In early-phase requirements engineering, modeling stakeholder goals and intentions helps stakeholders understand the problem context and evaluate tradeoffs, by exploring possible “what if” questions. Prior research allows modelers to make evaluation assignments to desired goals and generate possible selections for task and dependency alternatives, but this treats models as static snapshots, where the evaluation of the fulfillment of an intention remains constant once it has been determined. Using these techniques, stakeholders are unable to reason about possible evolutions, leaving questions about project viability unanswered when the fulfillment of goals or availability of components is not guaranteed in the future. In this article, we formalize the Evolving Intentions framework for specifying, modeling, and reasoning about goals that change over time. Using the Tropos language, we specify a set of functions that define how intentions and relationships evolve, and use path-based analysis for asking a variety of “what if” questions about such changes. We illustrate the framework using the Bike Lanes example and prove correctness of the analysis. Finally, we demonstrate scalability and effectiveness, enabling stakeholders to explore model evolution.

在早期需求工程中，对利益相关者的目标和意图进行建模可以通过探索可能的“假设”问题来帮助利益相关者理解问题背景并评估权衡取舍。先前的研究允许建模人员对期望的目标进行评估分配，并为任务和依存关系备选方案生成可能的选择，但这将模型视为静态快照，一旦确定了意图，对实现的评估就保持不变。使用这些技术，利益相关者无法推理可能的发展，而当将来无法保证实现目标或组件的可用性时，就无法回答有关项目可行性的问题。在本文中，我们对“不断发展的意图”框架进行了形式化，以用于指定，建模，以及随着时间推移而变化的目标的推理。使用Tropos语言，我们指定了一组函数，这些函数定义意图和关系的演变方式，并使用基于路径的分析来询问有关此类变化的各种“假设”问题。我们使用Bike Lanes示例说明该框架，并证明分析的正确性。最后，我们展示了可伸缩性和有效性，使利益相关者能够探索模型的演变。