In this chapter we've learned about Drools stream mode for CEP. Events in Drools are immutable objects with strong time-related relationships. CEP has great value, especially if we need to make complex decisions over a high number of events. The engine automatically detects when an event is no longer needed and makes sure that it can be garbage collected. We've seen the use of time/length sliding windows and temporal operators.
This chapter also discussed the Drools type declarations, which can define metadata on top of existing types or define new types. As was demonstrated, new types are useful for rule decomposition.
Various examples of rules from a fictive fraud detection system were presented.
Drools is a very extensible tool. The development ...