An ECA-based framework for decentralized coordination of ubiquitous web services

Emerging ubiquitous computing network is expected to consist of a variety of heterogeneous and distributed devices. While web services technology is increasingly being considered as a promising solution to support the inter-operability between such heterogeneous devices via well-defined protocol, currently there is no effective framework reported in the literature that can address the problem of coordinating the web services-enabled devices. This paper considers a ubiquitous computing environment that is comprised of active, autonomous devices interacting with each other through web services, and presents an ECA (Event-Condition-Action)-based framework for effective coordination of those devices. Specifically, we first present an XML-based language for describing ECA rules that are embedded in web service-enabled devices. An ECA rule, when triggered by an internal or external event to the device, can result in the invocation of appropriate web services in the system. Subsequently, we consider the situation in which the rules are introduced and managed by multiple, independent users, and propose effective mechanisms that can detect and resolve potential inconsistencies among the rules. The presented ECA-based coordination approach is expected to facilitate seamless inter-operation among the web service-enabled devices in the emerging ubiquitous computing environments.