A Survey on Context-aware systems
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paper_title: User interactions with everyday applications as context for just-in-time information access

paper_content:

Our central claim is that user interactions with everyday productivity applications (e.g., word processors, Web browsers, etc.) provide rich contextual information that can be leveraged to support just-in-time access to task-relevant information. We discuss the requirements for such systems, and develop a general architecture for systems of this type. As evidence for our claim, we present Watson, a system which gathers contextual information in the form of the text of the document the user is manipulating in order to proactively retrieve documents from distributed information repositories. We close by describing the results of several experiments with Watson, which show it consistently provides useful information to its users.
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paper_title: The active badge location system

paper_content:

A novel system for the location of people in an office environment is described. Members of staff wear badges that transmit signals providing information about their location to a centralized location service, through a network of sensors. The paper also examines alternative location techniques, system design issues and applications, particularly relating to telephone call routing. Location systems raise concerns about the privacy of an individual and these issues are also addressed.
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paper_title: Context-awareness on mobile devices - the hydrogen approach

paper_content:

Information about the user's environment offers new opportunities and exposes new challenges in terms of time-aware, location-aware, device-aware and personalized applications. Such applications constantly need to monitor the environment - called context - to allow the application to react accordingly to this context. Context-awareness is especially interesting in mobile scenarios where the context of the application is highly dynamic and allows the application to deal with the constraints of mobile devices in terms of presentation and interaction abilities and communication restrictions. Current context-aware applications often realize sensing of context information in an ad hoc manner. The application programmer needs to deal with the supply of the context information including the sensing of the environment, its interpretation and its disposal for further processing in addition to the primary purpose of the application. The close interweavement of device specific context handling with the application obstructs its reuse with other hardware configurations. Recently, architectures providing support for context-aware applications have been developed. Up to now such architectures are not trimmed to the special requirements of mobile devices regarding particularly the limitations of network connections, limited computing power and the characteristics of mobile users. This paper proposes an architecture and a software framework - the hydrogen context framework -which support context-awareness for considering these constraints. It is extensible to consider all kind of context information and comprises a layered architecture. To prove the feasibility the framework has been implemented to run on mobile devices. A context-aware postbox is realized to demonstrate the capabilities of the framework.
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paper_title: Context-Aware Computing : The CyberDesk Project

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The CyberDesk project is aimed at providing a software architecture that dynamically integrates software modules. This integration is driven by a user’s context, where context includes the user’s physical, social, emotional, and mental (focus-of-attention) environments. While a user’s context changes in all settings, it tends to change most frequently in a mobile setting. We have used the CyberDesk system in a desktop setting and are currently using it to build an intelligent home environment.
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paper_title: Towards situated computing

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Situated computing concerns the ability of computing devices to detect, interpret and respond to aspects of the user's local environment. In this paper, we use our recent prototyping experience to identify a number of challenging issues that must be resolved in building wearable computers that support situated applications. The paper is organized into three areas: Sensing the local environment, interpreting sensor data, and realizing the value of situated applications. We conclude that while it is feasible to develop interesting prototypes, there remain many difficulties to overcome before robust systems may be widely deployed.
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paper_title: Placing search in context: the concept revisited

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Keyword-based search engines are in widespread use today as a popular means for Web-based information retrieval. Although such systems seem deceptively simple, a considerable amount of skill is required in order to satisfy non-trivial information needs. This paper presents a new conceptual paradigm for performing search in context, that largely automates the search process, providing even non-professional users with highly relevant results. This paradigm is implemented in practice in the IntelliZap system, where search is initiated from a text query marked by the user in a document she views, and is guided by the text surrounding the marked query in that document (“the context”). The context-driven information retrieval process involves semantic keyword extraction and clustering to automatically generate new, augmented queries. The latter are submitted to a host of general and domain-specific search engines. Search results are then semantically reranked, using context. Experimental results testify that using context to guide search, effectively offers even inexperienced users an advanced search tool on the Web.
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paper_title: Disseminating active map information to mobile hosts

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The article describes an active map service (AMS) that supports context-aware computing by providing clients with information about located-objects and how those objects change over time. The authors focus on the communication issues of disseminating information from an active map server to its clients, and in particular, address how to deal with various overload situations that can occur. Simple unicast callbacks to interested clients work well enough if only a few located-objects are moving at any given time and only a few clients wish to know about any given move. However, if many people are moving about in the same region and many clients are interested in their motion, then the AMS may experience overload due to the quadratic nature of the communications involved. This overload affects both the server as well as any slow communications links being used. Mobile distributed computing enables users to interact with many different mobile and stationary computers over the course of the day. Navigating a mobile environment can be aided by active maps that describe the location and characteristics of objects within some region as they change over time. >
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paper_title: An Infrastructure Approach to Context-Aware Computing

paper_content:

The Context Toolkit (Dey, Abowd, and Salber, 2001 [this special issue]) is only one of many possible architectures for supporting context-aware applications. In this essay, we look at the tradeoffs involved with a service infrastructure approach to context-aware computing. We describe the advantages that a service infrastructure for context awareness has over other approaches, outline some of the core technical challenges that must be addressed before such an infrastructure can be built, and point out promising research directions for overcoming these challenges.
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paper_title: A framework for developing mobile, context-aware applications

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The emergence of truly ubiquitous computing, enabled by the availability of mobile, heterogenous devices that supply context information, is currently hampered by the lack of programming support for the design and development of context-aware applications. We have developed a framework which significantly eases the development of mobile, context-aware applications. The framework allows developers to fuse data from disparate sensors, represent application context, and reason efficiently about context, without the need to write complex code. An event based communication paradigm designed specifically for ad-hoc wireless environments is incorporated, which supports loose coupling between sensors, actuators and application components.
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paper_title: Managing Context Information in Mobile Devices

paper_content:

We present a uniform mobile terminal software framework that provides systematic methods for acquiring and processing useful context information from a user's surroundings and giving it to applications. The framework simplifies the development of context-aware mobile applications by managing raw context information gained from multiple sources and enabling higher-level context abstractions.
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paper_title: Context-awareness on mobile devices - the hydrogen approach

paper_content:

Information about the user's environment offers new opportunities and exposes new challenges in terms of time-aware, location-aware, device-aware and personalized applications. Such applications constantly need to monitor the environment - called context - to allow the application to react accordingly to this context. Context-awareness is especially interesting in mobile scenarios where the context of the application is highly dynamic and allows the application to deal with the constraints of mobile devices in terms of presentation and interaction abilities and communication restrictions. Current context-aware applications often realize sensing of context information in an ad hoc manner. The application programmer needs to deal with the supply of the context information including the sensing of the environment, its interpretation and its disposal for further processing in addition to the primary purpose of the application. The close interweavement of device specific context handling with the application obstructs its reuse with other hardware configurations. Recently, architectures providing support for context-aware applications have been developed. Up to now such architectures are not trimmed to the special requirements of mobile devices regarding particularly the limitations of network connections, limited computing power and the characteristics of mobile users. This paper proposes an architecture and a software framework - the hydrogen context framework -which support context-awareness for considering these constraints. It is extensible to consider all kind of context information and comprises a layered architecture. To prove the feasibility the framework has been implemented to run on mobile devices. A context-aware postbox is realized to demonstrate the capabilities of the framework.
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paper_title: CASS – a middleware for mobile context-aware applications

paper_content:

Among the difficulties faced by designers of mobile context-aware applications is the increased burden of having to deal with context and also the processing and memory constraints of small mobile computers. Although progress has been made in the area of frameworks and toolkits for contextawareness, there is still a need for middleware that supports higher-level context abstractions and is both flexible and extensible in its treatment of
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paper_title: Structuring Context Aware Applications: Five-Layer Model and Example Case

paper_content:

Structuring context aware applications is important for modularising their implementation. The modularization is necessary for re-use and sharing of software and hardware components. For this end, a five-layer model for structuring context aware applications is presented. The layers are Physical, Data, Semantic, Inference and Application. (An example case involving a context aware mobile terminal in various user roles has been devised and implemented and this case is then mapped on to the five-layer model giving an example of its use. NOT DISCUSSED IN THIS POSITION PAPER)
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paper_title: The context toolkit: aiding the development of context-enabled applications

paper_content:

Context-enabled applications are just emerging and promisericher interaction by taking environmental context into account.However, they are difficult to build due to their distributednature and the use of unconventional sensors. The concepts oftoolkits and widget libraries in graphical user interfaces has beentremendously successtil, allowing programmers to leverage offexisting building blocks to build interactive systems more easily.We introduce the concept of context widgets that mediate betweenthe environment and the application in the same way graphicalwidgets mediate between the user and the application. We illustratethe concept of context widgets with the beginnings of a widgetlibrary we have developed for sensing presence, identity andactivity of people and things. We assess the success of ourapproach with two example context-enabled applications we havebuilt and an existing application to which we have addedcontext-sensing capabilities.
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paper_title: An Intelligent Broker Architecture for Context-Aware Systems

paper_content:

Context-aware computing is an emerging paradigm to free everyday users from manually configuring and instructing computer systems. As the general trend of computing is progressing towards an open and dynamic infrastructure, building context-aware systems can be difficult and costly. In order to build successful context-aware systems, we must develop an architecture to reduce the difficulty and cost of building these systems. This PhD. dissertation proposal describes a research plan to develop a broker-centric agent architecture that is aimed to relieve the burden of capability-limited agents of acquiring and reasoning about contexts, and to protect the privacy of users in a contextaware environment. The implementation of the Context Broker Archiecture will explore Web Ontology Language for modeling contexts and privacy policies, Jess for building a hybrid reasoning mechanism and JADE/FIPA for realizing broker behaviors and agent communications.
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paper_title: Managing Context Information in Mobile Devices

paper_content:

We present a uniform mobile terminal software framework that provides systematic methods for acquiring and processing useful context information from a user's surroundings and giving it to applications. The framework simplifies the development of context-aware mobile applications by managing raw context information gained from multiple sources and enabling higher-level context abstractions.
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paper_title: An ontology for mobile device sensor-based context awareness

paper_content:

In mobile computing, the efficient utilisation of the information gained from the sensors embedded in the devices is difficult. Instead of using raw measurement data application specifically, as currently is customary, higher abstraction level semantic descriptions of the situation, context, can be used to develop mobile applications that are more usable. This article introduces an ontology of context constituents, which are derived from a set of sensors embedded in a mobile device. In other words, a semantic interface to the sensor data is provided. The ontology promotes the rapid development of mobile applications, more efficient use of resources, as well as reuse and sharing of information between communicating entities. A few mobile applications are presented to illustrate the possibilities of using the ontology.
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paper_title: The anatomy of a context-aware application

paper_content:

We describe a sensor-driven, or sentient, platform for context-aware computing that enables applications to follow mobile users as they move around a building. The platform is particularly suitable for richly equipped, networked environments. The only item a user is required to carry is a small sensor tag, which identifies them to the system and locates them accurately in three dimensions. The platform builds a dynamic model of the environment using these location sensors and resource information gathered by telemetry software, and presents it in a form suitable for application programmers. Use of the platform is illustrated through a practical example, which allows a user's current working desktop to follow them as they move around the environment.
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paper_title: E-graffiti: evaluating real-world use of a context-aware system

paper_content:

Abstract Much of the previous research in context-aware computing has sought to find a workable definition of context and to develop systems that could detect and interpret contextual characteristics of an user environment. However, less time has been spent studying the usability of these types of systems. This was the goal of our project. E-graffiti is a context-aware application that detects the user's location on a college campus and displays text notes to the user based on their location. Additionally, it allows them to create notes that they can associate with a specific location. We released E-graffiti to 57 students who were using laptops that could access the campus wireless network. Their use of E-graffiti was logged in a remote database and they were also required to fill out a questionnaire towards the end of the semester. The lessons learned from the evaluation of E-graffiti point to themes other designers of ubiquitous and context-aware applications may need to address in designing their own systems. Some of the issues that emerged in the evaluation stage included difficulties with a misleading conceptual model, lack of use due to the reliance on explicit user input, the need for a highly relevant contextual focus, and the potential benefits of rapid, ongoing prototype development in tandem with user evaluation.
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paper_title: Context-aware mobile communication in hospitals

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A, collaborative handheld system extends the instant messaging paradigm by adding context-awareness to support the intensive and distributed nature of information management within a hospital setting.
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paper_title: Issues for context services for pervasive computing

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Context-aware computing has the potential to greatly alleviate the human attention bottleneck. To facilitate the development of context-aware applications, we envision a context service that provides standardized support for applications. It supports both synchronous queries and asynchronous event notifications. It also addresses privacy concerns by providing controls that allow people to limit the release of their context information.
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paper_title: A policy language for a pervasive computing environment

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We describe a policy language designed for pervasive computing applications that is based on deontic concepts and grounded in a semantic language. The pervasive computing environments under consideration are those in which people and devices are mobile and use various wireless networking technologies to discover and access services and devices in their vicinity. Such pervasive environments lend themselves to policy-based security due to their extremely dynamic nature. Using policies allows the security functionality to be modified without changing the implementation of the entities involved. However, along with being extremely dynamic, these environments also tend to span several domains and be made up of entities of varied capabilities. A policy language for environments of this sort needs to be very expressive but lightweight and easily extensible. We demonstrate the feasibility of our policy language in pervasive environments through a prototype used as part of a secure pervasive system.
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Title: A Survey on Context-aware Systems

Section 1: Introduction
Description 1: Introduce the concept of context-aware systems, their historical background, and significance in enhancing the usability and effectiveness of computing devices through environmental context.

Section 2: Architecture
Description 2: Discuss various architectural designs for context-aware systems, detailing approaches like direct sensor access, middleware-based, and context-server-based systems.

Section 3: Context Models
Description 3: Explain the need for context models to define and store context in a machine-processable form and discuss the essential attributes and desirable properties of flexible and efficient context ontologies.

Section 4: Location-aware Systems
Description 4: Describe the widespread application of location-aware systems, focusing on various infrastructures available for collecting position data and highlighting detailed examples.

Section 5: Context-aware Systems
Description 5: Discuss systems that use multiple types of context data beyond location, combining them to create high-level context objects for more adaptive and user-friendly systems.

Section 6: Context-aware Frameworks
Description 6: Introduce various context-aware frameworks that simplify the development of context-aware applications, highlighting the design decisions and features of each framework.

Section 7: Resource Discovery
Description 7: Cover the mechanisms for discovering and managing sensors in a distributed network, ensuring that appropriate sensors can be dynamically found and utilized.

Section 8: Sensing
Description 8: Discuss approaches to managing different data sources and separating applications from context acquisition concerns through components like widgets and sensor nodes.

Section 9: Context Processing
Description 9: Explain the methods for processing raw context data, including aggregation and interpretation, to provide high-level context abstractions useful for application developers.

Section 10: Historical Context Data
Description 10: Address the importance of maintaining historical context data for trend analysis and future context prediction, along with the memory and storage considerations involved.

Section 11: Security and Privacy
Description 11: Highlight the necessity of protecting sensitive context information and overview the security and privacy mechanisms applied in context-aware systems, including context ownership and access control.

Section 12: Conclusion and Future Work
Description 12: Summarize the survey findings, stressing the importance of standardization in context encoding and communication protocols, and suggest future research directions focusing on service-oriented architectures and web services.