Enhancing Flexibility in User Interaction Modeling by Adding Design Uncertainty to IFML

User interaction (UI) design is an important task in the development of software applications: in fact the success of the application itself, as well as the business behind it, is strongly related to the user experience. Unfortunately, designers can obtain realistic feedback from users about their actual expectations only at runtime, by analyzing the user behavior over the final application. A possible solution to this problem is to integrate the user feedback in the design phase, for example through A/B split testing, which allows to test the effectiveness of different variants of the application interface. However, so far A/B testing has been addressed only through manual coding and a-posteriori refactoring based on the analysis of the results. Model-driven development may enable the integration of such techniques with runtime log analysis and design-time application specifications. Unfortunately, creating new alternatives in the model usually corresponds to a combinatorial explosion of the application versions, making the testing hard to manage. In this paper, we propose a model-driven approach that enables to denote design alternatives in a compact way by adopting a model for uncertainty, integrated with a model for the user interaction design. Thus, the multiple possibilities can be represented by a single user interaction model (i.e., IFML model) from which a single software application will be generated, including all the variations that need to be evaluated. Uncertainty can then be solved by integrating the results of user behavior analysis (for instance, over the application logs of a web site). Thanks to this, our approach considerably reduces the costs of the user interaction optimization.