org.axonframework.eventhandling.saga

Interface Saga<T>

All Known Implementing Classes:

AnnotatedSaga

public interface Saga<T>

Interface describing an implementation of a Saga. Sagas are instances that handle events and may possibly produce new commands or have other side effects. Typically, Sagas are used to manage long running business transactions.

Multiple instances of a single type of Saga may exist. In that case, each Saga will be managing a different transaction. Sagas need to be associated with concepts in order to receive specific events. These associations are managed through AssociationValues. For example, to associate a saga with an Order with ID 1234, this saga needs an association value with key "orderId" and value "1234".

Since:

0.7

Author:

Allard Buijze

Method Summary

Modifier and Type	Method and Description
void	execute(Consumer<T> invocation) Execute the given invocation against the root object of this Saga instance.
AssociationValues	getAssociationValues() Returns a view on the Association Values for this saga instance.
String	getSagaIdentifier() Returns the unique identifier of this saga.
boolean	handle(EventMessage<?> event) Handle the given event.
<R> R	invoke(Function<T,R> invocation) Execute the given invocation against the root object of this Saga instance.
boolean	isActive() Indicates whether or not this saga is active.
TrackingToken	trackingToken() Returns the TrackingToken belonging to the EventMessage last processed by this instance, or null if this instance never handled an EventMessage, or if it received an EventMessage that doesn't carry a TrackingToken.

Method Detail

getSagaIdentifier

String getSagaIdentifier()

Returns the unique identifier of this saga.

Returns:

the unique identifier of this saga

getAssociationValues

AssociationValues getAssociationValues()

Returns a view on the Association Values for this saga instance. The returned instance is mutable.

Returns:

a view on the Association Values for this saga instance

invoke

<R> R invoke(Function<T,R> invocation)

Execute the given invocation against the root object of this Saga instance.

Type Parameters:

R - The type of return value expected

Parameters:

invocation - the function to invoke. The root object of the Saga is input to the function, the result is the result of the execution.

Returns:

The result of the invocation on the Saga.

execute

void execute(Consumer<T> invocation)

Execute the given invocation against the root object of this Saga instance.

Parameters:

invocation - the function to invoke. The root object of the Saga is input to the function.

handle

boolean handle(EventMessage<?> event)

Handle the given event. The actual result of processing depends on the implementation of the saga.

Implementations are highly discouraged from throwing exceptions.

Parameters:

event - the event to handle

Returns:

true if the event was handled by the Saga, otherwise false

isActive

boolean isActive()

Indicates whether or not this saga is active. A Saga is active when its life cycle has not been ended.

Returns:

true if this saga is active, false otherwise.

trackingToken

TrackingToken trackingToken()

Returns the TrackingToken belonging to the EventMessage last processed by this instance, or null if this instance never handled an EventMessage, or if it received an EventMessage that doesn't carry a TrackingToken.

Returns:

the TrackingToken of the last processed EventMessage, if present.