When user modeling intersects software engineering: the info-bead user modeling approach

User models (UMs) allow systems to provide personalized services to their users. Nowadays, UMs are developed ad-hoc, as part of specific applications, thus requiring repetitive development efforts. In this paper, we propose the info-bead user modeling approach, which is based on ideas taken from software engineering in general and component-based software development in particular. The basic standalone unit, the info-bead, represents a single user attribute within time-tagged information-items. An info-bead encapsulates an inference process that uses data received from sensors or other info-beads and yields an information-item value. Having standard interfaces, info-beads can be linked, thus creating info-pendants. Both info-beads and info-pendants can be assembled as needed into complex and abstract user models (UMs) and group models (GMs). The goal of the suggested approach is to ease the modeling process and to allow reuse of info beads developed for one UM in other UMs that need the same information. In order to assess the reusability and collaboration capabilities of the info-bead user modeling approach, we developed a prototype tool that enables UM designers, who are not necessarily software developers, to easily select and integrate info-beads for constructing UMs and GMs. We further demonstrated the use of the approach in a museum environment, for modeling of assistive technology ontology and for user modeling in various specific domains. Finally, we analyzed and assessed the characteristics of the approach with respect to existing generic user modeling criteria.