Considering impacts and requirements for better understanding of environment interactions in home network services
A home network system (HNS) coordinates various networked home appliances to achieve value-added services. If multiple services are executed at the same time, functional conflicts between the home appliances may occur. These are known as feature interactions (FIs) in the HNS. We have previously defined two kinds of FIs: appliance interactions and environment interactions. Environment interaction refers to an indirect conflict of different appliances in the home environment, which is generally more difficult to capture than appliance interaction. Due to a lack of an amount of environmental impacts and requirements to be satisfied, the previous definition missed some obvious environment interactions, or mis-detected many acceptable cases. In this paper we try to extend the previous formalization by introducing two new concepts. First we propose an environment impact model, which strictly defines how each appliance operation contributes to the environment properties. Second, we introduce an environment requirement to define the expected environment state achieved by each service. We then re-formalize the environment interaction by a condition such that the accumulated impacts violate the requirement of either of the services. A case study with five practical services successfully detects the interactions that could not be characterized by the previous definition.