George A. Papadopoulos

A survey of software adaptation in mobile and ubiquitous computing

Driven by the vast proliferation of mobile devices and ubiquitous computing, dynamic software adaptation is becoming one of the most common terms in Software Engineering and Computer Science in general. After the evolution in autonomic and ubiquitous computing, we will soon expect devices to understand our changing needs and react to them as transparently as possible. Software adaptation is not a new term though; it has been extensively researched in several domains and in numerous forms. This has resulted in several interpretations of adaptation. This survey aims to provide a disambiguation of the term, as it is understood in ubiquitous computing, and a critical evaluation of existing software adaptation approaches. In particular, we focus on existing solutions that enable dynamic software modifications that happen on resource constrained devices, deployed in mobile and ubiquitous computing environments.

A comprehensive context modeling framework for pervasive computing systems

Context management in pervasive computing environments must reflect the specific characteristics of these environments, e.g. distribution, mobility, resource-constrained devices, or heterogeneity of context sources. Although a number of context models have been presented in the literature, none of them supports all of these requirements to a sufficient extent at the same time. In this paper, we present a comprehensive and integrated approach for context modeling in pervasive computing environments. It combines the advantages of existing approaches and addresses the need for supporting effective software development. The proposed context model follows an ontology-based approach and has three layers of abstraction, i.e. conceptual layer, exchange layer, and functional layer. This layered approach facilitates a model-driven development of context-aware applications. Throughout the paper we compare our solution with the related work in order to clearly demonstrate why we needed to develop a new context management framework and where we have adopted existing ideas.

A development framework and methodology for self-adapting applications in ubiquitous computing environments

Today software is the main enabler of many of the appliances and devices omnipresent in our daily life and important for our well being and work satisfaction. It is expected that the software works as intended, and that the software always and everywhere provides us with the best possible utility. This paper discusses the motivation, technical approach, and innovative results of the MUSIC project. MUSIC provides a comprehensive software development framework for applications that operate in ubiquitous and dynamic computing environments and adapt to context changes. Context is understood as any information about the user needs and operating environment which vary dynamically and have an impact on design choices. MUSIC supports several adaptation mechanisms and offers a model-driven application development approach supported by a sophisticated middleware that facilitates the dynamic and automatic adaptation of applications and services based on a clear separation of business logic, context awareness and adaptation concerns. The main contribution of this paper is a holistic, coherent presentation of the motivation, design, implementation, and evaluation of the MUSIC development framework and methodology.

A Context Query Language for Pervasive Computing Environments

This paper identifies requirements for querying and accessing context information in mobile and pervasive computing environments. Furthermore it studies existing query languages showing that they satisfy only a subset of these requirements or cover some of them only to a limited extent. A new context query language is presented to overcome these shortcomings, improving the state of the art in several respects: heterogeneous representations of context information, definition of complex filtering mechanisms, elaborate aggregation functions and ontology integration, all in one language.

Models and technologies for the coordination of Internet agents: a survey

Agent technology has evolved rapidly over the past few years along a number of dimensions giving rise to numerous “flavours” of agents such as intelligent agents, mobile agents, etc. One of the most attractive and natural fields for the development of agent technology is the Internet with its vast quantity of available information and offered services. In fact, the term “Internet agent” is effectively an umbrella for most of the other types of agents, since Internet agents should enjoy intelligence, mobility, adaptability, etc. All these different types of agents must be able to somehow interact with each other for the purpose of exchanging information, collaborating or managing heterogeneous environments. This survey presents some of the most common models and technologies that offer coordination mechanisms for Internet agents. It argues for the need of using coordination, then it presents some basic infrastructure technologies before examining in more detail particular coordination models for Internet agents, themselves classified into some general categories.

A Utility-Based Adaptivity Model for Mobile Applications

Mobile environments are characterized by resource fluctuations and limitations, and variations in user preferences. Therefore mobile applications need to be adaptive to retain usability, usefulness and reliability. In our approach to support adaptivity, we combine context awareness, reflection and component composition planning. The planning is done by generic middleware and supports dynamic discovery, utility-based and context-aware evaluation, and selection of the best implementation alternative of a given mobile application. In this paper we present a formal model of our approach and use this model to show the expressiveness of utility-based adaptation policies. To demonstrate the feasibility and expressiveness of our approach we include a case study based on a real adaptive application built using our model and middleware.

A Pluggable and Reconfigurable Architecture for a Context-Aware Enabling Middleware System

Context awareness is a core feature of modern mobile and ubiquitous computing systems. Although it has not reached its full potential yet, one can already observe significant activity in the area of software engineering for supporting the development of context-aware applications. An example of such an activity is the MUSIC project, which proposes a middleware featuring a generic and reusable context management system. This paper describes the pluggable architecture of this system, and explains how it advances the state of the art through its support for context heterogeneity and better resource utilization. The former is achieved with the use of a novel architecture, which enables the separation of low-level, platform-specific context plug-ins from higher-level application-specific ones. The improved resource utilization is achieved through intelligent activation and deactivation of context plug-ins based on the needs of the active applications. The proposed approach has been experimentally evaluated and the results indicate that it significantly improves the resource utilization in context-aware applications, especially when deployed on lightweight mobile devices.

Aspect Oriented Programming for a component-based real life application: a case study

Aspect Oriented Programming, a relatively new programming paradigm, earned the scientific communitys attention. The paradigm is already evaluated for traditional OOP and component-based software development with remarkable results. However, most of the published work, while of excellent quality, is mostly theoretical or involves evaluation of AOP for research oriented and experimental software. Unlike the previous work, this study considers the AOP paradigm for solving real-life problems, which can be faced in any commercial software. We evaluate AOP in the development of a high-performance component-based web-crawling system, and compare the process with the development of the same system without AOP. The results of the case study mostly favor the aspect oriented paradigm.

Configuration and dynamic reconfiguration of components using the coordination paradigm

Abstract One of the most promising approaches in developing component-based (possibly distributed) systems is that of coordination models and languages. Coordination programming enjoys a number of advantages such as the ability to express different software architectures and abstract interaction protocols, support for multi-linguality, reusability and programming-in-the-large, etc. Configuration programming is another promising approach in developing large scale, component-based systems, with the increasing need for supporting the dynamic evolution of components. In this paper we explore and exploit the relationship between the notions of coordination and (dynamic) configuration and we illustrate the potential of control- or event-driven coordination languages to be used as languages for expressing dynamically reconfigurable software architectures. We argue that control-driven coordination has similar goals and aims with the notion of dynamic configuration and we illustrate how the former can achieve the functionality required by the latter.

A Review of Decision Support Systems in Telecare

This paper presents an overview of the state-of-the-art on decision support systems (DSS) in telecare. The main aspect examined is the use of smaller subsystems—components in an integrated DSS, with emphasis on two application areas: medical home unit monitoring and real-time prioritisation of the alerts generated by them, and drug interaction checking. The paper suggests the development of an integrated hybrid telecare DSS synthesizing most of the technologies reviewed. Implementation issues are also examined, with an emphasis on the international trend towards the development of platform-independent, component-based, distributed software.