org.apache.flink.streaming.kafka.test.base

Class RollingAdditionMapper

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.api.common.functions.RichMapFunction<KafkaEvent,KafkaEvent>

org.apache.flink.streaming.kafka.test.base.RollingAdditionMapper

All Implemented Interfaces:

Serializable, Function, MapFunction<KafkaEvent,KafkaEvent>, RichFunction

public class RollingAdditionMapper
extends RichMapFunction<KafkaEvent,KafkaEvent>

A RichMapFunction that continuously outputs the current total frequency count of a key. The current total count is keyed state managed by Flink.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RollingAdditionMapper()

Method Summary

Modifier and Type	Method and Description
KafkaEvent	map(KafkaEvent event) The mapping method.
void	open(Configuration parameters) Initialization method for the function.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RollingAdditionMapper

public RollingAdditionMapper()

Method Detail

map

public KafkaEvent map(KafkaEvent event)
               throws Exception

Description copied from interface: MapFunction

The mapping method. Takes an element from the input data set and transforms it into exactly one element.

Specified by:

map in interface MapFunction<KafkaEvent,KafkaEvent>

Specified by:

map in class RichMapFunction<KafkaEvent,KafkaEvent>

Parameters:

event - The input value.

Returns:

The transformed value

Throws:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.

open

public void open(Configuration parameters)
          throws Exception

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyMapper extends FilterFunction<String> {

     private String searchString;

     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }

     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractRichFunction

Parameters:

parameters - The configuration containing the parameters attached to the contract.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

See Also:

Configuration