Automating Feature Requests for User-Driven Model Evolution at Runtime

As software projects progress, requirements can change and diverge between individual users. This happens in particular in consumer software. Subsequently, the maintenance of such software becomes a complex and resource-intensive task. However, system parts can be modified and individualized at runtime if domain-specific evolution and configuration tasks are transferred to the user. This reduces development efforts and contributes to sustainable and long-living software products called eternal software. In model-driven engineering, a target for this evolution is the domain's metamodel. The adaptive object model architecture style is a known approach, enabling variable metamodels at runtime. However, specifying transformations for evolving the metamodel can be challenging, particularly for end-users. Editor-based solutions are complex to develop and require multiple user interactions to achieve a desired change. We propose a new approach based on textual feature requests from community-driven software development to address this issue. We define a language for feature requests that target model evolution. We define this language on top of formal delta models. End-users can use the language to formulate model evolution on a high level. These requests are transformed into a sequence of low-level change operations, which are executed at runtime. A case study shows the approach's feasibility. We realize an issue tracker where users can evolve domain classes using textual requests at runtime. A user study evaluates usability.