Adding a Textual Syntax to an Existing Graphical Modeling Language: Experience Report with GRL

A modelling language usually has an abstract syntax (e.g., expressed with a metamodel) separate from its concrete syntax. The question explored in this paper is: how easy is it to add a textual concrete syntax to an existing language that offers only a concrete graphical syntax? To answer this question, this paper reports on lessons learned during the creation of a textual syntax (supported by an editor and transformation tool) for the Goal-oriented Requirement Language (GRL), which is part of the User Requirements Notation standard. Our experiment shows that although current technologies help create textual modelling languages efficiently with feature-rich editors, there are important conflicts between the reuse of existing metamodels and the usability of the resulting textual syntax that require attention.