Data warehouse loading and refreshment is typically performed by means of complex software processes called extraction–transformation–loading (ETL). In this paper, we propose a system based on a suite of visual languages for mastering several aspects of the ETL development process, turning it into a visual programming task. The approach can be easily generalized and applied to other data integration contexts beyond data warehouses. It introduces two new visual languages that are used to specify the ETL process, which can also be represented by means of UML activity diagrams. In particular, the first visual language supports data manipulation activities, whereas the second one provides traceability information of attributes to highlight the impact of potential transformations on integrated schemas depending on them. Once the whole ETL process has been visually specified, the designer might invoke the automatic generation of an activity diagram representing a possible orchestration of it based on its dependencies. The designer can edit such a diagram to modify the proposed orchestration provided that changes do not alter data dependencies. The final specification can be translated into code that is executable on the data sources. Finally, the effectiveness of the proposed approach has been validated through a user study in which we have compared the effort needed to design an ETL process in our approach with respect to the one required with main visual approaches described in the literature.Copyright © 2013 John Wiley & Sons, Ltd.

We present an approach and a system to let tutors monitor several important aspects related to online tests, such as learner behavior and test quality. The approach includes the logging of important data related to learner interaction with the system during the execution of online tests and exploits data visualization to highlight information useful to let tutors review and improve the whole assessment process. We have focused on the discovery of behavioral patterns of learners and conceptual relationships among test items. Furthermore, we have led several experiments in our faculty in order to assess the whole approach. In particular, by analyzing the data visualization charts, we have detected several previously unknown test strategies used by the learners. Last, we have detected several correlations among questions, which gave us useful feedbacks on the test quality.