Anke Dittmar

Task models as basis for requirements engineering and software execution

In this paper we discuss an approach linking GUI specifications to abstract dialog models. Both specifications are based on task models describing behavioral features. It will be shown how first prototypes of interactive systems, which are generated from user interface models, can help to capture requirements. Users can interactively play with prototypes. Tool support is also provided for co-operative work of different users, which starts with abstract canonical prototypes that can evolve to concrete GUI specifications.

Linking GUI elements to tasks: supporting an evolutionary design process

In this paper we discuss an approach for linking GUI specifications to more abstract dialogue models and supporting an evolutionary design process. These specifications are linked to task models describing behavioural characteristics. First prototypes of interactive systems are interactively generated. The automatically generated XUL specifications are refined using a GUI editor, which allows replacing of user interface elements by other elements or components. Components are predesigned parts of user interfaces, and could optionally be parameterised. This enables us to support GUI design using patterns.For illustration we are going to show a design cycle from task model to abstract user interfaces and finally to a concrete user interface. The design process is supported by patterns.Additionally, a proposal is presented of how to keep connections between concrete user interface (CUI), abstract user interface (AUI) and a task model. These connections can be used to propagate changes in a task model or an AUI only to affected parts of a CUI, instead of recreating the whole CUI after a modification has been done.In this paper we primarily focus on deletion, moving and adding tasks to an AUI and the implication of these procedures to a CUI. More complicated problems like splitting or merging of tasks are not addressed in this paper.The avoiding of unnecessary recreation processes for a CUI can reduce the amount of time and work needed in model-driven software development.

Higher-Order Task Models

Based on a revision of the common task understanding in model-based approaches a formal meta-model is proposed which allows more expressive task descriptions. A task is considered as a meta-action which produces models about situations, goals and actions by applying domain knowledge. The approach unifies procedural and state knowledge. As a consequence, higher-order actions are possible. The suggested approach is an answer to the need for more dynamic task models. It supports specifications of context sensitive and cooperative tasks.

Support for task modeling: a ”constructive” exploration

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.

Getting SW Engineers on Board: Task Modelling with Activity Diagrams

This paper argues for a transfer of knowledge and experience gained in task-based design to Software Engineering. A transformation of task models into activity diagrams as part of UML is proposed. By using familiar notations, software engineers might be encouraged to accept task modelling and to pay more attention to users and their tasks. Generally, different presentations of a model can help to increase its acceptance by various stakeholders. The presented approach allows both the visualization of task models as activity diagrams as well as task modelling with activity diagrams. Corresponding tool support is presented which includes the animation of task models. The tool itself was developed in a model-based way.

The Influence of Improved Task Models on Dialogues

Model-based approaches support a flexible design process and the development of consistent device-dependent applications. However, their full strength can only be achieved by expressive sub-models allowing to capture conceptual knowledge as early as possible. In this paper we demonstrate how improvements to task models, which can be seen as the heart of model-based techniques, help to develop more appropriate models and prototypes of user interfaces (UIs).

More precise descriptions of temporal relations within task models

Task models are more and more accepted as a prerequisite for a good design of interactive systems. In the existing approaches, the description of temporal relations between the subtasks corresponds to the hierarchical decomposition of a task. This paper proposes a separate specification of actions and goals constituting tasks where an action model called simple action model describes the hierarchical and sequential character of the task. An extension of the simple action model by additional temporal constraints is suggested. Thus, a more general models can be specified which can be adapted to actual conditions. The adapted action model allows a more precise modelling of temporal relations between subactions. This approach can contribute to a more flexible task modelling.

Task-based design revisited

This paper investigates the role of task modeling in model-based design. It is shown that task models are mainly used to support a specification-driven design process. Models about current task situations and more specific task descriptions play a marginal role. Task sketching is proposed to complement specification-driven modeling activities. The co-development of representations of current and envisioned practices is encouraged to support a shared design understanding and creativity. A detailed example illustrates basic ideas. Task models are represented in HOPS. Advantages of this specification formalism over conventional task modeling are shown with respect to task sketching. Models can be combined with illustrations, narratives or other design material at different levels of abstraction. Animations of enriched models help to explore the design space.

Personal ecologies of calendar artifacts

The use of calendars for work and personal activities has been widely investigated for decades and the term calendar work, coined by Palen (CHI 17-24,1999), refers to the many ways people employ and interact with calendars. Previous research has focused on calendar usage in specific domains or on the differences between paper and digital calendars. The current paper is positioned somewhat differently by exploring calendars as object in personal ecologies of calendar artifacts. In such personal calendar ecologies, the users, their tasks, their practices, and the calendar artifacts adapt and evolve together. In addition, individual users are typically engaged in various activities in specific contexts (realms) that are established and maintained by groups of people, supporting the overarching culture of these realms. As such, the web of common practices, activities and tasks, as well as the calendar artifacts shape the individual calendar work. To our knowledge, this article is the first study that investigates diverse personal ecologies of calendar artifacts. To this end we collected detailed user data with (a) exploratory interviews and (b) the Day-Reconstruction Method. The results indicate that the changing demands in daily life, the availability of new tools, and the participants’ knowledge about the costs and benefits of their calendar work and about the consequences of potential failures influence their tendency to explore and possibly integrate new calendar artifacts and appear implicated in the deliberate non-use of new technology. It appears that paper and digital calendar artifacts continue to co-exist. The results indicate an existing ‘appointment culture’ with a high demand of precisely scheduled episodes, and the importance of calendar artifacts for maintaining work and personal relationships in the light of the travel and new technologies for communication.

Two-Level Personas for Nested Design Spaces

The persona approach is often treated as a single user-centered design method, but there are variations and adaptations for different design contexts which go beyond local customization. The paper discusses a set of dimensions and success criteria for describing the different persona uses, presenting a new framework. It then specifically investigates personas in the context of end-user development. Professional designers need to consider the design space for potential end-user tools. In addition they need to understand that their users are often designers themselves (they are designer-users), requiring that they also consider the design spaces of their users. Two-level personas are introduced to make professional designers more aware of such nested design spaces. A two-level persona consists of one first-level persona and a set of second-level personas to additionally represent complex designer-user relationships. The effectiveness of the approach is investigated in an exploratory empirical study. The results suggest that two-level personas add value when designing end-user design tools.