Improving Reusability of Hazard Analysis Model with Hazard Template for Deriving Safety Properties of Home Network System

The recent ubiquitous/pervasive technologies allow general household appliances to be connected within the network at home. The home network system (HNS, for short) is comprised of such networked appliances to provide various services and applications for home users. The great advantage of HNS lies in integrating (or orchestrating) features of multiple appliances, which yields more value-added and powerful services. We call such services HNS integrated services. In developing and providing a HNS integrated service, the service provider must guarantee that the service is safe for inhabitants, house properties and their surrounding environment. As for the HNS integrated services, however, we have to consider the safety much more carefully. This paper presents a systematic method that can derive the verifiable safety properties from a given HNS model and hazard contexts. Specifically, we propose the HNS Hazard Analysis Model (HNS-HAM) for deriving safety properties with conducting a goal-oriented analysis. The analysis yields cause-and-effect chains from the abstract hazard contexts to the concrete attributes and operations of HNS objects (appliances, services, and environment). Then the safety properties and their responsible operations are derived from the complete model, which give the strong rationale of the safety of the HNS. On the other hand, to make the proposed method more practical, it is necessary to save the analysis cost while appliances and services in the HNS are added or changed. For this, we have also proposed the notion of the hazard template, which characterizes the generic portion of the HNS-HAM. For every hazard context, the hazard template is supposed to be constructed once by the safety experts. The template can be reused for various kinds of the HNS objects for the common hazard context. The reusable templates make it possible to save the analysis cost and improve the quality of the HNS-HAM.