Context-aware computing envisions a new generation of smart applications that have the ability to perpetually sense the user’s context and use these data to make adaptation decision in response to changes in the user’s context so as to provide timely and personalized services anytime and anywhere. Unlike the traditional distribution systems where the network topology is fixed and wired, context-aware computing systems are mostly based on wireless communication due to the mobility of the network nodes; hence the network topology is not fixed but changes dynamically in an unpredictable manner as nodes join and the leave network, in addition to the fact that wireless communication is unstable. These factors make the design and development of context-aware computing systems much more challenging, as the system requirements change depending on the context of use. The Unified Modelling Language (UML) is a graphical language commonly used to specify, visualize, construct, and document the artefacts of software-intensive systems. However, UML is an all-purpose modelling language and does not have notations to distinguish context-awareness requirements from other system requirements. This is critical for the specification, visualization, construction and documentation of context-aware computing systems because context-awareness requirements are highly important in these systems. This thesis proposes an extension of UML diagrams to cater for the specification, visualization, construction and documentation of context-aware computing systems where new notations are introduced to model context-awareness requirements distinctively from other system requirements. The contributions of this work can be summarized as follows: (i) A context-aware use case diagram is a new notion which merges into a single diagram the traditional use case diagram (that describes the functions of an application) and the use context diagram, which specifies the context information upon which the behaviours of these functions depend. (ii) A Novel notion known as a context-aware activity diagram is presented, which extends the traditional UML activity diagrams to enable the representation of context objects, context constraints and adaptation activities. Context constraints express conditions upon context object attributes that trigger adaptation activities; adaptation activities are activities that must be performed in response to specific changes in the system’s context. (iii) A novel notion known as the context-aware class diagram is presented, which extends the traditional UML class diagrams to enable the representation of context information that affect the behaviours of a class. A new relationship, called utilisation, between a UML class and a context class is used to model context objects; meaning that the behaviours of the UML class depend upon the context information represented by the context class. Hence a context-aware class diagram is a rich and expressive language that distinctively depicts both the structure of classes and that of the contexts upon which they depend. The pragmatics of the proposed approach are demonstrated using two real-world case studies.

Different computation problem domains such as sorting, matrix multiplication, etc. usually require different data representations and algorithms variants implementations in order to be adapted and re-designed to context-aware composition (CAC). Context-aware composition is a technique for the design of applications that can adapt its behavior according to changes in the program. We considered two application domains: matrix multiplication and graph algorithms (DFS algorithm in particular). The main problem in the implementation of the representation mechanisms applied in these problem domains is time spent on the data representation conversion that in the end should not influence the application performance.        This thesis work presents a flexible aspect-based architecture that includes the data structure representation adaptation in order to reduce implementation efforts required for adaptation different application domains.      Although, manual approach has small overhead 4-10% for different problems compared to the AOP-based approach, experiments show that the manual adaptation to CAC requires on average three times more programming effort in terms of lines of code than AOP-based approach. Moreover, the AOP-based approach showed the average speed-up over baseline algorithms that use standard data structures of 2.1.

There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario.

Recommender systems support online customers by suggesting products and services of likely interest to them. Research in recommender systems is now starting to recognise the importance of multiple selection criteria and the role of customer context in improving the recommendation output. This thesis investigates the inclusion of criteria and context information in the recommendation process. Firstly, a novel technique for multi-criteria recommendation is proposed. It assumes that some selection criteria for an item (product or a service) will dominate the overall rating, and that these dominant criteria will be different for different users. Following this assumption, users are clustered based on their criteria preferences, creating a “preference lattice”. The recommendation output for a user is then based on ratings by other users from the same or nearby clusters. Secondly, a context similarity metric for context aware recommendation is presented. This metric can help improve the prediction accuracy in two ways. On the one hand, the metric can guide the aggregation of the feedback from similar context to improve the prediction accuracy. This aggregation is important because the recommendation generation based on prior feedback by similar customers reduces the quantum of feedback used, resulting in a reduction in recommendation quality. On the other hand, the value returned by the context similarity metric can also be used to indicate the importance of the context information in the prediction process for a context aware recommendation.The validation of the two proposed techniques and their applications are conducted in the service domain because the relatively high degree of user involvement attracts users to provide detailed feedback from multiple perspectives, such as from criteria and context perspectives. In particular, hotel services and web services areas are selected due to their different levels of maturity in terms of users’ feedback. For each area, this thesis proposes a different recommendation approach by combining the proposed techniques with a traditional recommendation approach. The thesis concludes with experiments conducted on the datasets from the two aforementioned areas to evaluate the proposed techniques, and to demonstrate the process and the effectiveness of the techniques-based recommendation approaches.

Context-aware computing requires software that can adapt to changes in context. When contextual circumstances trigger multiple adaptations, software must also understand the relationships between these adaptations and react according to the rules governing these relationships. Adaptable software needs a means to establish and interpret these rules in order to avoid any undesirable and potentially catastrophic conflicts. This dissertation designs and implements the Adaptation Rules Management API (ArmAPI). ArmAPI has been demonstrated to work with a Context-Oriented Programming variation for Java called ContextJ* to execute conflict-free adaptations in two software applications. ArmAPI allows programmers to define relationship types between adaptations, and transfers these definitions to Prolog facts and rules. The Prolog engine, encapsulated within ArmAPI, then works with imperative algorithms to determine the appropriate adaptations to execute based on the current set of facts, rules, and contextual circumstances. Context represents all of the conditions for all of the entities known to an observing device. In any environment, context represents a large amount of data that can influence a multitude of conflicting adaptations. This research provides an incremental step towards overcoming the problem of adaptation conflict by constructing an API that considers the relationship types of inclusion, exclusion, ordering, conditional dependency, and independence. The API has been validated via two prototypes that provide typical scenarios.

This dissertation is composed of research studies that contribute to three research areas including social context-aware computing, internal context-aware computing, and human behavioral data mining. In social context-aware computing, four studies are conducted. First, mobile phone user calling behavioral patterns are characterized in forms of randomness level where relationships among them are then identified. Next, a study is conducted to investigate the relationship between the calling behavior and organizational groups. Third, a method is presented to quantitatively define mobile social closeness and social groups, which are then used to identify social group sizes and scaling ratio. Last, based on the mobile social grouping framework, the significant role of social ties in communication patterns is revealed. In internal context-aware computing, two studies are conducted where the notions of internal context are intention and situation. For intentional context, the goal is to sense the intention of the user in placing calls. A model is thus presented for predicting future calls envisaged as a call predicted list (CPL), which makes use of call history to build a probabilistic model of calling behavior. As an incoming call predictor, CPL is a list of numbers/contacts that are the most likely to be the callers within the next hour(s), which is useful for scheduling and daily planning. As an outgoing call predictor, CPL is generated as a list of numbers/contacts that are the most likely to be dialed when the user attempts to make an outgoing call (e.g., by flipping open or unlocking the phone). This feature helps save time from having to search through a lengthy phone book. For situational context, a model is presented for sensing the user's situation (e.g., in a library, driving a car, etc.) based on embedded sensors. The sensed context is then used to switch the phone into a suitable alert mode accordingly (e.g., vibrate mode while in a library, handsfree mode while driving, etc.). Inferring (social and internal) context introduces a challenging research problem in human behavioral data mining. Context is determined by the current state of mind (internal), relationship (social), and surroundings (physical). Thus, the current state of context is important and can be derived from the recent behavior and pattern. In data mining research area, therefore, two frameworks are developed for detecting recent patterns, where one is a model-driven approach and the other is a data-driven approach.

A Computação Ubíqua está revolucionando a interação do ser-humano com os dispositivos computacionais ao disponibilizar tecnologias pouco intrusivas ao cotidiano das pessoas. A Computação Ciente de Contexto, um dos temas de pesquisa em Computação Ubíqua, tem contribuído para a construção de aplicações capazes de customizar-se e adaptar-se às necessidades do usuário sem a intervenção explícita deste. Suportar o desenvolvimento de aplicações Cientes de Contexto é um dos desafios da Computação Ubíqua. Desenvolvido no mesmo grupo de pesquisa que este trabalho está inserido, o Serviço Web Context Kernel, gerencia informações de contexto e explora as especificações e tecnologias da Web como plataforma de intercâmbio para a informação contextual. O trabalho aqui reportado teve como objetivo investigar a utilização de Serviços Web por meio do emprego da infra-estrutura Context Kernel na integração de aplicações em cenários de trabalho colaborativo e de aprendizado eletrônico. Como resultado, foi elaborado um conjunto de lições aprendidas provenientes do estudo e do emprego das especificações para Serviços Web. Outros resultados foram: as especificações de informações de contexto de grupo e de metadados educacionais em dimensões de contexto e exemplos de utilização do Context Kernel para tornar aplicações cientes de contexto. / Ubiquitous computing has became a revolution in terms of the user-computer interaction by providing technologies that seamlessly integrate themselves to people?s everyday life. Context-aware computing, which is an important research theme in ubiquitous computing, has been contributing for the building of applications that are capable both to customize and adapt themselves aiming to support a user without disturb him. A great challenge in ubiquitous computing has been the support to build context-aware aplications. For that reason, the it has been developed the Context Kernel Web Service, which is a service infrastructure that makes use of Web-based specifications and technologies in order to promote the management and the interchange of context information. In this work the usage of Web Services was analyzed by using the Context Kernel to integrate applications in scenarios of cooperative work and e-learning. As a result, a list of lessons learned was ellaborated with respect to the use and the study of Web Services specifications for context-aware computing. Other results include a context information specifications for metadata about group and educational resources as well as examples of how to use the Context Kernel to leverage applications context-aware.

By exploiting context awareness, traditional applications can be extended to offer better quality or new functions. Utilizing a context-aware infrastructure, a variety of context information is merged and processed to produce information that is useful to applications. Applications exploiting such context can provide more intelligent and creative services to end users. This thesis examines two ways to make use of a user’s location along with room occupancy information in context aware applications: a Context Agent and a Call Secretary. In the former case, the application subscribes to room occupancy information via a context server, and provides a Meeting Room Booking System with “real-time” information about the utilization of the rooms which the room booking system is to manage. The Call Secretary acquires both location and room occupancy information from a server. When the user is in one of the meeting rooms and multiple people are present, then this is interpreted as the user being in a meeting -- therefore it triggers a CPL module in a SIP proxy to redirect the user’s incoming call to their voice mail box. A description of the implementation of these two applications will be presented along with an evaluation of these applications’ performance. The evaluation of the Context Agent showed that it was straightforward to integrate information from a presence source and to extend the meeting room booking system to use this information. The Call Secretary needs a more reliable source for the user's location. However, given this location the Call Secretary provides the service which the user expects. / Genom att utnyttja sammanhang medvetenhet, traditionella tillämpningar kan utvidgas till att erbjuda bättre kvalitet eller nya funktioner. Använda en kontextmedvetna infrastruktur, en rad olika kontextuppgifter är sammanslagna och bearbetas för att producera information som är användbar för tillämpningar. Tillämpningar som utnyttjar sådana sammanhang kan ge mer intelligenta och kreativa tjänster till slutanvändare. Denna avhandling undersöker två sätt att använda sig av ett användaren befinner sig längs med rummet beläggningen information i samband medveten program: ett sammanhang av ombud och en uppmaning Sekreterare. I det förra fallet skall ansökan under på rumspris information via ett sammanhang server, och ger ett mötesrum bokningssystem med "realtid" information om användningen av de rum som lokalbokning system är att hantera. Ring sekreterare förvärvar både plats och rumspris information från en server. När användaren är i en av konferenslokaler och flera människor är närvarande, så är det tolkas som att användarna är i ett möte - därför det utlöser en CPL-modul i en SIP-proxy för att dirigera om användarens inkommande samtal till deras telefonsvarare fält. En beskrivning av genomförandet av dessa två program kommer att presenteras tillsammans med en utvärdering av dessa ansökningar resultat. Utvärderingen av det sammanhang ombud visade att det var enkelt att integrera information från en närvaro källa och att utvidga mötesrum bokningssystem att använda denna information. Ring sekreterare behöver en mer tillförlitlig källa för användarens plats. Med tanke på denna plats för samtal sekreterare tillhandahåller tjänster som användaren förväntar sig.

With the rapid development of technology for context awareness, pervasive computing is releasing people from their traditional desktops. Since mobile devices feature portability and are (nearly) always connected, people tend to carry them wherever they go. Hence, devices such as cellular phones and Pocket PCs are the most suitable platforms for developing context aware applications which users will utilize in their daily life. For these context aware systems, using this context information not only improves the user experience of ubiquitous computing, but also lets the system know who you are or what you have. More importantly, the device can know where you are and predict what you might like to do, thus simplifying many of the user’s interactions with devices and other people around them. This thesis project involves the design, implementation and evaluation of a context aware application, based upon a Pocket PC, that can remind the user of tasks when the user approaches the relevant location for this task. The application interacts with a context aware infrastructure by using the SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) protocol, receives context information for the user described using XML. A number of new tags, based upon a new XML schema, have been introduced for this task. This context aware mechanism enables the user to receive any form of information updated by the context server. In this thesis, updates to this information are driven by changes in the user’s location. Additionally, by using the existing calendar application on the Pocket PC, the user can experience location based reminders without learning how to use a new user interface. / Med den snabba utvecklingen av kontextmedvetna teknologier befriar den genomträngande datoriseringen människor från deras traditionella datorer. Eftersom mobila apparater medför bärbarhet och är (nästan) alltid uppkopplade, tenderar människor att bära dem överallt. Följaktligen blir apparater som mobiltelefoner och Pocket-PC de mest passande plattformarna för utvecklandet avkontextmedvetna applikationer för daglig användning. För dessa kontextmedvetna system kommer inte bara användandet av kontexinformation förbättra användarens upplevelse av överallt förekommande datorisering, utan låter även systemet veta vem du är eller vad du har. ännu viktigare är att apparaten kan veta var du befinner dig samt förutsäga vad du skulle kunna vilja göra, och därigenom förenkla mycket av användarens interaktion med andra apparater och människor i omgivningen. Detta examensarbetsprojekt involverar designen, implementationen och evalueringen av en kontextmedvetet applikation, baserad på en Pocket-PC, som kan påminna användaren om uppgifter när användaren närmar sig det relevanta området för dessa uppgifter. Applikationen interagerar med en kontextmedveten infrastruktur genom användandet av protokollet “SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE)”, mottas kontextinformation för användaren beskriven i XML-format. Ett antal nya taggar, baserade på en ny XML-schema, har introducerats för denna uppgift. Denna kontextmedvetna mekanism gör det möjligt för användaren att ta emot alla typer av uppdaterad information från kontextservern. I denna avhandling uppdateras denna information genom att användaren förflyttar sig. Dessutom kan användaren, genom att använda den befintliga kalenderapplikationen i Pocket-PC:n, få lägesbaserade påminnelser skickade till sig utan att behöva lära sig använda ännu ett interface.

Utilizing context information and in networks, enabling network services to act upon context information, and exchanging context information with applications, constitutes an important new approach to designing communication systems and central to the research project named Ambient Networks. The Ambient Networks project is a part of the 6th Framework Project cofunded by the European Commission and carried out by industry and academia. A system is said to be context-aware when it reacts to changes in context i.e., information which describes an entity’s current situation. This new approach enables developments of systems that are more adaptive to user needs and behavior. As a result systems can provide a homogenous appearance which is important as more and more different network access technologies arise. This thesis investigates, models, implements, and evaluates a distributed context-aware architecture for Ambient Networks, the Distributed Context eXchange Protocol (DCXP). The solution is a proof-of-concept that shows how a context-aware ambient network can benefit from a distributed approach. The current design is based on a peer-to-peer architecture that forms an overlay to distribute context information among the participating units. This distributed approach was chosen in order to balance the load and also enable a device to easily locate and fetch desired context information. The evaluation of the proposed context-aware architecture addresses the issues of how such a system ties in with the ideas of Ambient Networks. The main result of this report is a prototype enabling nodes in an ambient network to exchange context information. Moreover, the results show that the prototype needs to be refined in order to work in larger scale networks. / Användning av miljö-beskrivande information, så kallad context information, i olika nätverk är en ny infallsvinkel i designen av kommunikationssystem och är av stor vikt i forskningsprojektet Ambient Networks. Målet är att context information ska kunna utnyttjas i nätverken av olika tjänster samt även dela informationen med applikationer. Ambient Networks projektet är en del av det sjätte EU finansierade ramprogrammet där industrin och den akademiska världen deltar. Ett nätverk eller system klassificeras som context medvetet, context-aware, när det tar hänsyn till förändringar i sk. context information. Context information eller miljö-beskrivande information beskriver en enhets nuvarande situation. Detta möjliggör utveckling av system som ”lyssnar” på användaren och anpassar sig efter dess behov och beteende. Ett praktiskt exempel skulle kunna vara att användare upplever det som ett homogent system trots att det finns flera underliggande access teknologier. Den här uppsatsen undersöker, designar, implementerar och utvärderar en distribuerad context-aware arkitektur för Ambient Networks, Distributed Context eXchange Protocol (DCXP). Lösningen visar hur ett ambient network kan nyttja en distribuerad lösning för att hantera context information. Designen bygger på att de deltagande noderna skapar ett virtuellt nät, overlay, för att mellan sig dela på context informationen. Den här lösningen valdes för att balansera belastningen jämt mellan de deltagande noderna samt att på ett enkelt sätt för varje enskild node kunna lokalisera och hämta önskad context information. Utvärdering av den föreslagna lösningen visar på hur den kan integreras med den övriga utvecklingen som skett inom Ambient Networks projektet. Det huvudsakliga resultatet av arbetet är en prototyp som möjliggör för noder i ett ambient nätverk att utbyta context information. Vidare visar även resultatet att prototypen bör vidareutvecklas för att fungera i större sammanhang.