Patent attributes
A complex event processor is described which has a communications interface configured to retrieve event data by pulling it from one or more sources and to receive at least one live event stream pushed to the interface. An event processing pipeline connected to the communications interface comprises a plurality of operator nodes connected between the communications interface and a combiner node which is a node configured to combine event data from the source and from the live event stream. The communications interface is configured to retrieve events from the source and to push the events retrieved from the source along the event processing pipeline towards the combiner node. The communications interface is configured to retrieve and push the retrieved events only in response to request messages passed in an upstream direction from the combiner node to the communications interface along the pipeline.