http://www.infoq.com/news/2009/06/drools-5.0-release
http://www.javacodegeeks.com/2014/03/event-processing-in-camel-drools.html
http://www.opennms.org/wiki/Drools_Correlation_Engine
http://www.openxtra.co.uk/blog/top-5-open-source-event-correlation-tools/
http://www.opennms.org/wiki/Log_Correlator
http://www.ibm.com/developerworks/cn/java/j-drools5/
http://docs.jboss.org/drools/release/5.3.0.Final/drools-expert-docs/html_single/#d0e1898
https://developer.jboss.org/wiki/EventSequencing