org.apache.kafka.connect.source

Class SourceTask

java.lang.Object

org.apache.kafka.connect.source.SourceTask

All Implemented Interfaces:

Task

public abstract class SourceTask
extends Object
implements Task

SourceTask is a Task that pulls records from another system for storage in Kafka.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SourceTask.TransactionBoundary Represents the permitted values for the TRANSACTION_BOUNDARY_CONFIG property.

Field Summary

Fields

Modifier and Type	Field and Description
static String	TRANSACTION_BOUNDARY_CONFIG The configuration key that determines how source tasks will define transaction boundaries when exactly-once support is enabled.

Constructor Summary

Constructors

Constructor and Description
SourceTask()

Method Summary

Modifier and Type	Method and Description
void	commit() This method is invoked periodically when offsets are committed for this source task.
void	commitRecord(SourceRecord record) Deprecated. Use commitRecord(SourceRecord, RecordMetadata) instead.
void	commitRecord(SourceRecord record, org.apache.kafka.clients.producer.RecordMetadata metadata) Commit an individual SourceRecord when the callback from the producer client is received.
void	initialize(SourceTaskContext context) Initialize this SourceTask with the specified context object.
abstract List<SourceRecord>	poll() Poll this source task for new records.
abstract void	start(Map<String,String> props) Start the Task.
abstract void	stop() Signal this SourceTask to stop.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.kafka.connect.connector.Task

version

Field Detail

TRANSACTION_BOUNDARY_CONFIG

public static final String TRANSACTION_BOUNDARY_CONFIG

The configuration key that determines how source tasks will define transaction boundaries when exactly-once support is enabled.

See Also:

Constant Field Values

Constructor Detail

SourceTask

public SourceTask()

Method Detail

initialize

public void initialize(SourceTaskContext context)

Initialize this SourceTask with the specified context object.

start

public abstract void start(Map<String,String> props)

Start the Task. This should handle any configuration parsing and one-time setup of the task.

Specified by:

start in interface Task

Parameters:

props - initial configuration

poll

public abstract List<SourceRecord> poll()
                                 throws InterruptedException

Poll this source task for new records. If no data is currently available, this method should block but return control to the caller regularly (by returning null) in order for the task to transition to the PAUSED state if requested to do so.

The task will be stopped on a separate thread, and when that happens this method is expected to unblock, quickly finish up any remaining processing, and return.

Returns:

a list of source records

Throws:

InterruptedException

commit

public void commit()
            throws InterruptedException

This method is invoked periodically when offsets are committed for this source task. Note that the offsets being committed won't necessarily correspond to the latest offsets returned by this source task via poll(). Also see commitRecord(SourceRecord, RecordMetadata) which allows for a more fine-grained tracking of records that have been successfully delivered.

SourceTasks are not required to implement this functionality; Kafka Connect will record offsets automatically. This hook is provided for systems that also need to store offsets internally in their own system.

Throws:

InterruptedException

stop

public abstract void stop()

Signal this SourceTask to stop. In SourceTasks, this method only needs to signal to the task that it should stop trying to poll for new data and interrupt any outstanding poll() requests. It is not required that the task has fully stopped. Note that this method necessarily may be invoked from a different thread than poll() and commit().

For example, if a task uses a Selector to receive data over the network, this method could set a flag that will force poll() to exit immediately and invoke wakeup() to interrupt any ongoing requests.

Specified by:

stop in interface Task

commitRecord

@Deprecated
public void commitRecord(SourceRecord record)
                              throws InterruptedException

Deprecated. Use commitRecord(SourceRecord, RecordMetadata) instead.

Commit an individual SourceRecord when the callback from the producer client is received. This method is also called when a record is filtered by a transformation, and thus will never be ACK'd by a broker.

This is an alias for commitRecord(SourceRecord, RecordMetadata) for backwards compatibility. The default implementation of commitRecord(SourceRecord, RecordMetadata) just calls this method. It is not necessary to override both methods.

SourceTasks are not required to implement this functionality; Kafka Connect will record offsets automatically. This hook is provided for systems that also need to store offsets internally in their own system.

Parameters:

record - SourceRecord that was successfully sent via the producer or filtered by a transformation

Throws:

InterruptedException

commitRecord

public void commitRecord(SourceRecord record,
                         org.apache.kafka.clients.producer.RecordMetadata metadata)
                  throws InterruptedException

Commit an individual SourceRecord when the callback from the producer client is received. This method is also called when a record is filtered by a transformation or when "errors.tolerance" is set to "all" and thus will never be ACK'd by a broker. In both cases metadata will be null.

SourceTasks are not required to implement this functionality; Kafka Connect will record offsets automatically. This hook is provided for systems that also need to store offsets internally in their own system.

The default implementation just calls commitRecord(SourceRecord), which is a nop by default. It is not necessary to implement both methods.

Parameters:

record - SourceRecord that was successfully sent via the producer, filtered by a transformation, or dropped on producer exception

metadata - RecordMetadata record metadata returned from the broker, or null if the record was filtered or if producer exceptions are ignored

Throws:

InterruptedException