org.axonframework.modelling.saga

Class AbstractSagaManager<T>

java.lang.Object

org.axonframework.modelling.saga.AbstractSagaManager<T>

All Implemented Interfaces:

EventHandlerInvoker, ScopeAware

Direct Known Subclasses:

AnnotatedSagaManager

public abstract class AbstractSagaManager<T>
extends Object
implements EventHandlerInvoker, ScopeAware

Abstract implementation of the SagaManager interface that provides basic functionality required by most SagaManager implementations. Provides support for Saga lifecycle management and asynchronous handling of events.

Since:

0.7

Author:

Allard Buijze

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractSagaManager.Builder<T> Abstract Builder class to instantiate AbstractSagaManager implementations.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractSagaManager(AbstractSagaManager.Builder<T> builder) Instantiate a AbstractSagaManager based on the fields contained in the AbstractSagaManager.Builder.

Method Summary

Modifier and Type	Method and Description
boolean	canResolve(ScopeDescriptor scopeDescription) Check whether this implementation can resolve a Scope object based on the provided scopeDescription.
protected String	createSagaIdentifier(Segment segment) Creates a Saga identifier that will cause a Saga instance to be considered part of the given segment.
protected abstract Set<AssociationValue>	extractAssociationValues(EventMessage<?> event) Extracts the AssociationValues from the given event as relevant for a Saga of given sagaType.
protected abstract SagaInitializationPolicy	getSagaCreationPolicy(EventMessage<?> event) Returns the Saga Initialization Policy for a Saga of the given sagaType and event.
Class<T>	getSagaType() Returns the class of Saga managed by this SagaManager
void	handle(EventMessage<?> event, Segment segment) Handle the given message for the given segment.
protected boolean	matchesSegment(Segment segment, String sagaId) Checks whether the given sagaId matches with the given segment.
void	performReset() Performs any activities that are required to reset the state managed by handlers assigned to this invoker.
void	send(Message<?> message, ScopeDescriptor scopeDescription) Send a Message to a Scope which is described by the given scopeDescription.
boolean	supportsReset() Indicates whether the handlers managed by this invoker support a reset.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.eventhandling.EventHandlerInvoker

canHandle, canHandleType

Constructor Detail

AbstractSagaManager

protected AbstractSagaManager(AbstractSagaManager.Builder<T> builder)

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

Will assert that the sagaType, sagaFactory, SagaRepository and ListenerInvocationErrorHandler are not null, and will throw an AxonConfigurationException if any of them is null.

Parameters:

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

Method Detail

handle

public void handle(EventMessage<?> event,
                   Segment segment)
            throws Exception

Description copied from interface: EventHandlerInvoker

Handle the given message for the given segment.

Callers are recommended to invoke EventHandlerInvoker.canHandle(EventMessage, Segment) prior to invocation, but aren't required to do so. Implementations must ensure to take the given segment into account when processing messages.

Specified by:

handle in interface EventHandlerInvoker

Parameters:

event - The message to handle

segment - The segment for which to handle the message

Throws:

Exception - when an exception occurs while handling the message

createSagaIdentifier

protected String createSagaIdentifier(Segment segment)

Creates a Saga identifier that will cause a Saga instance to be considered part of the given segment.

Parameters:

segment - The segment the identifier must match with

Returns:

an identifier for a newly created Saga

Implementation Requirements:

This implementation will repeatedly generate identifier using the IdentifierFactory, until one is returned that matches the given segment. See matchesSegment(Segment, String).

matchesSegment

protected boolean matchesSegment(Segment segment,
                                 String sagaId)

Checks whether the given sagaId matches with the given segment.

For any complete set of segments, exactly one segment matches with any value.

Parameters:

segment - The segment to validate the identifier for

sagaId - The identifier to test

Returns:

true if the identifier matches the segment, otherwise false

Implementation Requirements:

This implementation uses the Segment.matches(Object) to match against the Saga identifier

getSagaCreationPolicy

protected abstract SagaInitializationPolicy getSagaCreationPolicy(EventMessage<?> event)

Returns the Saga Initialization Policy for a Saga of the given sagaType and event. This policy provides the conditions to create new Saga instance, as well as the initial association of that saga.

Parameters:

event - The Event that is being dispatched to Saga instances

Returns:

the initialization policy for the Saga

extractAssociationValues

protected abstract Set<AssociationValue> extractAssociationValues(EventMessage<?> event)

Extracts the AssociationValues from the given event as relevant for a Saga of given sagaType. A single event may be associated with multiple values.

Parameters:

event - The event containing the association information

Returns:

the AssociationValues indicating which Sagas should handle given event

getSagaType

public Class<T> getSagaType()

Returns the class of Saga managed by this SagaManager

Returns:

the managed saga type

supportsReset

public boolean supportsReset()

Description copied from interface: EventHandlerInvoker

Indicates whether the handlers managed by this invoker support a reset.

Specified by:

supportsReset in interface EventHandlerInvoker

Returns:

true if a reset is supported, otherwise false

performReset

public void performReset()

Description copied from interface: EventHandlerInvoker

Performs any activities that are required to reset the state managed by handlers assigned to this invoker.

Specified by:

performReset in interface EventHandlerInvoker

send

public void send(Message<?> message,
                 ScopeDescriptor scopeDescription)
          throws Exception

Description copied from interface: ScopeAware

Send a Message to a Scope which is described by the given scopeDescription.

Specified by:

send in interface ScopeAware

Parameters:

message - a Message to be send to a Scope

scopeDescription - a D extending ScopeDescriptor, describing the Scope to send the given message to

Throws:

Exception - if sending the message failed. Might occur if the message handling process throws an exception

canResolve

public boolean canResolve(ScopeDescriptor scopeDescription)

Description copied from interface: ScopeAware

Check whether this implementation can resolve a Scope object based on the provided scopeDescription. Will return true in case it should be able to resolve the Scope and false if it cannot.

Specified by:

canResolve in interface ScopeAware

Parameters:

scopeDescription - a ScopeDescriptor describing the Scope to be resolved

Returns:

true in case it should be able to resolve the Scope and false if it cannot