Increasing Expressiveness of Composite Events Using Parameter Contexts

  • Authors:

  • Indrakshi Ray;Wei Huang

  • Affiliations:

  • Department of Computer Science, Colorado State University, Fort Collins, CO 80528-1873;Department of Computer Science, Colorado State University, Fort Collins, CO 80528-1873

  • Venue:
  • ADBIS '08 Proceedings of the 12th East European conference on Advances in Databases and Information Systems
  • Year:
  • 2008

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Abstract

The event-condition-action paradigm (also known as triggersor ECA rules) gives a database "active" capabilities --- the ability to react automatically to changes in the database or the environment. Events can be primitive or composite. Primitive events cannot be decomposed. Different types of primitive events can be composed using event composition operators to form composite events. When a composite event occurs, it is possible that many instances of some constituent primitive event occurs. The contextdetermines which of these primitive events should be considered for evaluating the composite event. Researchers have identified four different contexts, namely, recent, chronicle, continuous, and cumulativethat can be associated with a composite event. Associating a single context with a complex composite event is often times not adequate. Many real-world scenarios cannot be expressed if a composite event is associated with a single context. To solve this problem, we need to associate different contexts for the various constituent primitive events. We show how this can be done by providing a formal semantics for associating contexts with primitive events. Finally, we give algorithms for event detection that implement these semantics.