Teleo-Reactive policies for managing human-centric pervasive services

Event-Condition-Action (ECA) policies are often used to manage various aspects of adaptation and execution of pervasive systems. Such policies are well suited for services where: 1) given actions are reliably executed when they are requested, 2) there is no priority ordering amongst multiple available actions, and 3) execution is instantaneous with respect to the validity of conditions under which they were initiated. However, for a pervasive service that integrates human agents and human activities, these assumptions do not generally hold. Humans may misbehave by postponing the execution of certain actions or ignoring them all together. Performing an action may take a long time so that the action is no longer needed or more important actions may need to be executed. Managing such behaviours through ECA policies is complex and difficult to implement. This paper introduces a new management policy type, called a Teleo-Reactive policy, whose semantics are based on continuous monitoring of the environment and prioritising available actions. The semantics result in more flexible and concise formulation of management policies for human-centric pervasive services. We demonstrate how these policies can be applied in a real-world use case scenario set in a nursing home and describe the underlying implementation based on the Android's Java platform.