org.apache.beam.sdk.io.kafka

Class KafkaIO.Read<K,V>

java.lang.Object

org.apache.beam.sdk.transforms.PTransform<PBegin,PCollection<KafkaRecord<K,V>>>

org.apache.beam.sdk.io.kafka.KafkaIO.Read<K,V>

All Implemented Interfaces:

java.io.Serializable, HasDisplayData

Enclosing class:

KafkaIO

public abstract static class KafkaIO.Read<K,V>
extends PTransform<PBegin,PCollection<KafkaRecord<K,V>>>

A PTransform to read from Kafka topics. See KafkaIO for more information on usage and configuration.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

name

Constructor Summary

Constructors

Constructor and Description
Read()

Method Summary

Modifier and Type	Method and Description
PCollection<KafkaRecord<K,V>>	expand(PBegin input) Applies this PTransform on the given InputT, and returns its Output.
void	populateDisplayData(DisplayData.Builder builder) Register display data for the given transform or component.
KafkaIO.Read<K,V>	updateConsumerProperties(java.util.Map<java.lang.String,java.lang.Object> configUpdates) Update consumer configuration with new properties.
void	validate(PipelineOptions options) Called before running the Pipeline to verify this transform is fully and correctly specified.
KafkaIO.Read<K,V>	withBootstrapServers(java.lang.String bootstrapServers) Sets the bootstrap servers for the Kafka consumer.
KafkaIO.Read<K,V>	withConsumerFactoryFn(SerializableFunction<java.util.Map<java.lang.String,java.lang.Object>,org.apache.kafka.clients.consumer.Consumer<byte[],byte[]>> consumerFactoryFn) A factory to create Kafka Consumer from consumer configuration.
KafkaIO.Read<K,V>	withKeyDeserializer(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<K>> keyDeserializer) Sets a Kafka Deserializer to interpret key bytes read from Kafka.
KafkaIO.Read<K,V>	withKeyDeserializerAndCoder(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<K>> keyDeserializer, Coder<K> keyCoder) Sets a Kafka Deserializer for interpreting key bytes read from Kafka along with a Coder for helping the Beam runner materialize key objects at runtime if necessary.
KafkaIO.Read<K,V>	withMaxNumRecords(long maxNumRecords) Similar to Read.Unbounded.withMaxNumRecords(long).
KafkaIO.Read<K,V>	withMaxReadTime(Duration maxReadTime) Similar to Read.Unbounded.withMaxReadTime(Duration).
PTransform<PBegin,PCollection<KV<K,V>>>	withoutMetadata() Returns a PTransform for PCollection of KV, dropping Kafka metatdata.
KafkaIO.Read<K,V>	withTimestampFn(SerializableFunction<KV<K,V>,Instant> timestampFn) A function to assign a timestamp to a record.
KafkaIO.Read<K,V>	withTimestampFn2(SerializableFunction<KafkaRecord<K,V>,Instant> timestampFn) A function to assign a timestamp to a record.
KafkaIO.Read<K,V>	withTopic(java.lang.String topic) Sets the topic to read from.
KafkaIO.Read<K,V>	withTopicPartitions(java.util.List<org.apache.kafka.common.TopicPartition> topicPartitions) Sets a list of partitions to read from.
KafkaIO.Read<K,V>	withTopics(java.util.List<java.lang.String> topics) Sets a list of topics to read from.
KafkaIO.Read<K,V>	withValueDeserializer(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<V>> valueDeserializer) Sets a Kafka Deserializer to interpret value bytes read from Kafka.
KafkaIO.Read<K,V>	withValueDeserializerAndCoder(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<V>> valueDeserializer, Coder<V> valueCoder) Sets a Kafka Deserializer for interpreting value bytes read from Kafka along with a Coder for helping the Beam runner materialize value objects at runtime if necessary.
KafkaIO.Read<K,V>	withWatermarkFn(SerializableFunction<KV<K,V>,Instant> watermarkFn) A function to calculate watermark after a record.
KafkaIO.Read<K,V>	withWatermarkFn2(SerializableFunction<KafkaRecord<K,V>,Instant> watermarkFn) A function to calculate watermark after a record.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

getAdditionalInputs, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Read

public Read()

Method Detail

withBootstrapServers

public KafkaIO.Read<K,V> withBootstrapServers(java.lang.String bootstrapServers)

Sets the bootstrap servers for the Kafka consumer.

withTopic

public KafkaIO.Read<K,V> withTopic(java.lang.String topic)

Sets the topic to read from.

See UnboundedKafkaSource#split(int, PipelineOptions) for description of how the partitions are distributed among the splits.

withTopics

public KafkaIO.Read<K,V> withTopics(java.util.List<java.lang.String> topics)

Sets a list of topics to read from. All the partitions from each of the topics are read.

See UnboundedKafkaSource#split(int, PipelineOptions) for description of how the partitions are distributed among the splits.

withTopicPartitions

public KafkaIO.Read<K,V> withTopicPartitions(java.util.List<org.apache.kafka.common.TopicPartition> topicPartitions)

Sets a list of partitions to read from. This allows reading only a subset of partitions for one or more topics when (if ever) needed.

See UnboundedKafkaSource#split(int, PipelineOptions) for description of how the partitions are distributed among the splits.

withKeyDeserializer

public KafkaIO.Read<K,V> withKeyDeserializer(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<K>> keyDeserializer)

Sets a Kafka Deserializer to interpret key bytes read from Kafka.

In addition, Beam also needs a Coder to serialize and deserialize key objects at runtime. KafkaIO tries to infer a coder for the key based on the Deserializer class, however in case that fails, you can use withKeyDeserializerAndCoder(Class, Coder) to provide the key coder explicitly.

withKeyDeserializerAndCoder

public KafkaIO.Read<K,V> withKeyDeserializerAndCoder(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<K>> keyDeserializer,
                                                     Coder<K> keyCoder)

Sets a Kafka Deserializer for interpreting key bytes read from Kafka along with a Coder for helping the Beam runner materialize key objects at runtime if necessary.

Use this method only if your pipeline doesn't work with plain withKeyDeserializer(Class).

withValueDeserializer

public KafkaIO.Read<K,V> withValueDeserializer(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<V>> valueDeserializer)

Sets a Kafka Deserializer to interpret value bytes read from Kafka.

In addition, Beam also needs a Coder to serialize and deserialize value objects at runtime. KafkaIO tries to infer a coder for the value based on the Deserializer class, however in case that fails, you can use withValueDeserializerAndCoder(Class, Coder) to provide the value coder explicitly.

withValueDeserializerAndCoder

public KafkaIO.Read<K,V> withValueDeserializerAndCoder(java.lang.Class<? extends org.apache.kafka.common.serialization.Deserializer<V>> valueDeserializer,
                                                       Coder<V> valueCoder)

Sets a Kafka Deserializer for interpreting value bytes read from Kafka along with a Coder for helping the Beam runner materialize value objects at runtime if necessary.

Use this method only if your pipeline doesn't work with plain withValueDeserializer(Class).

withConsumerFactoryFn

public KafkaIO.Read<K,V> withConsumerFactoryFn(SerializableFunction<java.util.Map<java.lang.String,java.lang.Object>,org.apache.kafka.clients.consumer.Consumer<byte[],byte[]>> consumerFactoryFn)

A factory to create Kafka Consumer from consumer configuration. This is useful for supporting another version of Kafka consumer. Default is KafkaConsumer.

updateConsumerProperties

public KafkaIO.Read<K,V> updateConsumerProperties(java.util.Map<java.lang.String,java.lang.Object> configUpdates)

Update consumer configuration with new properties.

withMaxNumRecords

public KafkaIO.Read<K,V> withMaxNumRecords(long maxNumRecords)

Similar to Read.Unbounded.withMaxNumRecords(long). Mainly used for tests and demo applications.

withMaxReadTime

public KafkaIO.Read<K,V> withMaxReadTime(Duration maxReadTime)

Similar to Read.Unbounded.withMaxReadTime(Duration). Mainly used for tests and demo applications.

withTimestampFn2

public KafkaIO.Read<K,V> withTimestampFn2(SerializableFunction<KafkaRecord<K,V>,Instant> timestampFn)

A function to assign a timestamp to a record. Default is processing timestamp.

withWatermarkFn2

public KafkaIO.Read<K,V> withWatermarkFn2(SerializableFunction<KafkaRecord<K,V>,Instant> watermarkFn)

A function to calculate watermark after a record. Default is last record timestamp

See Also:

withTimestampFn(SerializableFunction)

withTimestampFn

public KafkaIO.Read<K,V> withTimestampFn(SerializableFunction<KV<K,V>,Instant> timestampFn)

A function to assign a timestamp to a record. Default is processing timestamp.

withWatermarkFn

public KafkaIO.Read<K,V> withWatermarkFn(SerializableFunction<KV<K,V>,Instant> watermarkFn)

A function to calculate watermark after a record. Default is last record timestamp

See Also:

withTimestampFn(SerializableFunction)

withoutMetadata

public PTransform<PBegin,PCollection<KV<K,V>>> withoutMetadata()

Returns a PTransform for PCollection of KV, dropping Kafka metatdata.

validate

public void validate(PipelineOptions options)

Description copied from class: PTransform

Called before running the Pipeline to verify this transform is fully and correctly specified.

By default, does nothing.

Overrides:

validate in class PTransform<PBegin,PCollection<KafkaRecord<K,V>>>

expand

public PCollection<KafkaRecord<K,V>> expand(PBegin input)

Description copied from class: PTransform

Applies this PTransform on the given InputT, and returns its Output.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

Specified by:

expand in class PTransform<PBegin,PCollection<KafkaRecord<K,V>>>

populateDisplayData

public void populateDisplayData(DisplayData.Builder builder)

Description copied from class: PTransform

Register display data for the given transform or component.

populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

By default, does not register any display data. Implementors may override this method to provide their own display data.

Specified by:

populateDisplayData in interface HasDisplayData

Overrides:

populateDisplayData in class PTransform<PBegin,PCollection<KafkaRecord<K,V>>>

Parameters:

builder - The builder to populate with display data.

See Also:

HasDisplayData