Package org.axonframework.eventhandling.async

Class MetaDataSequencingPolicy

java.lang.Object

org.axonframework.eventhandling.async.MetaDataSequencingPolicy

All Implemented Interfaces:

SequencingPolicy<EventMessage<?>>

public class MetaDataSequencingPolicy
extends Object
implements SequencingPolicy<EventMessage<?>>

A SequencingPolicy implementation that extracts the sequence identifier from the EventMessage's MetaData, based on a given metaDataKey. In the absence of the given metaDataKey on the MetaData, the EventMessage.getIdentifier() is used.

Since:

4.6.0

Author:

Lucas Campos

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MetaDataSequencingPolicy.Builder	Builder class to instantiate a MetaDataSequencingPolicy.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MetaDataSequencingPolicy(MetaDataSequencingPolicy.Builder builder)	Instantiate a MetaDataSequencingPolicy based on the fields contained in the MetaDataSequencingPolicy.Builder.

Method Summary

Modifier and Type	Method	Description
static MetaDataSequencingPolicy.Builder	builder()	Instantiate a Builder to be able to create a MetaDataSequencingPolicy.
Object	getSequenceIdentifierFor(EventMessage<?> event)	Returns the sequence identifier for the given event.

Methods inherited from class java.lang.Object

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

Constructor Details

MetaDataSequencingPolicy

protected MetaDataSequencingPolicy(MetaDataSequencingPolicy.Builder builder)

Instantiate a MetaDataSequencingPolicy based on the fields contained in the MetaDataSequencingPolicy.Builder.

Will assert that the metaDataKey is not null and will throw an AxonConfigurationException if this is the case.

Parameters:

builder - The MetaDataSequencingPolicy.Builder used to instantiate a MetaDataSequencingPolicy instance.

Method Details

builder

public static MetaDataSequencingPolicy.Builder builder()

Instantiate a Builder to be able to create a MetaDataSequencingPolicy.

The following fields of this builder are hard requirements and as such should be provided:

• The metaDataKey key to be used as a lookup for the property to be used as the Sequence Policy.

Returns:

A Builder to be able to create a MetaDataSequencingPolicy.

getSequenceIdentifierFor

public Object getSequenceIdentifierFor(@Nonnull
 EventMessage<?> event)

Description copied from interface: SequencingPolicy

Returns the sequence identifier for the given event. When two events have the same identifier (as defined by their equals method), they will be executed sequentially. A null value indicates that there are no sequencing requirements for the handling of this event.

Specified by:

getSequenceIdentifierFor in interface SequencingPolicy<EventMessage<?>>

Parameters:

event - the event for which to get the sequencing identifier

Returns:

a sequence identifier for the given event