Feature models are a helpful means to document, manage, maintain, and configure the variability of a software system, and thus are a core artifact in software product-line engineering. Due to the various purposes of feature models, they can be a cross-cutting concern in an organization, integrating technical and business aspects. For this reason, various stakeholders (e.g., developers and consultants) may get involved into modeling the features of a software product line. Currently, collaboration in such a scenario can only be done with face-to-face meetings or by combining single-user feature-model editors with additional communication and version-control systems. While face-to-face meetings are often costly and impractical, using version-control systems can cause merge conflicts and inconsistency within a model, due to the different intentions of the involved stakeholders. Advanced tools that solve these problems by enabling collaborative, real-time feature modeling, analogous to Google Docs or Overleaf for text editing, are missing. In this article, we build on a previous paper and describe (1) the extended formal foundations of collaborative, real-time feature modeling, (2) our conflict resolution algorithm in more detail, (3) proofs that our formalization converges and preserves causality as well as user intentions, (4) the implementation of our prototype, and (5) the results of an empirical evaluation to assess the prototype’s usability. Our contributions provide the basis for advancing existing feature-modeling tools and practices to support collaborative feature modeling. The results of our evaluation show that our prototype is considered helpful and valuable by 17 users, also indicating potential for extending our tool and opportunities for new research directions.

特征模型是记录，管理，维护和配置软件系统可变性的有用方法，因此是软件产品线工程中的核心工件。由于功能模型的各种目的，它们可能是组织中集成技术和业务方面的跨部门关注点。因此，各种利益相关者（例如，开发人员和顾问）可能会参与到对软件产品线的功能进行建模的过程中。当前，在这种情况下的协作只能通过面对面会议或将单用户功能模型编辑器与其他通信和版本控制系统结合使用来完成。虽然面对面的会议通常成本高昂且不切实际，但是使用版本控制系统可能会导致模型中的合并冲突和不一致，由于相关利益相关者的不同意图。缺少通过启用协作的实时功能建模来解决这些问题的高级工具，类似于Google Docs或Overleaf进行文本编辑。在本文的基础上，我们描述了（1）协作实时特征建模的扩展形式基础，（2）我们的冲突解决算法更详细，（3）证明了我们的形式能收敛并保留因果关系以及用户的意图，（4）我们的原型的实现，以及（5）评估原型可用性的实证评估结果。我们的贡献为推进现有要素建模工具和实践提供了基础，以支持协作要素建模。