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12.8. Stream Mode
Stream mode processes events chronologically as they are inserted into the rules engine. Stream mode uses a session clock that enables the rules engine to process events as they occur in time. The session clock enables processing events as they occur based on the age of the events. Stream mode also synchronizes streams of events (so events in different streams can be processed in chronological order), implements sliding windows of interest, and enables automatic life-cycle management.
The requirements for using stream mode are the following:
- Events in each stream must be ordered chronologically.
- A session clock must be present to synchronize event streams.
Note
The application does not need to enforce ordering events between streams, but the use of event streams that have not been synchronized may cause unexpected results.
Stream mode can be enabled by setting a system property, using configuration property files, or via the API.
The API call follows:
KieBaseConfiguration config = KieServices.Factory.get().newKieBaseConfiguration(); config.setOption( EventProcessingOption.STREAM );
The equivalent property follows:
drools.eventProcessingMode = stream
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