Usability Aspects of Ensuring Temporal Integrity Constraints: A Critical Appraisal

Usability and user interfaces are key properties of Busi-ness-to-Consumer (B2C) systems. This paper analyzes Web-based reservation systems, a widely used class of B2C systems. A main element of a reservation is temporal data about its start and end. Therefore, a key issue for us-ability of reservation systems is a suitable treatment of temporal data and of the associated integrity constraints.We classify temporal integrity constraints into single and relational ones, differentiating the latter between binary and ternary relationships. In a broad analysis of Web-based reservation systems we found that many systems fail in adhering intuitively to obvious integrity constraints, deliver unexpected results, or provide misleading error messages.The widely differing implementations of comparatively simple constraints cast a bad light on the current state of website development. Our results indicate that the theory of system development, with its recommendations of developing and (re)using patterns and services, has not in-fluenced practical Web system development to a suffi-cient degree. We also sketch further research projects that systematize the options of handling temporal data to pro-vide a basis for temporal usability studies, the develop-ment of a maturity model for handling temporal data, and the systematic evaluation of today’s reservation systems.