As you have learned so far, one of the main components of Oracle Event Processing is the CQL processor. The CQL processor is the brain of the EPN. In the CQL processor, you will code rules that determine the processing of the events. Common examples are rules that perform filtering of the events, or that aggregate input events into summary output events. The following diagram shows a CQL processor in an EPN:
The CQL processor is programmed using a language called Continuous Query Language (CQL). This may sound a bit odd, but the rationale for the name will become apparent later on when we understand the proper semantics of CQL.
CQL is an extension to SQL, the common language of databases. These extensions, as you shall see in the next sections, deal with additional logic for handling time and events that are not part of the standard SQL.
Without further ado, let's immerge into the interesting world of CQL, which many may find to be a paradigm shift in the way they think about...