ContinuousQueryLanguage (CQL) is an SQL based language for maintaining continuous queries over long periods. Such queries are suitable for real-time and reactive programs - those where keeping an up-to-date view and latency are important (such as collaborative editing, traffic or safety or security monitoring, command and control, robotics). The original CQL was developed at Stanford between 2002-2006 as part of a project named 'STREAM'; that implementation is now available under the BSD license. In 2007, OracleCorporation introduced 'Oracle ContinuousQueryLanguage', also abbreviated CQL, as part of its ComplexEventProcessing (CEP) framework and application server. This language varies from Stanford's but serves a similar role and purpose.

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See also:
* http://infolab.stanford.edu/stream/
* StructuredQueryLanguage
* ComplexEventProcessing
* EventStreamProcessing
* ReactiveProgramming
* PublishSubscribeModel
* DataDistributionService
* KayLanguage (and KDB)