Distributed continuous queries over Web service event streams

Complex Event Processing over Web service event streams poses huge challenges with regard to efficient, scalable execution as well as expressive models and languages that account for the dynamics in long-running queries. We present a distributed query platform that tackles these problems. Our novel query model permits to specify inputs that provide data for other inputs and need to be processed first. An XQuery language extension lets users easily express such dependencies, which are then continuously resolved with the required data at runtime. Query specifications are abstracted from physical deployment, allowing the platform to distribute the execution and to elastically scale up and down. We evaluate several aspects of our prototype in a Cloud computing environment.