Specifying Evolving Requirements Models with TimedURN

Abstract

The User Requirements Notation (URN) supports the elicitation, specification, and analysis of integrated goal and scenario models. The analysis of the goal and scenario models focuses on one snapshot in time and does not allow the model to change over time. While several models may be created that represent different stages of a system, managing several, slightly different model copies is a space-consuming, time-consuming, and error-prone task that makes it difficult to maintain consistency across the model copies. This paper introduces TimedURN, an extension of the URN standard, which enables the modeling and analysis of a comprehensive set of changes to a goal and scenario model over time. The changes to the model are captured in one base model, which eases system evolution. The metamodel for TimedURN is presented and it is argued that it can also be applied to other modeling languages. Furthermore, the usefulness of TimedURN is illustrated with an example from the sustainability domain and the comprehensiveness of the supported types of changes is assessed.