org.axonframework.kafka.eventhandling.consumer

Class KafkaMessageStream

java.lang.Object

org.axonframework.kafka.eventhandling.consumer.KafkaMessageStream

All Implemented Interfaces:

AutoCloseable, TrackingEventStream, MessageStream<TrackedEventMessage<?>>

public class KafkaMessageStream
extends Object
implements TrackingEventStream

Create message stream from a specific kafka topic. Messages are fetch in bulk and stored in an in-memory buffer. We try to introduce some sort and stored them in a local buffer. Consumer position is tracked via KafkaTrackingTokenRecords are fetched from kafka and stored in-memory buffer.

This is not thread safe

Since:

3.0

Author:

Allard Buijze, Nakul Mishra

Constructor Summary

Constructors

Constructor and Description
KafkaMessageStream(Buffer<KafkaEventMessage> buffer, Runnable closeHandler)

Method Summary

Modifier and Type	Method and Description
void	close()
boolean	hasNextAvailable(int timeout, TimeUnit unit) Checks whether or not the next message in the stream is available.
TrackedEventMessage<?>	nextAvailable() Returns the next available message in the stream.
Optional<TrackedEventMessage<?>>	peek() Checks whether or not the next message in the stream is immediately available.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.messaging.MessageStream

asStream, hasNextAvailable

Constructor Detail

KafkaMessageStream

public KafkaMessageStream(Buffer<KafkaEventMessage> buffer,
                          Runnable closeHandler)

Method Detail

peek

public Optional<TrackedEventMessage<?>> peek()

Description copied from interface: MessageStream

Checks whether or not the next message in the stream is immediately available. If so, an Optional with the next message is returned (without moving the stream pointer), otherwise an empty Optional is returned.

Specified by:

peek in interface MessageStream<TrackedEventMessage<?>>

Returns:

the next event if immediately available

hasNextAvailable

public boolean hasNextAvailable(int timeout,
                                TimeUnit unit)

Description copied from interface: MessageStream

Checks whether or not the next message in the stream is available. If a message is available when this method is invoked this method returns immediately. If not, this method will block until a message becomes available, returning true or until the given timeout expires, returning false.

To check if the stream has messages available now, pass a zero timeout.

Specified by:

hasNextAvailable in interface MessageStream<TrackedEventMessage<?>>

Parameters:

timeout - the maximum number of time units to wait for messages to become available

unit - the time unit for the timeout

Returns:

true if a message is available or becomes available before the given timeout, false otherwise

nextAvailable

public TrackedEventMessage<?> nextAvailable()

Description copied from interface: MessageStream

Returns the next available message in the stream. Note that this method blocks for as long as there are no available messages in the stream. In case this blocking behavior is not desired use MessageStream.hasNextAvailable() with or without a timeout to check if the stream has available messages before calling this method.

Specified by:

nextAvailable in interface MessageStream<TrackedEventMessage<?>>

Returns:

the next available message

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface MessageStream<TrackedEventMessage<?>>