Institute of Electrical & Electronic Engineers
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. The authors present a distributed query platform that tackles these problems. Their 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. They evaluate several aspects of their prototype in a Cloud computing environment.