io.simplesource.saga.action.eventsourcing

Class EventSourcingSpec<A,D,K,C>

java.lang.Object

io.simplesource.saga.action.eventsourcing.EventSourcingSpec<A,D,K,C>

Type Parameters:

A - common representation form for all action commands (typically Json / GenericRecord for Avro)

D - intermediate decoded input type (that can easily be converted to both K and C)

K - aggregate key type

C - simple sourcing command type

public final class EventSourcingSpec<A,D,K,C>
extends Object

A value class with the information required to define an event sourcing action processor.

See Also:

CommandSpec

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	EventSourcingSpec.UndoFunction<A,K,C> The UndoFunction functional interface.

Field Summary

Fields

Modifier and Type	Field and Description
String	actionType The Action type.
String	aggregateName The Simple Sourcing aggregate name.
java.util.function.Function<D,C>	commandMapper The Command mapper maps the decoded input type to a Simple Sourcing command.
io.simplesource.kafka.api.CommandSerdes<K,C>	commandSerdes The Command serdes are required for the command request and response topics.
java.util.function.Function<A,io.simplesource.data.Result<Throwable,D>>	inputDecoder The Input decoder.
java.util.function.Function<D,K>	keyMapper The Key mapper maps the decoded input type to the aggregate key.
java.util.function.Function<D,io.simplesource.data.Sequence>	sequenceMapper The Sequence mapper maps the decoded input type to the last read aggregate sequence.
java.time.Duration	timeout The Timeout.
EventSourcingSpec.UndoFunction<A,K,C>	undoCommand The Undo command.

Constructor Summary

Constructors

Constructor and Description
EventSourcingSpec()

Method Summary

Methods inherited from class java.lang.Object

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

Field Detail

actionType

public final String actionType

The Action type. Each action processor must have a unique action type.

aggregateName

public final String aggregateName

The Simple Sourcing aggregate name.

inputDecoder

public final java.util.function.Function<A,io.simplesource.data.Result<Throwable,D>> inputDecoder

The Input decoder. This converts the common action command representation to an intermediate decoded type. The A type is common across all action processors and action types. This enables working with a type that is specific to this action processor.

commandMapper

public final java.util.function.Function<D,C> commandMapper

The Command mapper maps the decoded input type to a Simple Sourcing command.

keyMapper

public final java.util.function.Function<D,K> keyMapper

The Key mapper maps the decoded input type to the aggregate key.

sequenceMapper

public final java.util.function.Function<D,io.simplesource.data.Sequence> sequenceMapper

The Sequence mapper maps the decoded input type to the last read aggregate sequence.

With Simple Sourcing, updates to aggregates are versioned with a sequence number. With sequence checking enabled, the client specifies the last read sequence number. When Simple Sourcing processes the command request, it verifies that the sequence number of the aggregate is the same as the one specified by the client. This ensures that the command is being applied to the latest version of the aggregate.

With sagas, there may be more than one operation on a given aggregate instance. The client must specify the correct sequence number for the action that is executed first. After that the saga coordinator keeps track of the sequence number of the most recent write to the aggregate instance within the saga. This enables an optimistic lock to be held for the duration of the saga.

undoCommand

public final EventSourcingSpec.UndoFunction<A,K,C> undoCommand

The Undo command. Note that in contrast to async action undos an undo command for a Simple Sourcing action must be of the same action type .

commandSerdes

public final io.simplesource.kafka.api.CommandSerdes<K,C> commandSerdes

The Command serdes are required for the command request and response topics.

timeout

public final java.time.Duration timeout

The Timeout. Currently not fully implemented - used to determine the maximum length of the join windows for waiting for responses from the command response topic

Constructor Detail

EventSourcingSpec

public EventSourcingSpec()