Abstract. Context-awareness is a key concept in ubiquitous computing. But to avoid developing dedicated context-awareness sub-systems for specific application areas there is a need for more generic programming frameworks. Such frameworks can help the programmer to develop and deploy context-aware applications faster. This paper describes the Java Context-Awareness Framework – JCAF, which is a Java-based context-awareness infrastructure and programming API for creating context-aware computer applications. The paper presents the design principles behind JCAF, its runtime architecture, and its programming API. The paper presents some applications of using JCAF in three different applications and discusses lessons learned from using JCAF. 1

Abstract. Next-generation Grid applications will be highly heterogeneous in nature, will run on many types of computer and device, will operate within and across many heterogeneous network types, and must be explicitly configurable and runtime reconfigurable. We refer to this future Grid environment as the “divergent Grid”. In this paper, we propose a “deep middleware ” approach to meeting key requirements of the divergent Grid. Deep middleware reaches down into the network to provide highly flexible network support that underpins a rich, extensible and reconfigurable set of application-level “interaction paradigms ” (such as publish-subscribe, multicast, tuple spaces etc.). In our Gridkit middleware platform, these facilities are encapsulated in two key component frameworks: the interaction framework and the overlay framework, which are the subject of this paper. The paper also evaluates the two frameworks in terms of their configurability (e.g. ability to be profiled for different device types) and reconfigurability (e.g. to self-optimise as the environment changes). 1

Ubiquitous computing is a challenge for the design of middleware.

Pervasive context-aware software is an emerging kind of application. Many of these systems register parts of their context-aware logic in the middleware. On the other hand, most conventional testing techniques do not consider such kind of application logic. This paper proposes a novel family of testing criteria to measure the comprehensiveness of their test sets. It stems from context-aware data flow information. Firstly, it studies the evolution of contexts, which are environmental information relevant to an application program. It then proposes context-aware data flow associations and testing criteria. Corresponding algorithms are given. It uses a prototype testing tool to conduct experimentation on an RFID-based location sensing software running on top of context-aware middleware. The experimental results show that our approach is applicable, effective, and promising.

The complexity and dynamism of modern network raise several challenges in the design and development of communication services. The unbearable costs in configuration and management call for autonomic approaches, in which services are able to selfconfigure and self-adapt their activities without human intervention. The need for ubiquity of service provisioning calls for the capability of services of adapting their behavior depending on the current situation (social and spatial) in which they are used. In this paper, after having discussed the need for innovative approaches facilitating the design, development, and execution of autonomic and situation-aware services, we try to analyze the key features that should underlies such a general approach, proposes a general-purpose architecture centered around the abstraction of “agent communication elements”, and sketch the main research thrusts that should be pursued for the realization of the vision. 1. The Vision The Internet as we know it today will have to become like an immense ecology of composite, highly distributed, pervasive, communication-intensive services [KepC03, Zam05]. Such services should be able to: (i) autonomously detect and organize the knowledge necessary to understand the general context – physical, technological, social, user-specific and request-specific – in which they operate; (ii) self-adapt and self-configure their functioning to get the best from any situation, so as to meet the needs of diverse users in diverse situation without explicit human intervention. These features will enable a wide range of new activities that are simply not possible or

Pervasive computing environments are populated by a large number of heterogeneous and dynamic resources, encompassing devices, services and information sources. This number is set to radically increase in the future; as a result, a mobile device will be able to contact a large number of service providers and sensors that will enable it to perform any task at hand. Moreover, interaction with these services and sensors will be made possible by means of various components, some located on the mobile device, some available for download from remote hosts. We refer to services, sensors and components as resources. In this paper we present Q-CAD, a resource discovery framework that enables pervasive computing applications to discover and select the resource(s) best satisfying the user needs, taking the current execution context and quality-of-service (QoS) requirements into account. The available resources are screened, so that only those suitable to the current execution context of the application will be considered; the shortlisted resources are then evaluated against the QoS needs of the application, and a binding is established to the best available. The paper illustrates how we encode context and QoS information, gives details of the Q-CAD model and of its mapping onto a component-based architecture, and it finally reports on the implementation and on the experimental results. 1

Abstract—Ad hoc networks can be used not only as data carriers for mobile devices but also as providers of a new class of services specific to ubiquitous computing environments. Building services in ad hoc networks, however, is challenging due to the rapidly changing operating contexts, which often lead to situations where a node hosting a certain service becomes unsuitable for hosting the service execution any longer. We propose a novel model of service provisioning in ad hoc networks based on the concept of contextaware migratory services. Unlike a regular service that executes always on the same node, a migratory service can migrate to different nodes in the network in order to accomplish its task. The migration is triggered by changes of the operating context, and it occurs transparently to the client application. We designed and implemented a framework for developing migratory services. We built TJam, a proof-of-concept migratory service that predicts traffic jams in a given region of a highway by using only car-to-car short-range wireless communication. The experimental results obtained over an ad hoc network of personal digital assistants (PDAs) show the effectiveness of our approach in the presence of frequent disconnections. We also present simulation results that demonstrate the benefits of migratory services in large-scale networks compared to a statically centralized approach. Index Terms—Mobile computing, mobile applications, ubiquitous computing, distributed programming, distributed systems. 1

Abstract. This paper describes MobJeX, an adaptive Java based application framework that uses a combination of pre-processing and runtime support to provide transparent object mobility (including AWT and Swing user interface components) between workstations, PDAs and smartphones. Emphasis is placed on the mobility subsystem (MS), a mobile object transport mechanism providing a high level of transparency and portability from the perspective of the system and the developer. The MS is compared to its most similar predecessor FarGo, demonstrating the advantages of the MS in terms of transparency and portability. Furthermore, a series of laboratory tests are conducted in order to quantify the runtime performance of the MS and two other systems, FarGo and Voyager.

The incorporation of context-awareness capabilities into pervasive applications allows them to leverage contextual information to provide additional services while maintaining an acceptable quality of service. These added capabilities, however, introduce a distinct input space that can affect the behavior of these applications at any point during their execution, making their validation quite challenging. In this paper, we introduce an approach to improve the test suite of a context-aware application by identifying contextaware program points where context changes may affect the application’s behavior, and by systematically manipulating the context data fed into the application to increase its exposure to potentially valuable context variations. Preliminary results indicate that the approach is more powerful than existing testing approaches used on this type of application. 1

Abstract. Self-adaptive component-based architectures provide methods and mechanisms to support the dynamic adaptation of their structure under evolving execution context. Dynamic adaptation is particularly relevant in the domain of ubiquitous computing, which is subject to numerous unexpected changes of the execution context. In this paper, we focus on changes in the service provider landscape: business services may dynamically come and go, and their quality of service may vary. We introduce an extension of the MADAM component-based planning framework that optimizes the overall utility of applications when such changes occur. MADAM planning is based on dynamic configuration of component frameworks. The extended planning framework supports seamless configuration of component frameworks based on both local and remote components and services. In particular, components and services can be plugged in interchangeably to provide functionalities defined by the component framework. The extended planning framework is illustrated and validated on a use case scenario.