Specifying and enforcing high-level semantic obligation policies

Obligation policies specify management actions that must be performed when a particular kind of event occurs and certain conditions are satisfied. Large scale distributed systems often produce event streams containing large volumes of low-level events. In many cases, these streams also contain multimedia data (consisting of text, audio or video). Hence, a key challenge is to allow policy writers to specify obligation policies based on high-level events, that may be derived after performing appropriate processing on raw, low-level events. In this paper, we propose a semantic obligation policy specification language called Eagle, which is based on patterns of high-level events, represented as RDF graph patterns. Our policy enforcement architecture uses a compiler that builds a workflow for producing a stream of events, which match the high-level event pattern specified in a policy. This workflow consists of a number of event sources and event processing components, which are described semantically. We present the policy language and enforcement architecture in this paper. (C) 2008 Elsevier B. V. All rights reserved.