A CONTEXT MODEL WITH A TIME-DEPENDENT MULTI-LAYER EXCEPTION HANDLING POLICY

Abstract. Context aware ubiquitous technology provides us with much more conve-niences in our everyday life by dening contextual information in appropriate ways. Up to now, there has been a vast amount of researches and many context models proposed. Many characteristics have been incorporated into such models such as users, physical locations, available resources, etc. Some also take time factors into consideration. Most still focus on the interactions between context and users/groups rather than discussing follow-up operations deeply. In this study, we extend the scope of the context model to include metadata related to services and use it to describe the behaviours of general op-erations. Also, by further dividing the time factor into levels of importance, we can use time as the primary control factor to manipulate some specic operations so that oper-ations could be triggered by real time constraints and handled properly. Some critical operations within the whole system may need to be handled by specic users or groups. The occurrence of unexpected situations when the default operator cannot proceed with the corresponding operation on time must be taken care of by a pre-designed time-dependent multi-layer exception handling policy to maintain the integrity and security of the system. We also propose a critical operation scenario, describe the processes of our model and explain the importance of time driven events to prove its applicability