Jacqueline Floch

Using architecture models for runtime adaptability

Every software system has architecture. The architecture strongly influences the software systems properties, including maintainability and runtime properties such as performance and reliability. By describing the architecture in models, we can make the architecture explicit. Developers typically use software architecture models at design time to capture the significant decisions about a software systems organization and to describe and establish a common understanding about the systems abstract properties. In the MADAM (mobility- and adaptation-enabling middleware) project, we aim to facilitate adaptive application development for mobile computing. We follow an architecture-centric approach where we represent architecture models at runtime to allow generic middleware components to reason about and control adaptation.

Using product line techniques to build adaptive systems

Adaptive systems are able to adapt their properties and resource requirements at runtime in response to dynamically varying user needs and resource constraints. With the emergence of mobile and service oriented computing, such variation is becoming increasingly common, and the need for adaptivity is increasing accordingly. Software product line engineering has proved itself as an efficient way to deal with varying user needs and resource constraints. In this paper we present an approach to building adaptive systems based on product line oriented techniques such as variability modeling and component based architectures. By representing the product line architecture at runtime, we are able to delegate much of the complexity of adaptation to a reusable adaptation platform. To validate our approach we have built a prototype adaptation platform and developed a few pilot applications exploiting the platform to achieve adaptivity.

Composing components and services using a planning-based adaptation middleware

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.

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

Model-based user interface adaptation

Most work on model-based cross-platform user interface development is based on an assumption that the user interfaces on the different platforms should be as similar as possible. Much work on mobile user interfaces claim the opposite A¢â‚¬â€œ that user interfaces on a mobile platform should have features not applicable on a stationary one and vise versa. Exploiting contextual information in user interfaces on mobile equipment is a prime example of this. This paper focus on this dichotomy between common development and exploiting platform specific features (or having specialized versions) on each platform. Few or none of the existing model-based languages and tools for user interface development are able to combine these two needs. These aspects are initially very difficult to combine, but in the paper we present an approach that makes this possible. First we briefly present our modelling approach, we pinpoint some of the general differences between mobile and stationary user interfaces, and we present an approach to building such self adapting systems where the adaptation is handled by generic middleware. Our approach builds on component frameworks and variability engineering to achieve adaptable systems, and property modelling, architectural reflection and context monitoring to support dynamic self-adaptation. With this as a background we investigate how the presented modelling approach may be extended and combined with the adaptive architecture to facilitate mode l-based user interface adaptation. Finally, we present some more general principles for how model-based approaches may be used when developing adaptive user interfaces.

ICT convergence: modeling issues

Even though ICT convergence is a well-established and a-dopted concept, there is no consensus about the underlying software engineering approach to convergent ICT systems. Telecom engineers and software engineers traditionally use different approaches when developing services and applications. A main question is whether or not the differences are justified and should be maintained in the context of convergence? In this paper, we seek to answer this question by analyzing the different nature of the telecom domain and the computing domain. We identify a few fundamental differences that must be bridged when making convergent systems and we investigate how UML can be used as an enabler to build such bridges.

Supporting evolution and maintenance by using a flexible automatic code generator

Generating code automatically from the design level increases product quality and productivity but also facilitates maintenance and evolution by limiting changes to the design level. Flexibility is a basic requirement that should be fulfilled by automatic code generators: the translation strategies should be easily adapted to different platforms or company standards and also to the evolution of the system which they produce. We present our approach to flexible code generation, in the frame of our SDL methodology, and the code generator tool ProgGen. The methodology focuses on the design phase and distinguishes between functional design (i.e. describing behavior) and implementation design (i.e. describing the concrete system). The implementation design description plays a central role in the code generation process. ProgGen is a generic tool which can be used to produce SDL translators; the output is controlled by a set of code skeletons. The skeletons can easily be tailored to support changes in the hand-coded software interfaces (e.g. driver interfaces), in the implementation platform or in the non functional requirements. The use of ProgGen at Alcatel Telecom Norway illustrates how the code generation process has been formalized. Finally, we show how ProgGen is used in the ESPRIT project PROTEUS where our goal is to complete automation of the entire system building.

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.

A middleware centric approach to building self-adapting systems

The use of handheld networked devices to access information systems by people moving around is spreading rapidly. Systems being used in this way typically face dynamic variation in their operating environment. This poses new challenges for system developers that need to build systems that adapt dynamically to the changing operating environment in order to maintain usability and usefulness for mobile users. In this paper we propose an approach to building such self-adapting systems where the adaptation is handled by generic middleware. Our approach builds on component frameworks and variability engineering to achieve adaptable systems, and property modelling, architectural reflection and context monitoring to support dynamic self-adaptation.

Self-adaptation for everyday systems

The use of handheld networked devices to access information systems by people moving around is spreading rapidly. Systems being used in this way typically face dynamic variation in their operating environment. In order to maintain the usability and usefulness for mobile users, self-adapting systems are needed. Self-adaptation has so far typically been applied only to mission critical systems at considerable additional cost. However, we now need ways to implement such capabilities that are affordable also in everyday systems development.In this paper we propose an approach to building such self-adapting systems where the adaptation is handled by generic middleware. The proposed approach builds on component frameworks and variability engineering to achieve adaptable systems, and property modelling, architectural reflection and context monitoring to support dynamic self-adaptation. We define a set of requirements for affordable self-adaptation and discuss the proposed approach in relation to these requirements.