Structuring and Composition Mechanisms to Address Scalability Issues in Task Models

Abstract

Abstract. Along tasks analysis and modeling history it has been demonstrated by experience that task modeling activities become cumbersome when performed on large, real-life systems. However, one of the main goals of task models is to provide designers with a structured and complete description of the users tasks especially when these user tasks are numerous and/or complex. Several authors proposed to handle that problem by providing tools aiming at supporting both construction and understanding (usually via simulation) of models. One of the most popular examples is CTTE environment which is dedicated to the engineering of CTT task models. The paper shows how to extend notations for task description with two kinds of mechanisms: composition and refinement/abstraction. Refinement/abstraction mechanisms make it possible to decompose a task model into several models and to interconnect them. Composition mechanisms make it possible to define communication means between task models. The paper proposes a precise definition of these mechanisms, their integration into a notation for describing task models and demonstrates that altogether, these two structuring mechanisms support the effective exploitation of task models for large scale application. The use of the mechanisms is presented on a real-life case study from the space domain describing operators' tasks to monitor a satellite and manage failures.

Identification of UX dimensions for incident reporting systems with mobile applications in urban contexts: a longitudinal study

“…Moreover, modelbased task analysis provided an accurate description of user tasks. As described in Martinie et al (2011), task models do not only improve the understanding of user tasks, but they also can be used to assess if an incident reporting system was effectively implemented to support the specified set of user tasks.…”

“…In order to represent such temporal and operational constraints, we have built a task model using the HAMSTERS notation (which stands for Human-centered Assessment and Modeling to Support Task Engineering for Resilient Systems) as illustrated in Fig. 2 (see (Martinie et al 2011) further details about the HAMSTER notation). By simulating the task model, we can extract many different scenarios which can be compared with observation of user tasks with empirical methods.…”

Managing Complexity in Activity Specifications by Separation of Concerns and Reusability

“…The term "pattern" was used, but it referred only to a sub-tree. This kind of reuse is called submodel in the HAMSTERS environment ( [2], [3]). In [9] the usage of generic task patterns was suggested.…”

“…They have been proven to be useful as specification languages of functional requirements in Human Computer Interaction (HCI) (e.g., [1], [2], [3], and [4]). Additionally, they were used to support smart environments [5] and workflow management systems [6].…”

Tasks Model Composition: Beyond Data, Representing User Activities

“…However, when applied to real-life systems, tasks notations end up in very large, hard-to-manage models thus making task modeling a time-consuming and sometimes painful activity. In [3] we have investigated structuring mechanisms for task models including encapsulation of task, reuse and task patterns. The lessons we learned is that without the proper structuring mechanism, developers can be easily overwhelmed by their models and lose the focus on the end-users, thus creating ineffective compositions.…”