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Reliable transactional Nakadi event producer
package org.zalando.nakadiproducer.eventlog;
import java.util.Collection;
import javax.transaction.Transactional;
import org.zalando.nakadiproducer.snapshots.SnapshotEventGenerator;
/**
* The main user interface for this library. Autowire an instance of this
* interface into your service, and call one of the methods whenever you want to
* send an event.
*
* All the methods are supposed to be called inside the same database
* transaction which also contains the corresponding changes to your business
* objects. This way it is made sure that the events are persisted if and only
* if the containing transaction is successful, sidestepping the distributed
* transaction problem.
*
*
* The library will later try to submit all those persisted events to Nakadi.
*
*/
public interface EventLogWriter {
/**
* Fires a data change event about a creation of some resource
* (object).
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event.
*
* @param data
* some POJO that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* resource which was created. It will be used as content of the
* {@code data} field of the Nakadi event.
*/
@Transactional
void fireCreateEvent(String eventType, String dataType, Object data);
/**
* Fires data change events about the creation of some resources (objects), see
* {@link #fireCreateEvent(String, String, Object) fireCreateEvent} for more details.
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event
*
* @param data
* some POJOs that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* current state of the resource. It will be used as content of
* the {@code data} field of the Nakadi event.
*/
@Transactional
void fireCreateEvents(String eventType, String dataType, Collection data);
/**
* Fires a data change event about an update of some resource (object).
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event.
*
* @param data
* some POJO that can be serialized into JSON (required
* parameter). This is meant to be a representation of the new
* state of the resource which was updated. It will be used as
* content of the {@code data} field of the Nakadi event.
*/
@Transactional
void fireUpdateEvent(String eventType, String dataType, Object data);
/**
* Fires data change events about the update of some resources (objects), see
* {@link #fireUpdateEvent(String, String, Object) fireUpdateEvent} for more details.
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event
*
* @param data
* some POJOs that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* current state of the resource. It will be used as content of
* the {@code data} field of the Nakadi event.
*/
@Transactional
void fireUpdateEvents(String eventType, String dataType, Collection data);
/**
* Fires a data change event about the deletion of some resource (object).
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event.
*
* @param data
* some POJO that can be serialized into JSON (required
* parameter). This is meant to be a representation of the last
* state (before the deletion) of the resource which was deleted.
* It will be used as content of the {@code data} field of the
* Nakadi event.
*/
@Transactional
void fireDeleteEvent(String eventType, String dataType, Object data);
/**
* Fires data change events about the deletion of some resources (objects), see
* {@link #fireDeleteEvent(String, String, Object) fireDeleteEvent} for more details.
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event
*
* @param data
* some POJOs that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* current state of the resource. It will be used as content of
* the {@code data} field of the Nakadi event.
*/
@Transactional
void fireDeleteEvents(String eventType, String dataType, Collection data);
/**
* Fires a data change event with a snapshot of some resource (object).
*
* This notifies your consumers about the current state of a resource, even
* if nothing changed. Typical use cases include initial replication to new
* consumers or hotfixes of data inconsistencies between producer and
* consumer.
*
*
* Normally applications don't have to call this themselves, instead they
* should implement the
* {@link SnapshotEventGenerator}
* interface to add support for snapshot creation via the actuator endpoint.
*
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event.
*
* @param data
* some POJO that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* current state of the resource. It will be used as content of
* the {@code data} field of the Nakadi event.
*/
@Transactional
void fireSnapshotEvent(String eventType, String dataType, Object data);
/**
* Fires data change events, see {@link #fireSnapshotEvent(String, String, Object)
* fireSnapshotEvent} for more details.
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param dataType
* the content of the {@code data_type} field of the Nakadi
* event
*
* @param data
* some POJOs that can be serialized into JSON (required
* parameter). This is meant to be a representation of the
* current state of the resource. It will be used as content of
* the {@code data} field of the Nakadi event.
*/
@Transactional
void fireSnapshotEvents(String eventType, String dataType, Collection data);
/**
* Fires a business event, i.e. an event communicating the fact that some
* business process step happened. The payload object will be used as the
* main event content (just metadata will be added). Same as for data change
* events, you should call this method in the same transaction as you are
* storing related changes into your database.
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param payload
* some POJO that can be serialized into JSON (required
* parameter)
*/
@Transactional
void fireBusinessEvent(String eventType, Object payload);
/**
* Fires business events, see {@link #fireBusinessEvent(String, Object) fireBusinessEvent} for
* more details
*
* @param eventType
* the Nakadi event type of the event. This is roughly equivalent
* to an event channel or topic.
*
* @param payloads
* some POJOs that can be serialized into JSON (required
* parameter)
*/
@Transactional
void fireBusinessEvents(String eventType, Collection payloads);
}