Package org.axonframework.eventhandling.async

Class PropertySequencingPolicy<T,K>

java.lang.Object

org.axonframework.eventhandling.async.PropertySequencingPolicy<T,K>

Type Parameters:

T - The type of the supported event payloads.

K - The type of the extracted property.

All Implemented Interfaces:

SequencingPolicy<EventMessage>

public class PropertySequencingPolicy<T,K>
extends Object
implements SequencingPolicy<EventMessage>

A SequencingPolicy implementation that extracts the sequence identifier from the event message payload based on a given property or property extractor. If the event message payload is not of a supported type, a fallback sequencing policy is used. By default the fallback sequencing policy raises an exception.

Since:

4.5.2

Author:

Nils Christian Ehmke

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	PropertySequencingPolicy.Builder<T,K>	Builder class to instantiate a PropertySequencingPolicy.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
static <T, K> PropertySequencingPolicy.Builder<T,K>	builder(Class<T> payloadClass, Class<K> propertyClass)	Instantiate a Builder to be able to create a PropertySequencingPolicy.
Object	getSequenceIdentifierFor(EventMessage eventMessage)	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

PropertySequencingPolicy

protected PropertySequencingPolicy(PropertySequencingPolicy.Builder builder)

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

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

Parameters:

builder - the PropertySequencingPolicy.Builder used to instantiate a PropertySequencingPolicy instance

Method Details

getSequenceIdentifierFor

public Object getSequenceIdentifierFor(@Nonnull
 EventMessage eventMessage)

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<T>

Parameters:

eventMessage - the event for which to get the sequencing identifier

Returns:

a sequence identifier for the given event

builder

public static <T,
K>
PropertySequencingPolicy.Builder<T,K> builder(Class<T> payloadClass,
 Class<K> propertyClass)

Instantiate a Builder to be able to create a PropertySequencingPolicy.

Upon initialization of this builder, the following fields are defaulted:

• The fallbackSequencingPolicy defaults to an exception raising sequencing policy.

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

• The payloadClass which defines the supported type of event message payload.
• The propertyExtractor which is applied to the payload and extract the sequence identifier.
• The fallbackSequencingPolicy which defines the behaviour in case of an unsupported event payload.

Type Parameters:

T - the type of the supported event payloads

K - the type of the extracted property

Parameters:

payloadClass - the class of the supported event payloads

propertyClass - the class of the extracted property

Returns:

a Builder to be able to create a PropertySequencingPolicy