kafka-streams-internals-ProcessorGraphNode.adoc

ProcessorGraphNode

ProcessorGraphNode is a graph node for stateless operators in KStreamImpl and KTableImpl.

When requested to writeToTopology, ProcessorGraphNode simply requests the given InternalTopologyBuilder to add a processor (with the name and the ProcessorSupplier as defined by the given ProcessorParameters).

ProcessorGraphNode is created when:

• KStreamImpl is requested to filter, filterNot, internalSelectKey (for selectKey and groupBy operators), map, mapValues, print, flatMap, flatMapValues, branch, merge, foreach, peek

• KTableImpl is requested to toStream and groupBy

• KStreamImplJoin is requested to join (when KStreamImpl is requested to doJoin for join, outerJoin and leftJoin join operators)

ProcessorGraphNode takes the following to be created:

• Node name

• ProcessorParameters<K, V>

• repartitionRequired flag (default: false)

writeToTopology Method

void writeToTopology(final InternalTopologyBuilder topologyBuilder)

Note	writeToTopology is part of the StreamsGraphNode Contract to…​FIXME.

writeToTopology requests the given InternalTopologyBuilder to add a processor with the name and the ProcessorSupplier as defined by the given ProcessorParameters.