org.apache.storm.kafka.bolt

Class KafkaBolt<K,V>

java.lang.Object

org.apache.storm.topology.base.BaseComponent

org.apache.storm.topology.base.BaseRichBolt

org.apache.storm.topology.base.BaseTickTupleAwareRichBolt

org.apache.storm.kafka.bolt.KafkaBolt<K,V>

All Implemented Interfaces:

Serializable, IBolt, IComponent, IRichBolt

public class KafkaBolt<K,V>
extends BaseTickTupleAwareRichBolt

Bolt implementation that can send Tuple data to Kafka.

Most configuration for this bolt should be through the various setter methods in the bolt. For backwards compatibility it supports the producer configuration and topic to be placed in the storm config under

‘kafka.broker.properties’ and ‘topic’

respectively.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	TOPIC

Constructor Summary

Constructors

Constructor and Description
KafkaBolt()

Method Summary

Modifier and Type	Method and Description
void	cleanup() Called when an IBolt is going to be shutdown.
void	declareOutputFields(OutputFieldsDeclarer declarer) Declare the output schema for all the streams of this topology.
protected org.apache.kafka.clients.producer.Producer<K,V>	mkProducer(Properties props) Intended to be overridden for tests.
void	prepare(Map<String,Object> topoConf, TopologyContext context, OutputCollector collector) Called when a task for this component is initialized within a worker on the cluster.
protected void	process(Tuple input) Process a single non-tick tuple of input.
void	setAsync(boolean async) If set to true(the default) the bolt will not wait for the message to be fully sent to Kafka before getting another tuple to send.
void	setFireAndForget(boolean fireAndForget) If set to true the bolt will assume that sending a message to kafka will succeed and will ack the tuple as soon as it has handed the message off to the producer API if false (the default) the message will be acked after it was successfully sent to kafka or failed if it was not successfully sent.
String	toString()
KafkaBolt<K,V>	withProducerCallback(PreparableCallback producerCallback) Sets a user defined callback for use with the KafkaProducer.
KafkaBolt<K,V>	withProducerProperties(Properties producerProperties)
KafkaBolt<K,V>	withTopicSelector(KafkaTopicSelector selector)
KafkaBolt<K,V>	withTopicSelector(String topic) Set the messages to be published to a single topic.
KafkaBolt<K,V>	withTupleToKafkaMapper(TupleToKafkaMapper<K,V> mapper)

Methods inherited from class org.apache.storm.topology.base.BaseTickTupleAwareRichBolt

execute, onTickTuple

Methods inherited from class org.apache.storm.topology.base.BaseComponent

getComponentConfiguration

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.storm.topology.IComponent

getComponentConfiguration

Field Detail

TOPIC

public static final String TOPIC

See Also:

Constant Field Values

Constructor Detail

KafkaBolt

public KafkaBolt()

Method Detail

withTupleToKafkaMapper

public KafkaBolt<K,V> withTupleToKafkaMapper(TupleToKafkaMapper<K,V> mapper)

withTopicSelector

public KafkaBolt<K,V> withTopicSelector(String topic)

Set the messages to be published to a single topic.

Parameters:

topic - the topic to publish to

Returns:

this

withTopicSelector

public KafkaBolt<K,V> withTopicSelector(KafkaTopicSelector selector)

withProducerProperties

public KafkaBolt<K,V> withProducerProperties(Properties producerProperties)

withProducerCallback

public KafkaBolt<K,V> withProducerCallback(PreparableCallback producerCallback)

Sets a user defined callback for use with the KafkaProducer.

Parameters:

producerCallback - user defined callback

Returns:

this

prepare

public void prepare(Map<String,Object> topoConf,
                    TopologyContext context,
                    OutputCollector collector)

Description copied from interface: IBolt

Called when a task for this component is initialized within a worker on the cluster. It provides the bolt with the environment in which the bolt executes.

This includes the:

Parameters:

topoConf - The Storm configuration for this bolt. This is the configuration provided to the topology merged in with cluster configuration on this machine.

context - This object can be used to get information about this task’s place within the topology, including the task id and component id of this task, input and output information, etc.

collector - The collector is used to emit tuples from this bolt. Tuples can be emitted at any time, including the prepare and cleanup methods. The collector is thread-safe and should be saved as an instance variable of this bolt object.

mkProducer

protected org.apache.kafka.clients.producer.Producer<K,V> mkProducer(Properties props)

Intended to be overridden for tests. Make the producer with the given props

process

protected void process(Tuple input)

Description copied from class: BaseTickTupleAwareRichBolt

Process a single non-tick tuple of input. Implementation needs to handle ack manually. More details on IBolt.execute(Tuple).

Specified by:

process in class BaseTickTupleAwareRichBolt

Parameters:

input - The input tuple to be processed.

declareOutputFields

public void declareOutputFields(OutputFieldsDeclarer declarer)

Description copied from interface: IComponent

Declare the output schema for all the streams of this topology.

Parameters:

declarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream

cleanup

public void cleanup()

Description copied from interface: IBolt

Called when an IBolt is going to be shutdown. Storm will make a best-effort attempt to call this if the worker shutdown is orderly. The Config.SUPERVISOR_WORKER_SHUTDOWN_SLEEP_SECS setting controls how long orderly shutdown is allowed to take. There is no guarantee that cleanup will be called if shutdown is not orderly, or if the shutdown exceeds the time limit.

The one context where cleanup is guaranteed to be called is when a topology is killed when running Storm in local mode.

Specified by:

cleanup in interface IBolt

Overrides:

cleanup in class BaseRichBolt

setFireAndForget

public void setFireAndForget(boolean fireAndForget)

If set to true the bolt will assume that sending a message to kafka will succeed and will ack the tuple as soon as it has handed the message off to the producer API if false (the default) the message will be acked after it was successfully sent to kafka or failed if it was not successfully sent.

Parameters:

fireAndForget - whether the bolt should fire and forget

setAsync

public void setAsync(boolean async)

If set to true(the default) the bolt will not wait for the message to be fully sent to Kafka before getting another tuple to send.

Parameters:

async - true to have multiple tuples in flight to kafka, else false.

toString

public String toString()

Overrides:

toString in class Object