This work originated at Standford and is described in the paper The CQL Continuous Query Language: Semantic Foundations and Query Execution
The code has been downloaded from the Standford's web-site, the project has been closed in 2006.
I am going to try to resurrect it, first by creating some test harness, then by modernising the C++, and learning the code along the way. Then, perhaps, I will have some ideas about where to take it further.