Marcus Handte

PCOM - a component system for pervasive computing

Applications in the pervasive computing domain are challenged by the dynamism in which their execution environment changes, e.g. due to user mobility. As a result, applications have to adapt to changes regarding their required resources. In this paper we present PCOM, a component system for pervasive computing. PCOM offers application programmers a high-level programming abstraction which captures the dependencies between components using contracts. The resulting application architecture is a tree formed by components and their dependencies. PCOM supports automatic adaptation in cases where the execution environment changes to the better or to the worse. User supplied as well as system provided strategies take users out of the control loop while offering flexible adaptation control.

Peer-based automatic configuration of pervasive applications

Pervasive computing envisions seamless support for user tasks through cooperating devices that are present in an environment. Fluctuating availability of devices, induced by mobility and failures, requires mechanisms and algorithms that allow applications to adapt to changing environmental conditions without user intervention. To ease the development of adaptive applications, we have proposed the peer-based component system PCOM. This system provides fundamental mechanisms to support the automated composition of applications at runtime. In this paper, we discuss the requirements on peer-based automatic configuration of pervasive applications and present an approach based on distributed constraint satisfaction. The resulting algorithm configures applications in the presence of strictly limited resources. To show the feasibility of the approach, we have integrated the algorithm into PCOM and provide an evaluation based on simulation and measurements.

Customizable pervasive applications

Human behavior and housing resist every standardization effort. Many aspects such as different technical equipment, furniture, and usage patterns make our surroundings as individual as ourselves. Thus, the personalization of pervasive applications is a fundamental requirement. To enable the development of custom pervasive applications, we propose a software development process. This process is based on the successful process for modern desktop applications. There, developers create extensible applications and components. Customizers use the resulting artifacts to develop custom applications. Finally, users configure applications to their individual needs by adjusting predefined settings. To adopt this process for pervasive computing, we present a component system for developers, a graphical toolkit for customizers, and self-configuration algorithms to ease the deployment

3PC: System support for adaptive peer-to-peer pervasive computing

A major characteristic of pervasive computing applications is their ability to adapt themselves to changing execution environments and physical contexts. In this article, we analyze different kinds of adaptations and introduce a multidimensional classification for them. On this basis, we propose a novel approach for peer-to-peer-based pervasive computing that provides support for the identified classes and integrates them in a multilevel architecture. We give a comprehensive overview of this architecture and its current realization in the Peer-to-Peer Pervasive Computing (3PC) project, discussing what adaptation is realized on each level, how the levels interact with each other, and how the overall system benefits from the integrated treatment of adaptation.

A Coordination Framework for Pervasive Applications in Multi-user Environments

Pervasive applications have been designed to support users in their everyday life. For this purpose, they are able to interact with their physical environment, their context. They are aware of their context and use this information for configuration decisions. Furthermore, they can actively modify the context to meet their user’s needs. This leads to new challenges in multi-user environments as applications which are executed simultaneously share a common context and thus can directly impact each other. In this paper we present a framework to coordinate multiple pervasive applications explicitly considering their context-interactivity. We show how application coordination can be integrated in an existing component-based system exemplified by our system PCOM. We conduct measurements for the extended system and discuss the obtained results.

Pervasive Computing Middleware

Pervasive computing envisions applications that provide intuitive, seamless and distraction-free task support for their users. To do this, the applications combine and leverage the distinct functionality of a number of devices. Many of these devices are invisibly integrated into the environment. The devices are equipped with various sensors that enable them to perceive the state of the physical world. By means of wireless communication, the devices can share their perceptions and they can combine them to accurate and expressive models of their surroundings. The resulting models enable applications to reason about past, present and future states of their context and empower them to behave according to the expectations of the user.

Enabling energy-efficient context recognition with configuration folding

Existing context recognition applications for personal mobile devices are usually fine-tuned to recognize the set of characteristics required to support a particular user task. Outside of a laboratory environment, however, users are often involved in multiple tasks at a time which requires the simultaneous execution of several applications. Yet, due to the energy constraints of most personal mobile devices this approach is inherently limited in scale. In this paper, we show how this problem can be avoided by applying a component-based approach to application development and execution. We present a component system that enables developers to build individual applications in isolation without compromising runtime efficiency. When applications are executed simultaneously, the component system applies a novel technique called configuration folding to automatically remove redundancies. Our experimental evaluation of configuration folding shows that it can save up to 48 percent of energy when applied to a music and a speech detection application, thus, amortizing energy costs after a few seconds of execution.

Generic role assignment: A uniform middleware abstraction for configuration of pervasive systems

Pervasive computing envisions distraction-free support for user tasks by means of cooperating devices that are invisibly integrated into the environment. Due to device mobility and continuous changes in context, pervasive systems need to be adaptive to realize this vision. To simplify their development, pervasive computing middleware ease the resulting configuration tasks. In the past, middleware developers have used independent abstractions to support different task. In this paper, we argue that support for the configuration should be built on top of one generic abstraction. For this, we introduce the abstraction of a role and we outline how role assignment can be used to support configuration. Finally, we also show that our approach has additional benefits such as improved reuse of configuration logic and increased flexibility to support novel configuration tasks.

Supporting Pluggable Configuration Algorithms in PCOM

Pervasive computing envisions distributed applications that optimally leverage the resources present in their ever-changing execution environment. To ease the development of pervasive applications, we have created a pervasive component system (PCOM). PCOM automates the configuration and runtime adaptation of a component-based application using a built-in distributed configuration algorithm. In this paper, we present an architectural extension that allows switching between different algorithms. This enables PCOM to dynamically select an algorithm that suits the computational resources present in an environment. To validate the extended architecture, we compare the overheads of a distributed and a centralized configuration algorithm in two different environments

Requirement Considerations for Ubiquitous Integration of Cooperating Objects

Billions of devices are expected to be online by 2020. These will not only provide information by monitoring the real-world, but create complex collaborations in order to provide sophisticated value-added services. Slowly, we are witnessing the emergence of Cooperating Objects in the Internet of Things, which will rapidly change the way we design, develop and realize cyber-physical dependent applications. We investigate which requirements this poses, and evaluate several middleware systems which we have used in the past. Finally we prioritize the requirements, and discuss on future directions that could be followed.