Andres Fortier

Dealing with variability in context-aware mobile software

Mobile context-aware software pose a set of challenging requirements to developers as these applications exhibit novel features, such as handling varied sensing devices and dynamically adapting to the users context (e.g. his or her location), and evolve quickly according to technological advances. In this paper, we discuss how to handle variability both across different domains and during the evolution of a single application. We present a set of design structures for solving different problems related with mobility (such as location sensing, behaviour adaptation, etc.), together with the design rationale underlying them, and show how these sound micro-architectural constructs impact on variability. Our presentation is illustrated with case studies in different domains.

Seamless Personalization of E-commerce Applications

In this paper we present an original approach for personalizing complex Web applications, in particular e-commerce applications. This approach is based on a clear separation of concerns, namely: base application functionality, user profile management, and personalization rules, and supports seamless addition of personalization features (such as recommendations, special offers, individual interfaces, etc). We first explain our view of e-commerce applications as views on application models, and briefly explain why personalization functionality should be dealt by separating concerns. We next introduce a simple example and focus on different personalization patterns, emphasizing on behavior personalization. We show which design structures are the most appropriated for obtaining seamless extensions to existing software. We finally discuss some further aspects in building customized e-commerce software.

A Modular Architecture for Context Sensing

Due to the technological evolution, context-aware computing is slowly moving from dream to reality. These applications heavily rely in sensing the users environment and abstracting this information to perform high-level adaptation. While technological issues have been mostly addressed, sensing software is usually built in a handcrafted way, which turns into building ad-hoc solutions for every new application. To solve this problem, we consider that context sensing should be regarded as a software engineering problem and not a simple implementation issue. In this paper we present a software architecture for dealing with context-sensing aspects in a high-level modular way. We show that by using this approach, evolution issues typical of mobile wireless software can be managed easily by replacing or composing software modules without compromising performance.

Seamless engineering of location-aware services

In this paper we present a novel approach to design and implement applications that provide location-aware services. We show how a clear separation of design concerns (e.g. applicative, context-specific, etc) helps to improve modularity. We stress that by using dependency mechanism among outstanding components we can get rid of explicit rule-based approach thus simplifying evolution and maintenance. We first discuss some related work in this field. Next, we introduce a simple exemplary scenario and present the big picture of our architectural approach. Then we detail the process of service definition and activation. A discussion on communication and composition mechanisms is next presented and we end presenting some concluding remarks and further work.

A Flexible Architecture for Context-Aware Physical Hypermedia

In this paper we present the rationale and the main components for a modular and extensible architecture for building and deploying physical hypermedia software. We show that this kind of software systems poses strong requirements on supporting software (such as Web browsers) because they involve complex context-aware navigation semantics. By using some simple archetypical examples we also show how to provide context-aware assistance to the mobile user, as he explores the physical world.

Decoupling Design Concerns in Location-Aware Services

In this paper we present an original approach to design and implement applications that provide location-aware services. Our approach emphasizes a clear separation of the relevant concerns in the application (base behavior, context-sensitive properties, services, etc.) to improve modularity and thus simplify evo-lurion. We first motivate the problem with a simple scenario of a virtual campus; we next discuss which are the most important concerns in the application, we explain why we must separate them and show a simple approach to achieve this separation. We analyze the most important (sub) models in which we decompose a location-aware application and explain the use of dependency mechanisms to trigger behaviors related with the provision of services according to the user position. We briefly describe a proof of concept by means of an archetypical implementation we developed following our ideas. We next compare our work with others and discuss some further work we are pursuing.

Browsing semantics in context-aware mobile hypermedia

Mobile hypermedia applications combine the well-known advantages of the navigational paradigm of the Web with the capabilities of location-aware software. However, there are some subtleties to integrate them synergistically. In this paper we analyze different aspects related with navigation semantics in mobile hypermedia; in particular we discuss the problems which arise in the use of the familiar backward and forward operations when physical navigation in the real world is involved. Using a motivating example, we present a simple model to handle physical and digital navigation in a cohesive way. We also describe a modular implementation of our ideas in an architecture which support context-aware services.

An object-oriented approach for context-aware applications

In this paper we present a novel, object-oriented approach for designing and building applications that provide context-aware services. Our approach emphasizes a clear separation of the relevant concerns in the application (base behavior, context-sensitive properties, services, sensing technologies, etc.) to improve modularity and thus simplify evolution. We first motivate the problem with a simple scenario of a virtual campus; we next present a new context model, which emphasizes on behavior instead of data. We next show the main components of our architecture and a simple approach to achieve a clear separation of concerns. We analyze the most important (sub) models in which we decompose a context-aware application and explain the use of dependency mechanisms to achieve loosely coupled relationships between objects. We also show how to take advantage of a reflective environment like Smalltalk to adapt the applications behavior dynamically and to provide transparent object distribution. We finally compare our work with others and discuss some further work we are pursuing.

Exploiting personal web servers for mobile context-aware applications

There is an increasing trend in moving desktop applications to web browsers, even when the web server is running on the same desktop machine. In this paper, we go further in this direction and show how to combine a web server, a web application framework (enhanced to support desktop-like Model–View–Controller interaction) and a context-aware architecture to develop web-based mobile context-aware applications. By using this approach we take advantage of the well-established web paradigm to design the graphical user interfaces (GUIs) and the inherent ability of the web to mash up applications with external components (such as Google Maps). On top of that, since the web server runs on the device itself, the application can access local resources (such as disk space or sensing devices, which are indispensable for context-aware systems) avoiding the sandbox model of the web browsers. To illustrate our approach we show how a mobile hypermedia system has been built on top of our platform.

Rethinking Context Models

Since the first context-aware applications were designed, context modelling has played a central role. During the last decade many different approaches were proposed to model context, ranging from ad-hoc models to extensions to relational databases or ontologies. In this paper we propose to take a step back and analyse those approaches using the seminal views presented by Paul Dourish in his work (What we talk about when we talk about context). Based on that analysis we propose a set of guidelines that any context model should follow.