Safety-Oriented Programming Model Pervasive Computing Systems are Intimate The failure and unreliability can result in strong feeling of betrayal and frustration Intelligent Environment Affects Numerous Aspects of the Daily Life Ensure Safety of the System by Ensuring Safety of All Entities and the Environment as a Whole Safety Enforcement is accomplished by the collaboration at both implementation/ compilation time as well as runtime.

3500°F !! Conflicting DirectivesInvalid Op. Parameters No Emergency HandlingNot Abide by User’s Wishes

Proposed New Model Safety Vs. Expressiveness

Interrupt & Exception Handling Memory access violation Y = X/0 Divided by 0 Interrupt Fire Alarm Impermissible Context Out of Op Range Exception

The Four Elements Device Service User Space

Safety Measure for Device Automatically appended exception handling routine Device Safety: Avoid conflicting directives and unsafe/unacceptable operations, similar to Electric Breaker Regulate the incoming commands and detect abnormal command/access pattern Using maximum and minimum values to filter or red-flag abnormal values

Active Active Contexts Modeling of Services Terminated Aligned Binded User Preference Service Behavior 1 Service Behavior 2 Service Behavior n …. Service Binded Service Registry Services Programmed Services Devices Active Context Change Event Service/Device Change Event User Preference Change Event Impermissible Context Event

Safety Measure for User User Safety 1: Smart space should monitor users’ status and activate emergency measure should users appear to be in danger [using the mechanism for Space Safety] User Safety 2: Smart space should function to serve users’ preference and obey users’ order [using the mechanism for service safety]

Safety Measure for Space Hot Indoor Warm Indoor Cold Indoor Overcooked Steak Cooked Steak Raw Steak Murky air Clean air Context Potential Transitions Preferred Context Impermissible Context Blown fuse Medium power draw Low power draw