The reusability of modular, embeddable components is a key determinant for the success of modern programming languages to ensure efficient and high-quality development. However, there is a gap in the field of domain-specific modeling regarding reusable components at the model level. While libraries are relatively common and a de facto standard for prominent programming languages, establishing model libraries is still in its infancy. This paper specifies building a model-driven component library that utilizes a self-extension mechanism. We demonstrate an approach to structure, build, and integrate such a library using a wide range of GUI components, from essential atomic elements and more complex composed components to specifically tailored ones for particular application domains. Employing such libraries at the model level further supports the goal of model-driven engineering to assist domain experts in efficiently building high-quality systems.

When applying model-driven engineering in an agile environment, new requirements continuously expand the domain scope and trigger an extension of the concepts covered by the Domain-Specific Language (DSL). While programming languages streamline code extension and reuse through libraries, similar approaches for DSLs are more complex or target a specific language. We present and discuss an approach for designing DSLs with a self-extension mechanism to enable model library creation and seamless reuse. We use the self-extension mechanism to introduce concepts in models, gather reusable models into a library, and provide an infrastructure for its usage. We explain our language-specific realization of the self-extension mechanism using a DSL and discuss model libraries of the DSL with a use case from practice. The approach provides more flexibility for agile model-driven engineering. It enables application modelers to introduce and reuse concepts via models without changing the DSL, reducing the communication overhead within the development team.