John Keeney Dominik Roblek Dominic Jones David Lewis Declan O'Sullivan Extending Siena to support more expressive and flexible subscriptions. 35-46 2008 DEBS http://doi.acm.org/10.1145/1385989.1385995 conf/debs/2008 db/conf/debs/debs2008.html#KeeneyRJLO08