Brian Babcock Shivnath Babu Mayur Datar Rajeev Motwani Dilys Thomas Operator scheduling in data stream systems. 333-353 2004 13 VLDB J. 4 http://dx.doi.org/10.1007/s00778-004-0132-6 db/journals/vldb/vldb13.html#BabcockBDMT04