Silvia E. Gordillo

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.

Modeling and Composing Navigational Concerns in Web Applications. Requirements and Design Issues.

Complex applications, in particular Web applications, deal with a myriad of different concerns and some of them affect several others. The result is that these crosscutting concerns are scattered throughout different software artifacts and tangled with other concerns. In this paper we present an approach for modeling and composing navigational concerns in Web applications. By showing how to build partial navigation scenarios with user interaction diagrams, analyzing how they crosscut and defining corresponding composition rules, we add modularity to the requirements specification stage, facilitating reasoning about the requirements and a consequent tradeoff analysis to support informed decisions on architectural choices. Moreover, by focusing on navigation concerns during the early stages of applications development, we aim to address the impact of crosscutting concerns in design models, improve the discovering of meaningful design artefacts and improve traceability of design decisions

Generating a catalog of unanticipated schemas in class hierarchies using Formal Concept Analysis

Context: Inheritance is the cornerstone of object-oriented development, supporting conceptual modeling, subtype polymorphism and software reuse. But inheritance can be used in subtle ways that make complex systems hard to understand and extend, due to the presence of implicit dependencies in the inheritance hierarchy. Objective: Although these dependencies often specify well-known schemas (i.e., recurrent design or coding patterns, such as hook and template methods), new unanticipated dependency schemas arise in practice, and can consequently be hard to recognize and detect. Thus, a developer making changes or extensions to an object-oriented system needs to understand these implicit contracts defined by the dependencies between a class and its subclasses, or risk that seemingly innocuous changes break them. Method: To tackle this problem, we have developed an approach based on Formal Concept Analysis. Our Formal Concept Analysis based-Reverse Engineering methodology (FoCARE) identifies undocumented hierarchical dependencies in a hierarchy by taking into account the existing structure and behavior of classes and subclasses. Results: We validate our approach by applying it to a large and non-trivial case study, yielding a catalog of hierarchy schemas, each one composed of a set of dependencies over methods and attributes in a class hierarchy. We show how the discovered dependency schemas can be used not only to identify good design practices, but also to expose bad smells in design, thereby helping developers in initial reengineering phases to develop a first mental model of a system. Although some of the identified schemas are already documented in existing literature, with our approach based on Formal Concept Analysis (FCA), we are also able to identify previously unidentified schemas. Conclusions: FCA is an effective tool because it is an ideal classification mining tool to identify commonalities between software artifacts, and usually these commonalities reveal known and unknown characteristics of the software artifacts. We also show that once a catalog of useful schemas stabilizes after several runs of FoCARE, the added cost of FCA is no longer needed.

Design Patterns for Context-Aware Adaptation

In this paper we show how the judicious use of design patterns can improve the design of context-awareness in software systems. We first review well-known problems in the development of context-aware applications. Next, we present our view on the design process of context-aware software; we introduce design patterns and explain why they can be useful to improve the quality of this kind of applications. We finally present some design patterns we mined by researching on successful context-aware approaches. Some concluding remarks are finally presented together with further work we are pursuing.

Generating the architecture of GIS applications with design patterns

In this paper we show the impact of Design Patterns in the generation of the software architecture underlying a GIS application. We first discuss the problem of adding spatial features to Iegacy object oriented applications, then we present three Design Patterns specific to this domain: Reference System, Roles and Appearances to illustrate our claims. We introduce Design Patterns as a conceptual tool both, to record design experience and to support evolvable design micro-architectures, and describe the previously mentioned patterns, exemplifying their use within the design of GIS applications. Finally, we discuss some further issues in our

Engineering Accessible Web Applications. An Aspect-Oriented Approach

The development of accessible Web software is complicated for several reasons. Though some of them are technological, the majority are related with the need to compose different and, many times, unrelated design concerns which may be functional as in the case of most of the specific application’s requirements, or non-functional such as Accessibility itself. In this paper, we present a novel approach to conceive, design and develop Accessible Web applications in an aspect-oriented manner. In order to reach our goal, we provide some modeling techniques that we specifically developed for handling the non-functional, generic and crosscutting characteristics of the Accessibility concerns. Specifically, we have enriched User Interaction Diagrams with integration points, which are used to reason and document Accessibility for activity modeling during user interface design. Then by instantiating a Softgoal Interdependency Graph template with association tables, we work on an abstract interface model (composed by ontology widgets) to obtain a concrete and accessible interface model for the Web application being developed. We use a real application example to illustrate our ideas and point out the advantages of a clear separation of concerns throughout the development life-cycle.

Refining an object-oriented GIS design model: topologies and field data

In this paper we present an architecture to manipulate object topologies and field-oriented data. We first show how to extend the object oriented model presented in [5] by defining an extended location micro-arquitecture; next we explain how we use extended locations to define a set of structures and operations to manipulate different kinds of vector based topologies such as Node and ArcNode topologies. We then present the object-oriented architecture for dealing with field data; we show how this architecture alIows us to decouple data belonging to a continuous field from corresponding samples, their implementations and the estimation methods used to calculate points in the corresponding field. We finally discuss present some further work on implementing this architecture.

Separation of structural concerns in physical hypermedia models

In this paper we propose a modeling and design approach for building physical hypermedia applications, i.e. those mobile applications in which physical and digital objects are related and explored using the hypermedia paradigm. We show that by separating the geographical and domain concerns we gain in modularity, and evolution ease. We first review the state of the art of this kind of software systems, arguing about the need of a systematic modeling approach; we next present a light extension to the OOHDM design approach, incorporating physical objects and ”walkable” links; next we generalize our approach and show how to improve concern separation and integration in hypermedia design models. We compare our approach with others in the field of physical and ubiquitous hypermedia and in the more generic software engineering field. Some concluding remarks and further work are finally presented.

Developing GIS Applications with Objects: A Design Patterns Approach

In this paper we present an object-oriented approach for designing GIS applications; it combines well known software engineering practices with the use of design patterns as a conceptual tool to cope with recurrent problems appearing in the GIS domain. Our approach allows the designer to decouple the conceptual definition of application objects from their spatial representation. In this way, GIS applications can evolve smoothly, because maintenance is achieved by focusing on different concerns at different times. We show that our approach is also useful to support spatial features in conventional applications built with object-oriented technology. The structure of this paper is as follows: We first introduce design patterns, an efficient strategy to record design experience; then we discuss the most common design problems a developer of GIS applications must face. The core of our method is then presented by explaining how the use of decorators helps in extending objects to incorporate spatial attributes and behavior. Next, we analyze some recurrent design problems in the GIS domain and present some new patterns addressing those problems. Some further work is finally discussed.

Supporting users tasks with personal information management and web forms augmentation

Currently, many tasks performed on the Web prompt users to provide personal information through forms. Despite the fact that most users are familiarized with this kind of interaction technique, the use of Web forms is not always straightforward. Indeed, some users might need assistance to understand labels and complex data format required to fill in form fields that, quite often, vary from a Web site to another even when requesting similar data. Filling in forms can be tedious and repetitive as many Web sites request similar information. In this work we analyze users interactions with Web forms and propose an approach for enhancing Web forms using client-side adaptation techniques in order to assist users to fill in Web forms. As the use of Web forms is closely related to the management of personal information our approach includes the support for data exchange between users personal information management systems (PIMs) and third-party Web forms. The approach is illustrated by a set of client-side adaptation tools and a pervasive Personal Information Management Systems called PIMI.