org.apache.flink.streaming.connectors.kafka

Class FlinkKafkaConsumer09<T>

java.lang.Object

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

org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction<T>

org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer09<T>

All Implemented Interfaces:

Serializable, org.apache.flink.api.common.functions.Function, org.apache.flink.api.common.functions.RichFunction, org.apache.flink.api.java.typeutils.ResultTypeQueryable<T>, org.apache.flink.runtime.state.CheckpointListener, org.apache.flink.streaming.api.checkpoint.CheckpointedFunction, org.apache.flink.streaming.api.functions.source.ParallelSourceFunction<T>, org.apache.flink.streaming.api.functions.source.SourceFunction<T>

@PublicEvolving
public class FlinkKafkaConsumer09<T>
extends org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

The Flink Kafka Consumer is a streaming data source that pulls a parallel data stream from Apache Kafka 0.9.x. The consumer can run in multiple parallel instances, each of which will pull data from one or more Kafka partitions.

The Flink Kafka Consumer participates in checkpointing and guarantees that no data is lost during a failure, and that the computation processes elements "exactly once". (Note: These guarantees naturally assume that Kafka itself does not loose any data.)

Please note that Flink snapshots the offsets internally as part of its distributed checkpoints. The offsets committed to Kafka / ZooKeeper are only to bring the outside view of progress in sync with Flink's view of the progress. That way, monitoring and other jobs can get a view of how far the Flink Kafka consumer has consumed a topic.

Please refer to Kafka's documentation for the available configuration properties: http://kafka.apache.org/documentation.html#newconsumerconfigs

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.streaming.api.functions.source.SourceFunction

org.apache.flink.streaming.api.functions.source.SourceFunction.SourceContext<T>

Field Summary

Fields

Modifier and Type	Field and Description
static long	DEFAULT_POLL_TIMEOUT From Kafka's Javadoc: The time, in milliseconds, spent waiting in poll if data is not available.
static String	KEY_POLL_TIMEOUT Configuration key to change the polling timeout.
protected long	pollTimeout From Kafka's Javadoc: The time, in milliseconds, spent waiting in poll if data is not available.
protected Properties	properties User-supplied properties for Kafka.

Fields inherited from class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase

deserializer, KEY_DISABLE_METRICS, KEY_PARTITION_DISCOVERY_INTERVAL_MILLIS, MAX_NUM_PENDING_CHECKPOINTS, PARTITION_DISCOVERY_DISABLED

Constructor Summary

Constructors

Constructor and Description
FlinkKafkaConsumer09(List<String> topics, org.apache.flink.api.common.serialization.DeserializationSchema<T> deserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x
FlinkKafkaConsumer09(List<String> topics, org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x
FlinkKafkaConsumer09(Pattern subscriptionPattern, org.apache.flink.api.common.serialization.DeserializationSchema<T> valueDeserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x.
FlinkKafkaConsumer09(Pattern subscriptionPattern, org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x.
FlinkKafkaConsumer09(String topic, org.apache.flink.api.common.serialization.DeserializationSchema<T> valueDeserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x .
FlinkKafkaConsumer09(String topic, org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer, Properties props) Creates a new Kafka streaming source consumer for Kafka 0.9.x

Method Summary

Modifier and Type	Method and Description
protected org.apache.flink.streaming.connectors.kafka.internals.AbstractFetcher<T,?>	createFetcher(org.apache.flink.streaming.api.functions.source.SourceFunction.SourceContext<T> sourceContext, Map<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition,Long> assignedPartitionsWithInitialOffsets, org.apache.flink.util.SerializedValue<org.apache.flink.streaming.api.functions.AssignerWithPeriodicWatermarks<T>> watermarksPeriodic, org.apache.flink.util.SerializedValue<org.apache.flink.streaming.api.functions.AssignerWithPunctuatedWatermarks<T>> watermarksPunctuated, org.apache.flink.streaming.api.operators.StreamingRuntimeContext runtimeContext, org.apache.flink.streaming.connectors.kafka.config.OffsetCommitMode offsetCommitMode, org.apache.flink.metrics.MetricGroup consumerMetricGroup, boolean useMetrics)
protected org.apache.flink.streaming.connectors.kafka.internals.AbstractPartitionDiscoverer	createPartitionDiscoverer(org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicsDescriptor topicsDescriptor, int indexOfThisSubtask, int numParallelSubtasks)
protected Map<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition,Long>	fetchOffsetsWithTimestamp(Collection<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition> partitions, long timestamp)
protected boolean	getIsAutoCommitEnabled()
org.apache.flink.api.common.io.ratelimiting.FlinkConnectorRateLimiter	getRateLimiter()
void	setRateLimiter(org.apache.flink.api.common.io.ratelimiting.FlinkConnectorRateLimiter kafkaRateLimiter) Set a rate limiter to ratelimit bytes read from Kafka.

Methods inherited from class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase

assignTimestampsAndWatermarks, assignTimestampsAndWatermarks, cancel, close, disableFilterRestoredPartitionsWithSubscribedTopics, getProducedType, initializeState, notifyCheckpointComplete, open, run, setCommitOffsetsOnCheckpoints, setStartFromEarliest, setStartFromGroupOffsets, setStartFromLatest, setStartFromSpecificOffsets, setStartFromTimestamp, snapshotState

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

getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Field Detail

KEY_POLL_TIMEOUT

public static final String KEY_POLL_TIMEOUT

Configuration key to change the polling timeout.

See Also:

Constant Field Values

DEFAULT_POLL_TIMEOUT

public static final long DEFAULT_POLL_TIMEOUT

From Kafka's Javadoc: The time, in milliseconds, spent waiting in poll if data is not available. If 0, returns immediately with any records that are available now.

See Also:

Constant Field Values

properties

protected final Properties properties

User-supplied properties for Kafka.

pollTimeout

protected final long pollTimeout

From Kafka's Javadoc: The time, in milliseconds, spent waiting in poll if data is not available. If 0, returns immediately with any records that are available now

Constructor Detail

FlinkKafkaConsumer09

public FlinkKafkaConsumer09(String topic,
                            org.apache.flink.api.common.serialization.DeserializationSchema<T> valueDeserializer,
                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x .

Parameters:

topic - The name of the topic that should be consumed.

valueDeserializer - The de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties used to configure the Kafka consumer client, and the ZooKeeper client.

FlinkKafkaConsumer09

public FlinkKafkaConsumer09(String topic,
                            org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer,
                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x

This constructor allows passing a KafkaDeserializationSchema for reading key/value pairs, offsets, and topic names from Kafka.

Parameters:

topic - The name of the topic that should be consumed.

deserializer - The keyed de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties used to configure the Kafka consumer client, and the ZooKeeper client.

FlinkKafkaConsumer09

public FlinkKafkaConsumer09(List<String> topics,
                            org.apache.flink.api.common.serialization.DeserializationSchema<T> deserializer,
                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x

This constructor allows passing multiple topics to the consumer.

Parameters:

topics - The Kafka topics to read from.

deserializer - The de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties that are used to configure both the fetcher and the offset handler.

FlinkKafkaConsumer09

public FlinkKafkaConsumer09(List<String> topics,
                            org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer,
                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x

This constructor allows passing multiple topics and a key/value deserialization schema.

Parameters:

topics - The Kafka topics to read from.

deserializer - The keyed de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties that are used to configure both the fetcher and the offset handler.

FlinkKafkaConsumer09

@PublicEvolving
public FlinkKafkaConsumer09(Pattern subscriptionPattern,
                                            org.apache.flink.api.common.serialization.DeserializationSchema<T> valueDeserializer,
                                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x. Use this constructor to subscribe to multiple topics based on a regular expression pattern.

If partition discovery is enabled (by setting a non-negative value for FlinkKafkaConsumerBase.KEY_PARTITION_DISCOVERY_INTERVAL_MILLIS in the properties), topics with names matching the pattern will also be subscribed to as they are created on the fly.

Parameters:

subscriptionPattern - The regular expression for a pattern of topic names to subscribe to.

valueDeserializer - The de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties used to configure the Kafka consumer client, and the ZooKeeper client.

FlinkKafkaConsumer09

@PublicEvolving
public FlinkKafkaConsumer09(Pattern subscriptionPattern,
                                            org.apache.flink.streaming.connectors.kafka.KafkaDeserializationSchema<T> deserializer,
                                            Properties props)

Creates a new Kafka streaming source consumer for Kafka 0.9.x. Use this constructor to subscribe to multiple topics based on a regular expression pattern.

If partition discovery is enabled (by setting a non-negative value for FlinkKafkaConsumerBase.KEY_PARTITION_DISCOVERY_INTERVAL_MILLIS in the properties), topics with names matching the pattern will also be subscribed to as they are created on the fly.

This constructor allows passing a KafkaDeserializationSchema for reading key/value pairs, offsets, and topic names from Kafka.

Parameters:

subscriptionPattern - The regular expression for a pattern of topic names to subscribe to.

deserializer - The keyed de-/serializer used to convert between Kafka's byte messages and Flink's objects.

props - The properties used to configure the Kafka consumer client, and the ZooKeeper client.

Method Detail

createFetcher

protected org.apache.flink.streaming.connectors.kafka.internals.AbstractFetcher<T,?> createFetcher(org.apache.flink.streaming.api.functions.source.SourceFunction.SourceContext<T> sourceContext,
                                                                                                   Map<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition,Long> assignedPartitionsWithInitialOffsets,
                                                                                                   org.apache.flink.util.SerializedValue<org.apache.flink.streaming.api.functions.AssignerWithPeriodicWatermarks<T>> watermarksPeriodic,
                                                                                                   org.apache.flink.util.SerializedValue<org.apache.flink.streaming.api.functions.AssignerWithPunctuatedWatermarks<T>> watermarksPunctuated,
                                                                                                   org.apache.flink.streaming.api.operators.StreamingRuntimeContext runtimeContext,
                                                                                                   org.apache.flink.streaming.connectors.kafka.config.OffsetCommitMode offsetCommitMode,
                                                                                                   org.apache.flink.metrics.MetricGroup consumerMetricGroup,
                                                                                                   boolean useMetrics)
                                                                                            throws Exception

Specified by:

createFetcher in class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

Throws:

Exception

createPartitionDiscoverer

protected org.apache.flink.streaming.connectors.kafka.internals.AbstractPartitionDiscoverer createPartitionDiscoverer(org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicsDescriptor topicsDescriptor,
                                                                                                                      int indexOfThisSubtask,
                                                                                                                      int numParallelSubtasks)

Specified by:

createPartitionDiscoverer in class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

getIsAutoCommitEnabled

protected boolean getIsAutoCommitEnabled()

Specified by:

getIsAutoCommitEnabled in class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

fetchOffsetsWithTimestamp

protected Map<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition,Long> fetchOffsetsWithTimestamp(Collection<org.apache.flink.streaming.connectors.kafka.internals.KafkaTopicPartition> partitions,
                                                                                                                        long timestamp)

Specified by:

fetchOffsetsWithTimestamp in class org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumerBase<T>

setRateLimiter

public void setRateLimiter(org.apache.flink.api.common.io.ratelimiting.FlinkConnectorRateLimiter kafkaRateLimiter)

Set a rate limiter to ratelimit bytes read from Kafka.

Parameters:

kafkaRateLimiter -

getRateLimiter

public org.apache.flink.api.common.io.ratelimiting.FlinkConnectorRateLimiter getRateLimiter()