Language Evolution in Practice: The History of GMF

In consequence of changing requirements and technological progress, software languages are subject to change. The changes affect the language's specification, which in turn affects language processors as well as existing language utterances. Unfortunately, little is known about how software languages evolve in practice. This paper presents a case study on the evolution of four modeling languages provided by the Graphical Modeling Framework. It investigates the following research questions: (1) What is the impact of language changes on related software artifacts?: (2) What activities are performed to implement language changes'? and (3) What kinds of adaptations capture the language changes? We found out that the language changes affect various kinds of related artifacts; the distribution of the activities performed to evolve the languages mirrors the classical software maintenance activities, and most language changes can be captured by a small suite of operators that can also be used to migrate the language utterances.