Nearchos Paspallis

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.

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.

Playing MUSIC — building context‐aware and self‐adaptive mobile applications

Although the idea of context‐awareness was introduced almost two decades ago, few mobile software applications are available today that can sense and adapt to their run‐time environment. The development of context‐aware and self‐adaptive applications is complex and few developers have experience in this area. On the basis of several demonstrators built by the joint European research project MUSIC, this paper describes typical context and adaptation features relevant for the development of context‐aware and self‐adaptive mobile applications. We explain how the demonstrators were realised using the open‐source platform MUSIC and present the feedback of the developers of these demonstrators. The main contribution of this paper is to show how the development complexity of context‐aware and self‐adaptive mobile applications can be mastered by using an adaptation framework such as MUSIC. Copyright

An Approach for Developing Adaptive, Mobile Applications with Separation of Concerns

Modern mobile computing paradigms have set new challenges for the development of distributed mobile applications and services. Because of the variability which characterizes the context of such environments, it is important that mobile applications are developed so that they can dynamically adapt their extra-functional behavior, in order to optimize the experience perceived by their users. This paper proposes an approach for developing adaptive, mobile applications. It is argued that this approach eases the development effort by clearly separating the work required for the development of the application logic from that required for enabling its adaptive behavior. It is argued that in addition to mitigating the development complexity, this approach also enables a new generation of distributed applications. The novelty in the latter is that the applications can dynamically and collaboratively adapt in an ad-hoc manner to improve the quality of the services offered to mobile users

Distributed context management in a mobility and adaptation enabling middleware (MADAM)

As computing devices are getting smaller, we tend to bring them everywhere. Consequently the operating conditions of the devices are constantly changing (e.g. changing user requirements, change in the system context and environment context). In order to be usable and dependable, applications and services need to self-adapt to changes in context. This work describes a context management approach for reducing the complexity of context aggregation and utilisation. The context manager is a core component in the MADAM (Mobility and ADaptation enAbling Middleware) project.

Putting Context in Context: The Role and Design of Context Management in a Mobility and Adaptation Enabling Middleware

The operating context of mobile applications and services is constantly changing. In order to achieve higher levels of usability, mobile applications and services need to adapt to changes in context. This paper argues the need for adaptation enabling middleware that simplifies the development of context aware adaptive applications, and makes it economically and practically feasible to develop such applications. We claim that the traditional approach of simply providing contextual information to applications and let them handle the adaptation can be ineffective. We suggest a holistic approach where context management is an integral part of a more comprehensive adaptation enabling middleware. This paper describes the role and the design of the context management component in such a middleware architecture. The feasibility of the approach is demonstrated in a scenario where proof-of-concept implementations have been developed and evaluated.