| Billions of dollars are lost annually due to software errors and many of these errors can be traced back to unclear or unspecified software requirements. One major challenge in specifying requirements is understanding the problem space, which can rarely be achieved without collaboration among various types of stakeholders such as domain experts, end users, managers, and developers, etc. Poor stakeholder collaboration in requirements engineering could have disastrous consequences as misunderstandings and conflicts can propagate from the requirements into the final product.;Stakeholders collaborate in an iterative process of overlapping activities that includes eliciting requirements, specifying the requirements (iterative drafts of the specification), analyzing and validating the requirements (including analyzing and validating existing and proposed business processes), and negotiating the requirements. Collaboration among different stakeholders is complex for a variety of reasons including language and expertise barriers as well as tension between different stakeholders' goals, needs, and interests in a software system. We believe that the choice of RE specification technique plays a key role in establishing mutual understanding among stakeholders because it serves as the artifact used to specify elicited requirements and validate them as well as the source and target of negotiation. More specifically, we hypothesize that a RE approach that provides both precision and usability is key for collaborative RE, i.e., establishing mutual understanding among stakeholders by enabling and contributing to better understanding, communication, and manipulation of requirements.;Narrative requirements, such as use cases and scenarios, are often used in requirements engineering because different kinds of stakeholders can relate to them. Previous work has also explored relationships among narrative requirements and property-based requirements such as goals and non-functional requirements and successfully derived goal models from scenarios. Narrative requirements can serve as an effective foundation for collaborative requirements activities as well as for other types of requirements specification. Precision is achieved by restricting the expression of narrative requirements to a defined language and usability is provided by a tool that alleviates some of the burdens of a precise language through visualization and interaction mechanisms. We implement and explore these solutions in Preusa, a semi-formal language for expressing narrative requirements and iMuse -- Integrated Model-based Use-case and Storytelling Environment, an environment to be used by different types of stakeholders for visual construction, modification, and interactive exploration of requirements expressed in Preusa. The contributions of this work include: (1) We address one of the unresolved and essential problems in RE -- stakeholder collaboration -- through a specification technique that provides precision and usability. (2) We make several advances in terms of a RE language and a tool to express, edit, and view narrative requirements. (3) We have validated the approach using several groups of technical and nontechnical stakeholders including professional Software Developers and Physicians. (4) We have gained several interesting insights regarding tradeoffs and other design decisions with respect to precision and usability of the language and visualization and interaction mechanisms. (5) We have gained several interesting and novel perspectives on collaborative requirements engineering, particularly with respect to requirements creation and understanding. |
