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The demand for increased software quality has resulted in quality being more of differentiator between products than it ever has been before. For this reason, software developers need objective and valid measures for use in the evaluation and improvement of product quality from the initial stages of development. Class diagrams are a key artifact in the development of object-oriented (OO) software because they lay the foundation for all later design and implementation work. It follows that emphasizing class diagram quality may significantly contribute to higher quality OO software systems. The primary aim of this work, therefore, is to present a survey, as complete as possible, of the existing relevant works regarding class diagram metrics. Thus, from works previously published, researchers and practitioners alike may gain broad and ready access to insights for measuring these quality characteristics. Another aim of this work is to help reveal areas of research either lacking completion or yet to undertaken. A SURVEY OF METRICS FOR UML CLASS DIAGRAMS 60 J OURNAL OF OBJECT TECHNOLOGY V OL. 4, NO. 9 Recently, paradigms such as Model-Driven Development [Atkin03] and the Model-Driven Architecture [OMG02] have emphasized the importance of "good" models from the beginning of the life cycle. For that reason, the main focus must be on the quality of models obtained in these "early" stages. In the OO paradigm one of the key artifacts is the class diagram. The class diagram constitutes the backbone of the OO development and provides a solid foundation for the design and the implementation of software. Therefore, class diagram quality has great influence over the system that is ultimately implemented. Quality in software products is characterised by the presence of different external attributes 1 such as functionality, reliability, usability, efficiency, maintainability and portability [ISO01]. But these attributes can only be measured late in the OO software development life cycle. Therefore, it is necessary to find early indicators of such qualities based, for example, on the structural properties of class diagrams [Briand00a]. This is the context where software measurement is fundamental, because measures can allow us to evaluate class diagram quality characteristics in an objective way, thus avoiding a bias in the evaluation process. Measuring class diagram quality allows OO software designers: • to identify weak design spots when it costs less to improve them, rather than repair consequent errors at later implementation phases. • to choose between design alternatives in an objective way. • to predict external quality characteristics such as, maintainability, reusability, etc., and improve resource allocation based on these predictions. Although in the OO software measurement arena the need for measures that can be applied in the early phases of the development process is emerging, up until a few years ago the work done in this sense was scarce because most software measurement researchers focused on the measurement of c...

The goal of any modeling activity is a complete and accurate understanding of the real-world domain, within the bounds of the problem at hand and keeping in mind the goals of the stakeholders involved. High-quality representations are critical to that understanding. This paper proposes a comprehensive Conceptual Modeling Quality Framework, bringing together two well-known quality frameworks: the framework of Lindland, Sindre, and Sølvberg (LSS) and that of Wand and Weber based on Bunge's ontology (BWW). This framework builds upon the strengths of the LSS and BWW frameworks, bringing together and organizing the various quality cornerstones and then defining the many quality dimensions that connect one to another. It presents a unified view of conceptual modeling quality that can benefit both researchers and practitioners.

Context: Programming courses are compulsory for most engineering degrees, but students’ performance on these courses is often not as good as expected. Programming is difficult for students to learn, given that it includes a lot of new, complex, and abstract topics. All of this has led experts to the conclusion that new teaching techniques are required if students are to be motivated and engaged in learning on programming courses. Gamification has come to be an effective technique in education in general, and is especially useful in programming courses. This motivated us to develop an open source gamified platform, called UDPiler, for use in a programming course. Objective: The main goal of this article is to obtain empirical evidence on the improvement of students’ learning performance when using UDPiler in comparison to a non-gamified compiler. Method: A quasi-experiment was performed with two groups of first-year engineering students at Diego Portales University in Chile, using a non-gamified compiler and a gamified platform, respectively. Results: The results reveal that the students obtained better marks when the gamified platform was used to learn C programming. In addition, there is statistical significance in favor of there being a positive effect on the learning performance of those students who used the gamified platform. Conclusions: The results allow us to conclude that gamification is an encouraging approach with which to teach C programming, a finding that is aligned with previous empirical studies concerning gamification on programming courses, carried out in academic contexts. Nonetheless, we are aware that further validation is also required to corroborate and strengthen the findings obtained and to investigate whether the kind of gamified elements (mechanics, dynamics, and aesthetics) used have any influence on students’ performance, among other issues that deserve further investigation and that are explained throughout this article.

We carried out a family of experiments to investigate whether the use of UML models produced in the requirements analysis process helps in the comprehensibility and modifiability of source code. The family consists of a controlled experiment and 3 external replications carried out with students and professionals from Italy and Spain. 86 participants with different abilities and levels of experience with UML took part. The results of the experiments were integrated through the use of meta-analysis. The results of both the individual experiments and meta-analysis indicate that UML models produced in the requirements analysis process influence neither the comprehensibility of source code nor its modifiability.

The main goal of this work is to present a family of empirical studies that we have carried out to investigate whether the use of composite states may improve the understandability of UML statechart diagrams derived from class diagrams. Our hypotheses derive from conventional wisdom, which says that hierarchical modeling mechanisms are helpful in mastering the complexity of a software system. In our research, we have carried out three empirical studies, consisting of five experiments in total. The studies differed somewhat as regards the size of the UML statechart models, though their size and the complexity of the models were chosen so that they could be analyzed by the subjects within a limited time period. The studies also differed with respect to the type of subjects (students vs. professionals), the familiarity of the subjects with the domains of the diagrams, and other factors. To integrate the results obtained from each of the five experiments, we performed a meta-analysis study which allowed us to take into account the differences between studies and to obtain the overall effect that the use of composite states has on the understandability of UML statechart diagrams throughout all the experiments. The results Empir Software Eng (2009) obtained are not completely conclusive. They cast doubts on the usefulness of composite states for a better understanding and memorizing of UML statechart diagrams. Composite states seem only to be helpful for acquiring knowledge from the diagrams. At any rate, it should be noted that these results are affected by the previous experience of the subjects on modeling, as well as by the size and complexity of the UML statechart diagrams we used, so care should be taken when generalizing our results.

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The usefulness of measures for the analysis and design of object oriented (OO) software is increasingly being recognized in the field of software engineering research. In particular, recognition of the need for early indicators of external quality attributes is increasing. We investigate through experimentation whether a collection of UML class diagram measures could be good predictors of two main subcharacteristics of the maintainability of class diagrams: understandability and modifiability. Results obtained from a controlled experiment and a replica support the idea that useful prediction models for class diagrams understandability and modifiability can be built on the basis of early measures, in particular, measures that capture structural complexity through associations and generalizations. Moreover, these measures seem to be correlated with the subjective perception of the subjects about the complexity of the diagrams. This fact shows, to some extent, that the objective measures capture the same aspects as the subjective ones. However, despite our encouraging findings, further empirical studies, especially using data Empir Software Eng (taken from real projects performed in industrial settings, are needed. Such further study will yield a comprehensive body of knowledge and experience about building prediction models for understandability and modifiability.