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Introduction to the special issue on context modelling, reasoning and management
Pervasive and Mobile Computing 6 (2010) 159–160
Contents lists available at ScienceDirect
Pervasive and Mobile Computing journal homepage: www.elsevier.com/locate/pmc
Editorial
Introduction to the special issue on context modelling, reasoning and management Context-awareness is a technique for developing pervasive computing applications that are adaptable and capable of acting autonomously on behalf of users. Such applications adapt to changing context information: physical context, computational context and user context/tasks. Development of context-aware applications is complex as there are many software engineering challenges stemming from heterogeneity of context information sources, imperfection of context information, necessity for reasoning on contextual situations that require application adaptations, etc. The goal of easing development of context-aware applications led to research on context information modelling, reasoning and management, and they have been studied for a number of years. Pervasive computing conferences and in particular dedicated workshops (i.e., workshops on Context Modeling and Reasoning 2003–2009 at the conferences on Pervasive Computing and Communication, and Ubiquitous Computing) are attracting a large number of papers related to context modelling, reasoning and management and influence the direction of research in this area. There is already a consensus in the research community that formal modelling of context information, context management techniques, and also models for reasoning on context, are needed. In this special issue, we present state-of-the-art research on context modelling, management and reasoning. The Special Issue editors selected six papers that address a variety of challenges facing developers of context-aware applications. In addition, a survey paper on context modelling and reasoning techniques, written by a number of experts in the field including the Special Issue editors, was externally reviewed and selected for the inclusion in this Special Issue by the Special Issues’ Editor-in-Chief. In this issue the survey is presented first and is followed by six papers that focus on various aspects of developing context-aware applications. In the survey paper entitled ‘‘A Survey of Context Modelling and Reasoning Techniques’’, Bettini et al. precede the survey with a discussion of the requirements that context modelling and reasoning techniques should meet, including the modelling of a variety of context information types and their relationships, of high-level context abstractions describing real world situations using context information facts, of histories of context information, and of uncertainty of context information. This discussion is followed by a description and comparison of (i) current context information modelling techniques, (ii) reasoning on high-level context abstractions, and (iii) various approaches to dealing with uncertainty of context information. The paper also discusses research on hybrid context models. Applications that adapt to their context need to be able to recognize (reason upon) its current situation based on gathered sensor data. Computing devices differ in their computational capacity and some mobile devices have limited computational resources, making them unsuitable for applying many context recognition/reasoning techniques. Könönen et al. compare several classification and automatic feature selection algorithms in the context recognition domain in their paper entitled ‘‘Automatic feature selection for context recognition in mobile devices’’. The main goal of this study is to investigate how much advantage can be achieved by using sophisticated and complex classification methods compared with a simple method that can easily be implemented in mobile devices. In order to ease development of context-aware applications and support reuse of context information, the trend is to develop such applications above the middleware that supports context-aware applications with context information gathering, preprocessing, evaluation/reasoning and dissemination. Various architectures of the middleware for context-aware applications have been designed so far, including a variety of context reasoning techniques that can be used in the middleware. Zhang et al. in their paper ‘‘Enhancing Intelligence and Dependability of a Product Line Enabled Pervasive Middleware’’ present an approach that combines the power of practical reasoning based on ‘‘Beliefs-Desires-Intentions’’ and ontologybased theoretical reasoning in order to improve the intelligence of the middleware. The reasoning is supported by a set of self-management pervasive service ontologies featuring dynamic context, complex context, and self-management rules modelling. Roussaki et al. in the paper ‘‘Optimising Context Data Dissemination and Storage in Distributed Pervasive Computing Systems’’ address the middleware functionality of gathering and managing context information. They elaborate on 1574-1192/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.pmcj.2010.02.001
160
Editorial / Pervasive and Mobile Computing 6 (2010) 159–160
mechanisms for large scale context management systems and address advanced requirements including support for distributed context databases management, efficient query handling, innovative management of mobile physical objects, and optimization strategies for distributed context data dissemination. Context-aware applications are complex to develop and it can be difficult to properly design at once their full functionality. Seng Loke in his paper entitled ‘‘Incremental Awareness and Compositionality: a Design Philosophy for Context-Aware Pervasive Systems’’ addresses this issue by proposing an incremental approach to building context-aware pervasive systems. The approach facilitates a process of a systematic extension over time of the context information and high-level context abstractions modelling real world situations that a system can be aware of. The paper presents a formalism of operators for building context-aware pervasive systems incrementally and in a compositional manner (by combining multiple systems and subsystems), which facilitates reuse in a formal way. The presented formalism can serve as a (i) basis for a scripting language for programming composite systems, and (ii) language for specifying these systems and then reasoning with specifications of these systems. Finally, the complexity of developing context-aware applications can be reduced by providing powerful modelling techniques not only for the context, but also for the application itself. The last two papers of this special issue belong to the area of a model-driven approach. In their paper ‘‘Towards the Model Driven Development of Context-Aware Pervasive Systems’’, Serral et al. introduce a Model Driven Development (MDD) method for developing context-aware pervasive systems. With this method, a context-aware pervasive system can be specified at a high level of abstraction by means of a set of models that describe both the system functionality and the context information. These models are used for automated code generation. Achilleos et al. use the OMG’s Model Driven Architecture (MDA) paradigm in their paper ‘‘Context modelling and a context-aware framework for pervasive service creation: a Model-driven approach’’ to bring context-awareness into service creation via a model-driven technology. The paper demonstrates the benefits of the model-driven approach via the creation of a pervasive museum service and its evaluation using selected software metrics. Due to the years of research in the field of context modelling, reasoning, and management, the modelling and design of context-aware applications have reached a state of maturity. However, many research issues in this field are still open, including heterogeneity of context information, imperfection of context information, complex mapping between raw context data (e.g., sensor readings) and abstract context information required by applications, privacy of context information, limitations and efficiency of reasoning techniques, difficulties of managing and provisioning context information in systems where mobility and disconnections are common, and the need for intelligibility of context-aware adaptations. We hope that this special issue will provide further insight into this field and influence further research in various aspects of context modelling, reasoning and management that will lead to a next level of common understanding facilitating development of usable and evolvable context-aware applications. Jadwiga Indulska ∗ The University of Queensland, Australia E-mail address: [email protected]. Daniela Nicklas Carl von Ossietzky University of Oldenburg, Germany Available online 6 February 2010 ∗ Corresponding editor. Tel.: +61 733652542.
Contents lists available at ScienceDirect
Pervasive and Mobile Computing journal homepage: www.elsevier.com/locate/pmc
Editorial
Introduction to the special issue on context modelling, reasoning and management Context-awareness is a technique for developing pervasive computing applications that are adaptable and capable of acting autonomously on behalf of users. Such applications adapt to changing context information: physical context, computational context and user context/tasks. Development of context-aware applications is complex as there are many software engineering challenges stemming from heterogeneity of context information sources, imperfection of context information, necessity for reasoning on contextual situations that require application adaptations, etc. The goal of easing development of context-aware applications led to research on context information modelling, reasoning and management, and they have been studied for a number of years. Pervasive computing conferences and in particular dedicated workshops (i.e., workshops on Context Modeling and Reasoning 2003–2009 at the conferences on Pervasive Computing and Communication, and Ubiquitous Computing) are attracting a large number of papers related to context modelling, reasoning and management and influence the direction of research in this area. There is already a consensus in the research community that formal modelling of context information, context management techniques, and also models for reasoning on context, are needed. In this special issue, we present state-of-the-art research on context modelling, management and reasoning. The Special Issue editors selected six papers that address a variety of challenges facing developers of context-aware applications. In addition, a survey paper on context modelling and reasoning techniques, written by a number of experts in the field including the Special Issue editors, was externally reviewed and selected for the inclusion in this Special Issue by the Special Issues’ Editor-in-Chief. In this issue the survey is presented first and is followed by six papers that focus on various aspects of developing context-aware applications. In the survey paper entitled ‘‘A Survey of Context Modelling and Reasoning Techniques’’, Bettini et al. precede the survey with a discussion of the requirements that context modelling and reasoning techniques should meet, including the modelling of a variety of context information types and their relationships, of high-level context abstractions describing real world situations using context information facts, of histories of context information, and of uncertainty of context information. This discussion is followed by a description and comparison of (i) current context information modelling techniques, (ii) reasoning on high-level context abstractions, and (iii) various approaches to dealing with uncertainty of context information. The paper also discusses research on hybrid context models. Applications that adapt to their context need to be able to recognize (reason upon) its current situation based on gathered sensor data. Computing devices differ in their computational capacity and some mobile devices have limited computational resources, making them unsuitable for applying many context recognition/reasoning techniques. Könönen et al. compare several classification and automatic feature selection algorithms in the context recognition domain in their paper entitled ‘‘Automatic feature selection for context recognition in mobile devices’’. The main goal of this study is to investigate how much advantage can be achieved by using sophisticated and complex classification methods compared with a simple method that can easily be implemented in mobile devices. In order to ease development of context-aware applications and support reuse of context information, the trend is to develop such applications above the middleware that supports context-aware applications with context information gathering, preprocessing, evaluation/reasoning and dissemination. Various architectures of the middleware for context-aware applications have been designed so far, including a variety of context reasoning techniques that can be used in the middleware. Zhang et al. in their paper ‘‘Enhancing Intelligence and Dependability of a Product Line Enabled Pervasive Middleware’’ present an approach that combines the power of practical reasoning based on ‘‘Beliefs-Desires-Intentions’’ and ontologybased theoretical reasoning in order to improve the intelligence of the middleware. The reasoning is supported by a set of self-management pervasive service ontologies featuring dynamic context, complex context, and self-management rules modelling. Roussaki et al. in the paper ‘‘Optimising Context Data Dissemination and Storage in Distributed Pervasive Computing Systems’’ address the middleware functionality of gathering and managing context information. They elaborate on 1574-1192/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.pmcj.2010.02.001
160
Editorial / Pervasive and Mobile Computing 6 (2010) 159–160
mechanisms for large scale context management systems and address advanced requirements including support for distributed context databases management, efficient query handling, innovative management of mobile physical objects, and optimization strategies for distributed context data dissemination. Context-aware applications are complex to develop and it can be difficult to properly design at once their full functionality. Seng Loke in his paper entitled ‘‘Incremental Awareness and Compositionality: a Design Philosophy for Context-Aware Pervasive Systems’’ addresses this issue by proposing an incremental approach to building context-aware pervasive systems. The approach facilitates a process of a systematic extension over time of the context information and high-level context abstractions modelling real world situations that a system can be aware of. The paper presents a formalism of operators for building context-aware pervasive systems incrementally and in a compositional manner (by combining multiple systems and subsystems), which facilitates reuse in a formal way. The presented formalism can serve as a (i) basis for a scripting language for programming composite systems, and (ii) language for specifying these systems and then reasoning with specifications of these systems. Finally, the complexity of developing context-aware applications can be reduced by providing powerful modelling techniques not only for the context, but also for the application itself. The last two papers of this special issue belong to the area of a model-driven approach. In their paper ‘‘Towards the Model Driven Development of Context-Aware Pervasive Systems’’, Serral et al. introduce a Model Driven Development (MDD) method for developing context-aware pervasive systems. With this method, a context-aware pervasive system can be specified at a high level of abstraction by means of a set of models that describe both the system functionality and the context information. These models are used for automated code generation. Achilleos et al. use the OMG’s Model Driven Architecture (MDA) paradigm in their paper ‘‘Context modelling and a context-aware framework for pervasive service creation: a Model-driven approach’’ to bring context-awareness into service creation via a model-driven technology. The paper demonstrates the benefits of the model-driven approach via the creation of a pervasive museum service and its evaluation using selected software metrics. Due to the years of research in the field of context modelling, reasoning, and management, the modelling and design of context-aware applications have reached a state of maturity. However, many research issues in this field are still open, including heterogeneity of context information, imperfection of context information, complex mapping between raw context data (e.g., sensor readings) and abstract context information required by applications, privacy of context information, limitations and efficiency of reasoning techniques, difficulties of managing and provisioning context information in systems where mobility and disconnections are common, and the need for intelligibility of context-aware adaptations. We hope that this special issue will provide further insight into this field and influence further research in various aspects of context modelling, reasoning and management that will lead to a next level of common understanding facilitating development of usable and evolvable context-aware applications. Jadwiga Indulska ∗ The University of Queensland, Australia E-mail address: [email protected]. Daniela Nicklas Carl von Ossietzky University of Oldenburg, Germany Available online 6 February 2010 ∗ Corresponding editor. Tel.: +61 733652542.