server/io.spine.server.projection/Projection

Projection

public abstract class Projection<I, M extends EntityState, B extends ValidatingBuilder<M>> extends TransactionalEntity<I, S, B> implements EventPlayer, EventSubscriber, HasVersionColumn<I, S>, HasLifecycleColumns<I, S>

Projection holds a structural representation of data extracted from a stream of events.

The process of projecting the event stream into data we collect is performed by event subscribers for the events of interest. These event handlers are implemented in the classes extending this abstract class.

Event subscribers are invoked by a ProjectionRepository that manages instances of a stream projection class.

Parameters

<I>

the type of the IDs

<M>

the type of the state objects holding projection data

Inheritors

MirrorProjection

Constructors

Projection

protected void Projection()

Creates a new instance.

protected void Projection(I id)

Creates a new instance.

Inherited properties

lifecycleFlags

public volatile LifecycleFlags lifecycleFlags

The lifecycle flags of the entity.

version

public volatile Version version

The version of the entity.

Functions

builder

protected final B builder()

Obtains the instance of the state builder.

missingTxMessage

protected String missingTxMessage()

Provides error message text for the case of not having an active transaction when a state modification call is made.

modelClass

protected ProjectionClass<? extends Object> modelClass()

Obtains the model class.

play

public BatchDispatchOutcome play(Iterable<Event> events)

Plays the given events against the underlying entity.

thisClass

protected ProjectionClass<? extends Object> thisClass()

Obtains model class for this entity.

Inherited functions

afterInvoke

public void afterInvoke(HandlerMethod<? extends Object, ? extends Object, ? extends Object, ? extends Object> method)

A callback for a handler method invocation end.

public final Api at(Level logLevel)

Obtains a new fluent logging API at the given level.

beforeInvoke

public void beforeInvoke(HandlerMethod<? extends Object, ? extends Object, ? extends Object, ? extends Object> method)

A callback for a handler method invocation start.

changed

public final boolean changed()

Determines whether the state of this entity or its lifecycle flags have been modified since this entity instance creation.

checkEntityState

protected final List<ConstraintViolation> checkEntityState(S newState)

Verifies the new entity state and returns ConstraintViolations, if any.

checkNotArchived

protected void checkNotArchived()

Ensures that the entity is not marked as archived.

checkNotDeleted

protected void checkNotDeleted()

Ensures that the entity is not marked as deleted.

clearRecentHistory

protected void clearRecentHistory()

Clears recent history.

defaultState

protected final S defaultState()

Obtains the default state of the entity.

ensureAccessToState

protected void ensureAccessToState()

Ensures that the callee is allowed to access Entity's state() method.

equals

public boolean equals(Object o)

forTransactionOf

public static EventPlayer forTransactionOf(TransactionalEntity<? extends Object, ? extends Object, ? extends Object> entity)

Creates a transactional EventPlayer for the given entity.

getArchived

public boolean getArchived()

Obtains the value of archived flag.

getDeleted

public boolean getDeleted()

Obtains the value of deleted flag.

getLifecycleFlags

public final LifecycleFlags getLifecycleFlags()

Obtains the current state of the entity lifecycle flags.

getVersion

public Version getVersion()

Obtains the version of the entity.

hashCode

public int hashCode()

public I id()

Obtains the identifier of the entity.

idAsString

public String idAsString()

Obtains ID of the entity in the string form.

isActive

public boolean isActive()

Verifies if any of the lifecycle attributes is set.

isArchived

public final boolean isArchived()

Tests whether the entity is marked as archived.

isDeleted

public final boolean isDeleted()

Tests whether the entity is marked as deleted.

lifecycleFlags

public LifecycleFlags lifecycleFlags()

Obtains current lifecycle flags.

lifecycleFlagsChanged

public boolean lifecycleFlagsChanged()

Tells whether lifecycle flags of the entity changed since its initialization.

play

public DispatchOutcome play(Event event)

Plays the given event.

recentHistory

protected RecentHistory recentHistory()

Obtains recent history of events of this entity.

remember

protected void remember(Iterable<Event> events)

Adds events to the recent history.

setArchived

protected final void setArchived(boolean archived)

Sets archived} status flag to the passed value.

setDeleted

protected final void setDeleted(boolean deleted)

Sets deleted} status flag to the passed value.

setInitialState

protected final void setInitialState(S initialState, Version version)

Sets an initial state for the entity.

state

public final S state()

Obtains the state of the entity.

toString

public String toString()

protected Transaction<I, ? extends TransactionalEntity<I, S, B>, S, B> tx()

Obtains the transaction used for modifying the entity.

version

public Version version()

Obtains the version of the entity.

versionNumber

protected int versionNumber()

Obtains the version number of the entity.

whenModified

public Timestamp whenModified()

Obtains timestamp of the entity version.