Previously, we've discussed how rules should attempt to be atomic and work together to achieve management of complex scenarios. This is very well aligned with CEP as each different rule can deal with one aspect of the aggregation, composition, or abstraction of other events. They can work together to achieve real-time resolution of very complex event situations. We will still need a few added features of Drools to be able to do so, as follows:
How to instruct Drools that an object is to be treated as an event
How to compare two events in time
In the next subsections, we will see how to achieve this using the DRL syntax.
Before we get into the detail about how to define an event, we need to understand a few characteristics of the events. The first characteristic marks a difference between two main types of events—punctual and interval events—as shown in the following:
Punctual events: They are the events that occurred at a specific instance in time...