org.apache.sling.distribution.journal

Interface MessagingProvider

public interface MessagingProvider

Messaging abstraction for a journal based messaging like Apache Kafka. Messages are represented as json serialisable java classes. The API assumes that each MessagingProvider is mapped to exactly one partition, so positions in a topic can be represented as a single long offset.

Method Summary

Modifier and Type	Method and Description
void	assertTopic(String topic) Validate that a topic is suitably set up for the messaging implementation
String	assignTo(long offset) Create assign String to feed into poller based on a given offset.
String	assignTo(Reset reset, long relativeOffset) Get assign String to feed into createPoller based on either earliest or latest and a relative offset.
default Closeable	createPoller(String topicName, Reset reset, HandlerAdapter<?>... adapters)
Closeable	createPoller(String topicName, Reset reset, String assign, HandlerAdapter<?>... adapters) Create a poller which listens to a topic and starts at a given reset or assigned offset.
<T> MessageSender<T>	createSender(String topic) Create sender for a specific topic
URI	getServerUri() Return the uri of the messaging system backend.
long	retrieveOffset(String topicName, Reset reset) Retrieve earliest or latest offset for a topic

Method Detail

createSender

<T> MessageSender<T> createSender(String topic)

Create sender for a specific topic

Type Parameters:

T - type of the message

Parameters:

topic - topic name

Returns:

sender

createPoller

default Closeable createPoller(String topicName,
                               Reset reset,
                               HandlerAdapter<?>... adapters)

createPoller

Closeable createPoller(String topicName,
                       Reset reset,
                       String assign,
                       HandlerAdapter<?>... adapters)

Create a poller which listens to a topic and starts at a given reset or assigned offset.

Parameters:

topicName - name of the topic

reset - fallback in case no assign is given or the assigned offset not valid

assign - opaque implementation dependent assign string (can be null)

adapters - list of listener adapters

Returns:

closeable handle of the poller

assertTopic

void assertTopic(String topic)
          throws MessagingException

Validate that a topic is suitably set up for the messaging implementation

Parameters:

topic - topic name

Throws:

MessagingException - exception in case the topic is not suitable

retrieveOffset

long retrieveOffset(String topicName,
                    Reset reset)

Retrieve earliest or latest offset for a topic

Parameters:

topicName - name of the topic

reset - latest or earliest

Returns:

offset

assignTo

String assignTo(long offset)

Create assign String to feed into poller based on a given offset. The inner format of the assign string is implementation specific.

Parameters:

offset -

Returns:

assign String

assignTo

String assignTo(Reset reset,
                long relativeOffset)

Get assign String to feed into createPoller based on either earliest or latest and a relative offset. The inner format of the assign string is implementation specific.

Parameters:

reset - reference point

relativeOffset - relative offset

Returns:

assign String

getServerUri

URI getServerUri()

Return the uri of the messaging system backend. The uri must be unique regarding the validity of per topic offsets.

Returns:

uri