high abstraction of implementation. This paper contributes towards 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.
    Computing, Networking and Communications (ICNC), 2012 International Conference on; 01/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Journal of Ambient Intelligence and Humanized Computing 01/2012; abs/1202.5519.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    IEEE Communications Surveys &amp Tutorials 01/2012; · 4.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recently there has been much discussion about workflow management for computer-based systems. Workflow management allows business managers to coordinate and schedule activities of organisations to optimise the flow of information or operations between the resources of the organisation. Scientific and engineering applications are also being viewed as potential areas in which the principles of workflow management can be applied. Scientific applications, however, present particular problems of workflow management. Not only do the workflow definitions change frequently [VWW96, ER95] but their refinement may only take place as a result of experimentation as the workflow process itself is followed. For these reasons and others commercial workflow management systems appear to be inadequate for the purposes of managing scientific workflow management applications. The construction of large scale scientific and engineering systems necessitates the use of complex production management operations. The coordination of these operations can be difficult, particularly if the operations are distributed over many geographically separated institutes. In these environments there can be severe constraints both of time and budget so that controlled management of the inherent workflow processes becomes paramount. One example of this scientific development process is the construction of high precision scientific apparatus for high energy physics such as the Compact Muon Solenoid experiment [CMS95] (CMS) currently being undertaken for CERN, the European Centre for Particle Physics research. The construction of CMS is long scale (1998-2004), heavily constrained by resource availability and allocation and very state-of-the-art in nature. A research and development project, entitled CRISTAL (Cooperating Repositories and an Information System for Tracking Assembly Lifecycles) [LeG96], has been initiated to facilitate the management of the engineering data collected at each stage of production of CMS components. This paper reports on the aspects of scientific workflow management and product data management and the interface between the two which have been identified as being central to the assembly and production of the CMS detector.
    07/2011: pages 18-34;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Smart spaces are characterised by availability of information from digital artifacts embedded in the environment and network services that unobtrusively enhance our interaction with the digital world. User and environment context plays a vital role in deciding the usability of information services available in a smart space. Making this context available and coordinating it across the network, geographic and administrative boundaries of individual smart spaces are significant challenges that have not been adequately addressed in existing context-aware systems. We discuss various facets of this challenge and present an architecture based on federation of context brokers for large-scale context dissemination in smart spaces.
    Internet Communications (BCFIC Riga), 2011 Baltic Congress on Future; 03/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Modeling ad-hoc context-aware services and applications that are delivered to a user as they move through a smart space has always been fraught with difficulty. It requires representation, management and inference of context, dynamic update of both context & application domain models, reasoning matching, querying and triggering of services. Quite often these systems comprise of many models and extensive middleware which seems excessive for simple context-aware applications involving mobile and wireless devices. Configuring and triggering services automatically whilst traversing a particular space further compounds the complexity. Part of the problem is finding a conceptual abstraction which is compact and concise yet can inclusively model all the dynamism and expressivity required of such a system. In this paper we propose a Chemical Model inspired by Mendeleev's periodic table that we have experimented with and shows promise in fulfilling these requirements.
    New Technologies, Mobility and Security (NTMS), 2011 4th IFIP International Conference on; 03/2011
  • Source
    Proceedings of the Second Workshop on Context-Systems Design, Evaluation and Optimisation in conjunction with the 24th International Conference on Architecture of Computing Systems (ARCS); 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Supporting context-aware services and applications that are delivered to a user as they move through a smart space is a challenge. The complexity of awareness and interaction requires an efficient interaction and adaptation model. Most research prototypes comprise of many models and extensive middleware which seems excessive for simple context-aware applications involving pervasive devices. Part of the problem is finding a conceptual abstraction which is compact and concise yet can exclusively model all the dynamism and expressivity required for such a system. In this paper we propose a context aware architecture based on a smart space context model and a middleware inspired by chemical reactions.
    Proceedings of the 7th International Wireless Communications and Mobile Computing Conference, IWCMC 2011, Istanbul, Turkey, 4-8 July, 2011; 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mobile devices are increasingly becoming the main mean of interaction for inhabitants of ubiquitous computing environments. Pervasiveness of these devices as users’ personal gadgets and their high-tech capabilities allow capturing of broad contextual information about the physical environment, users social profile and preferences. These modern roles of mobile devices facilitate a number of user and environment related context consuming and producing applications to be hosted on these devices. But without a coordinating component on the mobile device these context consumers and providers are a potential burden on device resources, specifically the effect of uncoordinated computation and communication shortens the battery life. In this paper we briefly describe the concept of a Mobile Context Broker and focus on the energy conservation benefits gained through the context coordination facilities provided by the Mobile Context Broker executing on a smart mobile device. The reported results signify reduction in energy consumption.
    Smart Spaces and Next Generation Wired/Wireless Networking, 11th International Conference, NEW2AN 2011, and 4th Conference on Smart Spaces, ruSMART 2011, St. Petersburg, Russia, August 22-25, 2011. Proceedings; 01/2011
  • Ahsan Ikram, Nigel Baker
    [Show abstract] [Hide abstract]
    ABSTRACT: Awareness is a necessary aspect of interaction of present day devices and communications in pervasive environments. Awareness is dependant on the information of surroundings that is seen as 'Context'. The sources of context have grown exponentially in the recent past and with growing device and sensing capabilities will continue to grow. Pervasive context awareness shares a lot of analogies with chemistry and chemical reactions. In this paper we propose a chemical reaction model based on the assumption of applying chemistry related concepts to context and awareness.
    7th International Conference on Intelligent Environments, IE 2011, Nottingham, United Kingdom, July 25-28, 2011; 01/2011
  • Source
    Proceedings of the 20th Future Network and Mobile Summit; 01/2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dissemination of context data from context producing entities to context consuming entities is a fundamental functional task of context aware systems. Broker based approaches have been successfully demonstrated in a number of prototype context-aware systems. With the increase in sensing capabilities of mobile devices, such devices are not merely consumers of context information any more but also have the ability to be providers of context gathered through integrated sensors. In such a provider-consumer model, where context dissemination is aided by a central broker, device-broker interaction can become a communication and computation bottleneck in presence of multiple context providers and consumers in mobile devices. In this paper we present a theoretical model for a large scale context-aware system based on a federation of multiple context brokers and discuss the concept of a mobile broker to facilitate the participation of mobile devices in context provision and consumption efficiently. The utilisation of an asynchronous event-based publish-subscribe paradigm is focused as a key element.
    Computer and Information Technology (CIT), 2010 IEEE 10th International Conference on; 08/2010
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although PERSIST and C-CAST have different specific objectives they do share a common goal of making use of context and advancing knowledge in building pervasive smart spaces. This paper compares the approaches, analyses the results and considers the outcomes for mobile context-aware services and pervasive computing.
    The Second International Workshop on Information Quality and Quality of Service for Pervasive Computing in Conjunction with IEEE PERCOM 2010; 06/2010
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Context representation is a fundamental process in developing context aware systems for the pervasive world. We present a light weight XML based context representation schema called ContextML in which context information is categorized into scopes and related to different types of entities (e.g. user, device). The schema is also applied for encoding management messages in order to allow for a flexible framework supporting gradual plug & play extendibility and mobility. ContextML is tailored to be used for REST-based communication between the framework components. Explanation of the schema is provided with the help of real world examples. Moreover, the European C-CAST testbed is introduced, embracing a variety of context providers and application domains.
    Wireless Pervasive Computing (ISWPC), 2010 5th IEEE International Symposium on; 06/2010
  • Eike S. Reetz, Ralf Tonjes, Nigel Baker
    [Show abstract] [Hide abstract]
    ABSTRACT: The integration of Wireless Sensor Networks at a global scale is a crucial step on the road to a tighter coupling between the virtual and real world. In a context-aware system with thousands or even millions of data items describing the current situation, it is obvious that this data needs to be filtered and aggregated in order to distribute the detection and processing efficiently. The need to aggregate data exists also from the perspective of the Wireless Sensor Network since energy is limited and there is a strong requirement to reduce communication traffic. Therefore, this paper illustrates the general concept of a context-aware system and explains in detail how to integrate Wireless Sensor Networks in such a system for global usage of information detected by numerous nodes. The concept is proven by implementation, measurements, and a theory of operation.
    Wireless Pervasive Computing (ISWPC), 2010 5th IEEE International Symposium on; 06/2010
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Caching is a well-established mechanism used in distributed systems for improving overall performance. In this paper, we analyse the effect of using a context cache in a broker-based context provisioning system. An experiment is carried out using a simulation based on our framework architecture of context consumers, context broker and context providers exchanging different types of context data over time. The results show notable improvement in the context query response time.
    Smart Sensing and Context - 5th European Conference, EuroSSC 2010, Passau, Germany, November 14-16, 2010. Proceedings; 01/2010
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ubiquitous Systems as envisaged by Mark Weiser are becoming a reality due to recent developments in mobile computing, sensing and wireless connectivity. Numerous context-aware applications and services have been proposed in different domains. Simultaneously, various concepts and models have been introduced as far as management and representation of contextual information are concerned. This paper presents the efforts towards a prototype deployment of a context provisioning framework based on a brokered consumer-provider management model. The testbed covers a variety of context data and can be extended gradually to support emerging and evolving ubiquitous context-aware applications. The performance of the system is evaluated by providing measurement results.
    01/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents the design of a Context Management Architecture. It introduces a modular and extendible management model comprising Context Broker, Context Provider and Context Consumer entities. In addition, Service Enabler components are introduced. By descriptive commercial trials and usage scenarios its success is documented. The architecture proves its ability to support a large variety of contextual information. Hence, it is suited for multi-domain context-aware communication systems and evolves by adding new context scopes during runtime.
    01/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ubiquitous Systems as envisaged by Mark Weiser are becoming a reality due to recent developments in mobile computing, sensing and wireless connectivity. Numerous context-aware applications and services have been proposed in different domains. Simultaneously, various concepts and models have been introduced as far as management and representation of contextual information are concerned. This paper presents the efforts towards a prototype deployment of a context provisioning framework based on a brokered consumer-provider management model. The testbed covers a variety of context data and can be extended gradually to support emerging and evolving ubiquitous context-aware applications. The performance of the system is evaluated by providing measurement results.
    Smart Sensing and Context, 4th European Conference, EuroSSC 2009, Guildford, UK, September 16-18, 2009. Proceedings; 01/2009
  • Source
    Towards the Future Internet - A European Research Perspective; 01/2009