My talk is about CEP (Complex Event Processing: processing for event data as stream) on Fluentd and some ruby/jruby code, and also is about what features and power CEP and Fluentd provides to us. Processing of large amount of data, like access logs, application logs and sensor data becomes now more and more important, but almost all of CEP products are proprietary and too expensive. We doesn't have open source tools and frameworks as simple/powerful as we want. So we are developing open source CEP tool with Fluentd, that have great features for event data collection and delivery. I want to tell you implementation details and practical usages.