Language usage analysis for EMF metamodels on GitHub

Summary

Context EMF metamodels lie at the heart of model-based approaches for a variety of tasks, notably for defining the abstract syntax of modeling languages. The language design of EMF metamodels itself is part of a design process, where the needs of its specific range of users should be satisfied. Studying how people actually use the language in the wild would enable empirical feedback for improving the design of the EMF metamodeling language.
Objective Our goal is to study the language usage of EMF metamodels in public engineered projects on GitHub. We aim to reveal information about the usage of specific language constructs, whether they match the language design. Based on our findings, we plan to suggest improvements in the EMF metamodelling language.
Method We adopt a sample study research strategy and collect data from the EMF metamodels on GitHub. After a series of preprocessing steps including filtering out non-engineered projects and deduplication, we employ an analytics workflow on top of a graph database to formulate generalizing statements about the artifacts under study. Based on the results, we also give actionable suggestions for the EMF metamodeling language design.
Results We have conducted various analyses on metaclass, attribute, feature/relationship usage as well as specific parts of the language: annotations and generics. Our findings reveal that the most used metaclasses are not the main building blocks of the language, but rather auxiliary ones. Some of the metaclasses, metaclass features and relations are almost never used. There are a few attributes which are almost exclusively used with a single value or
illegal values. Some of the language features such as special forms of generics are very rarely used. Based on our findings, we provide suggestions to improve the EMF language, e.g. removing a language element, restricting its values or refining the metaclass hierarchy.
Conclusions In this paper, we present an extensive empirical study into the language usage of EMF metamodels on GitHub. We believe this study fills a gap in the literature of model analytics and will hopefully help future improvement of the EMF metamodeling language.