HORIZON: a Classification and Comparison Framework for Pricing-driven Feature Toggling

Software as a Service (SaaS) has seen rapid growth in recent years, thanks to its ability to adapt to diverse user needs through subscription-based models. However, as pricing models enhance the customization of subscriptions, managing the associated constraints within a system's codebase becomes increasingly challenging. In response, Pricing-driven Development and Operation has emerged to integrate pricing considerations across the software lifecycle. Among its most challenging objectives is regulating feature access according to users' subscriptions -- a process that requires managing a multitude of conditions throughout the system's codebase. Feature toggles have traditionally been employed to manage dynamic system behavior, but their application to pricing-driven constraints presents unique challenges. When used to enforce subscription-based restrictions, toggles must adapt -- among other factors -- to individual user's use of features, ensuring that subscription limits are not exceeded. Despite the increasing significance of this problem, current industrial solutions lack explicit support for pricing-driven feature toggling, and existing academic contributions remain constrained to specific architectures. This paper contributes to fill this gap by introducing HORIZON, a classification and comparison framework for feature toggling tools tailored to pricing-driven environments. Its utility is demonstrated by categorizing the solutions identified in the literature as promising for such environments, revealing both their strengths and limitations, and thereby pinpointing critical avenues for improvement. In doing so, HORIZON not only provides a comprehensive view of the current landscape but also lays the groundwork for a focused research agenda, guiding the development of more robust and adaptable solutions for streamlining SaaS development and operations driven by pricings.