Context: Attack-Defense Trees (ADTs) are a graphical notation used to model and evaluate security requirements. ADTs are popular because they facilitate communication among different stakeholders involved in system security evaluation and are formal enough to be verified using methods like model checking. The understandability and user-friendliness of ADTs are claimed as key factors in their success, but these aspects, along with user acceptance, have not been evaluated empirically. Objectives: This paper presents an experiment with 25 subjects designed to assess the understandability and user acceptance of the ADT notation, along with an internal replication involving 49 subjects. Methods: The experiments adapt the Method Evaluation Model (MEM) to examine understandability variables (i.e., effectiveness and efficiency in using ADTs) and user acceptance variables (i.e., ease of use, usefulness, and intention to use). The MEM is also used to evaluate the relationships between these dimensions. In addition, a comparative analysis of the results of the two experiments is carried out. Results: With some minor differences, the outcomes of the two experiments are aligned. The results demonstrate that ADTs are well understood by participants, with values of understandability variables significantly above established thresholds. They are also highly appreciated, particularly for their ease of use. The results also show that users who are more effective in using the notation tend to evaluate it better in terms of usefulness. Conclusion: These studies provide empirical evidence supporting both the understandability and perceived acceptance of ADTs, thus encouraging further adoption of the notation in industrial contexts, and development of supporting tools.

Language workbenches are tools that enable the definition, reuse and composition of programming languages and their ecosystem. This breed of frameworks aims to make the development of new languages easier and more affordable. Consequently, the comprehensibility of the language used in a language workbench (i.e., the meta-language) should be an important aspect to consider and evaluate. To the best of our knowledge, although the quantitative aspects of language workbenches are often discussed in the literature, the evaluation of comprehensibility is typically neglected.Neverlang is a language workbench that enables the definition of languages with a modular approach. This paper presents a preliminary study that intends to assess the comprehensibility of Neverlang programs, evaluated in terms of users’ effectiveness and efficiency in a code comprehension task. The study also investigates the relationship between Neverlang comprehensibility and the users’ working memory capacity. Furthermore, we intend to capture the relationship between Neverlang comprehensibility and users’ acceptance, in terms of perceived ease of use, perceived usefulness, and intention to use. Our preliminary results on 10 subjects suggest that the users’ working memory capacity may be related to the ability to comprehend Neverlang programs. On the other hand, effectiveness and efficiency do not appear to be associated with an increase in users’ acceptance variables.

DataMod 2020 aims to bring together practitioners and researchers from academia, industry and research institutions interested in the combined application of computational modelling methods with data-driven techniques from the areas of knowledge management, data mining and machine learning. Modelling methodologies of interest include automata, agents, Petri nets, process algebras and rewriting systems. Application domains include social systems, ecology, biology, medicine, smart cities, governance, security, education, software engineering, and any other field that deals with complex systems and large amounts of data. Papers can present research results in any of the themes of interest for the symposium as well as application experiences, tools and promising preliminary ideas. Papers dealing with synergistic approaches that integrate modelling and knowledge management/discovery or that exploit knowledge management/discovery to develop/syntesise system models are especially welcome.

Automatic support for web accessibility validation needs to evolve for several reasons. The increasingly recognised importance of accessibility implies that various stakeholders, with different expertise, look at it from different viewpoints and have different requirements regarding the types of outputs they expect. The technologies used to support Web application access are evolving along with the associated accessibility guidelines. We present a novel tool that aims to provide flexible and open support for addressing such issues. We describe the design of its main features, including support for recent guidelines and tailored results presentations, and report on first technical and empirical validations that have provided positive feedback.