org.apache.flink.streaming.api.functions.co.CoFlatMapFunction Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.flink.streaming.api.functions.co;
import org.apache.flink.annotation.Public;
import org.apache.flink.api.common.functions.Function;
import org.apache.flink.util.Collector;
import java.io.Serializable;
/**
* A CoFlatMapFunction implements a flat-map transformation over two connected streams.
*
* The same instance of the transformation function is used to transform both of the connected
* streams. That way, the stream transformations can share state.
*
*
An example for the use of connected streams would be to apply rules that change over time onto
* elements of a stream. One of the connected streams has the rules, the other stream the elements
* to apply the rules to. The operation on the connected stream maintains the current set of rules
* in the state. It may receive either a rule update (from the first stream) and update the state,
* or a data element (from the second stream) and apply the rules in the state to the element. The
* result of applying the rules would be emitted.
*
* @param Type of the first input.
* @param Type of the second input.
* @param Output type.
*/
@Public
public interface CoFlatMapFunction extends Function, Serializable {
/**
* This method is called for each element in the first of the connected streams.
*
* @param value The stream element
* @param out The collector to emit resulting elements to
* @throws Exception The function may throw exceptions which cause the streaming program to fail
* and go into recovery.
*/
void flatMap1(IN1 value, Collector out) throws Exception;
/**
* This method is called for each element in the second of the connected streams.
*
* @param value The stream element
* @param out The collector to emit resulting elements to
* @throws Exception The function may throw exceptions which cause the streaming program to fail
* and go into recovery.
*/
void flatMap2(IN2 value, Collector out) throws Exception;
}