Catálogo de publicaciones - libros

Software architects have techniques to deal with many quality attributes such as performance, reliability, and maintainability. Usability, however, has traditionally been concerned primarily with presentation and not been a concern of software architects beyond separating the user interface from the remainder of the application. In this paper, we introduce usability-supporting architectural patterns. Each pattern describes a usability concern that is not supported by separation alone. For each concern, a usability-supporting architectural pattern provides the forces from the characteristics of the task and environment, the human, and the state of the software to motivate an implementation independent solution cast in terms of the responsibilities that must be fulfilled to satisfy the forces. Furthermore, each pattern includes a sample solution implemented in the context of an overriding separation based pattern such as J2EE Model View Controller.

This paper addresses the issue of usability testing in a component-based software engineering environment, specifically measuring the usability of different versions of a component in a more powerful manner than other, more holistic, usability methods. Three component-specific usability measures are presented: an objective performance measure, a perceived ease-of-use measure, and a satisfaction measure. The objective performance measure is derived from the message exchange between components recorded in a log file, whereas the other measures are obtained through a questionnaire. The power of the measures was studied in an experimental setting. Eight different prototypes of a mobile telephone were subjected to usability tests, in which 80 subjects participated. Analyses of the statistical power of these measures show that the component-specific performance measure can be more powerful than overall usability measures, which means fewer users are needed in a test.

Studies of software engineering projects show that a large number of usability related change requests are made after its deployment. Fixing usability problems during the later stages of development often proves to be costly, since many of the necessary changes require changes to the system that cannot be easily accommodated by its software architecture. These high costs prevent developers from meeting all the usability requirements, resulting in systems with less than optimal usability. The successful development of a usable software system therefore must include creating a software architecture that supports the right level of usability. Unfortunately, no documented evidence exists of architecture level assessment techniques focusing on usability. To support software architects in creating a software architecture that supports usability, we present a scenario based assessment technique that has been successfully applied in several cases. Explicit evaluation of usability during architectural design may reduce the risk of building a system that fails to meet its usability requirements and may prevent high costs incurring adaptive maintenance activities once the system has been implemented.

Although model-based approaches focusing on task modeling for user-interface design are well accepted among researchers, they are rarely used by industrial developers. Besides a lack of theoretical frameworks for task modeling insufficient tool support might be the reason for the low diffusion of this approach to interactive software-development processes. Thus, we explored the leading-edge tools TaOSpec, ProcessLens, and CTTE with respect to the formal representation of work tasks, and the creation of task scenarios. The results reveal that current model-based design approaches should be more conceivable by their users with respect to work tasks and their organization. This objective can be met by embedding scenario-based design elements into current tools, thus, increasing integrative tool and organizational development support.

The last few years a lot of research efforts have been spent on user interfaces for pervasive computing. This paper shows a design process and a runtime architecture, DynaMo-AID, that provide design support and a runtime architecture for context-aware user interfaces. In the process attention is focused on the specification of the tasks the user and the application will have to perform, together with other entities related to tasks, like dialog and presentation. In this paper we will show how we can model tasks, dialogs, and presentation when the designer wants to develop context-sensitive user interfaces. Besides the design process, a runtime architecture will be presented supporting context-sensitive user interfaces. Pervasive user interfaces can change during the runtime of the interactive application due to a change of context or when a service becomes available to the application. We will show that traditional models like task, environment and dialog model have to be extended to tackle these new problems. This is why we provide modeling and runtime support solutions for design and development of context-sensitive user interfaces.

Business processes are usually described by abstract workflow specifications. However, existing workflow descriptions are often too restricted to reflect the true nature of work. For instance tasks might be added or deleted during execution. The presently available workflow management systems insufficiently support the desired flexibility for workflows. In this article we present an approach, how certain kinds of adaptability can be achieved on the base of task modelling combined with the principle of ”Order & Supply”. Task models offer means to describe the way humans perform tasks in cooperation focussing on the individual level. We show that the principles of task modelling can also be used for cooperative workflow models providing means on group level.

We report the specification and evaluation of a browser designed to support sharing of digital photographs. The project integrated outcomes from experiments, ethnographic observations, and single-case immersive observations to specify and evaluate browser technologies. As well as providing and evaluating new browser concepts, a key outcome of our research is a case study showing the successful integration of ethnography and experimentation, research and design methods that are often viewed as orthogonal, sometimes even mutually exclusive, in HCI.

Despite the growing numbers and diversity of electronic documents, the ways in which they are cataloged and retrieved remain largely unchanged. Storing a document requires classifying it, usually into a hierarchic file system. Such classification schemes aren’t easy to use, causing undue cognitive loads. The shortcomings of current approaches are mostly felt when retrieving documents. Indeed, how a document was classified often provides the main clue to its whereabouts. However, place is seldom what is most readily remembered by users. We argue that the use of narratives, whereby users ’tell the story’ of a document, not only in terms of previous interactions with the computer but also relating to a wider ”real world” context, will allow for a more natural and efficient retrieval of documents. In support of this, we describe a study where 60 stories about documents were collected and analyzed. The most common narrative elements were identified (time, storage and purpose), and we gained insights on the elements themselves, discovering several probable transitions. From those results, we extract important guidelines for the design of narrative-based document retrieval interfaces. Those guidelines were then validated with the help of two low-fidelity prototypes designed from experimental data. This paper presents these guidelines whilst discussing their relevance to design issues.

In this paper, we argue that current user interface modeling tools are developed using a formalism-centric approach that does not support the needs of modern software development. In order to solve this problem we need both usable and expressive notations and tools that enable the creation of user-interface specifications that leverage the design and thought process. In this paper we present the CanonSketch tool. CanonSketch supports a new UI specification language – Canonical Abstract Prototypes (CAP) – that bridges the gap between envisioned user behavior and the concrete user interface. The tool also supports two additional and synchronized views of the UI: the Wisdom UML presentation extension and concrete HTML user interfaces. In this way the tool seamlessly supports designers while switching from high level abstract views of the UI and low-level concrete realizations.

Most of the current WWW is made up of dynamic pages. The development of dynamic pages is a difficult and costly endeavour, out-of-reach for most users, experts, and content producers. We have developed a set of techniques to support the edition of dynamic web pages in a WYSIWYG environment. In this paper we focus on specific techniques for inferring changes to page generation procedures from users actions on examples of the pages generated by these procedures. More specifically, we propose techniques for detecting iteration patterns in users’ behavior in web page editing tasks involving page structures like lists, tables and other iterative HTML constructs. Such patterns are used in our authoring tool, DESK, where a specialized assistant, DESK-A, detects iteration patterns and generates, using Programming by Example, a programmatic representation of the user’s actions. Iteration patterns help obtain a more detailed characterization of users’ intent, based on user monitoring techniques, that is put in relation to application knowledge automatically extracted by our system from HTML pages. DESK-A relieves end-users from having to learn programming and specification languages for editing dynamic-generated web pages.