io.spine.server.projection

Class Projection<I,M extends io.spine.base.EntityState,B extends io.spine.protobuf.ValidatingBuilder<M>>

java.lang.Object

io.spine.server.entity.AbstractEntity<I,S>

io.spine.server.entity.TransactionalEntity<I,M,B>

io.spine.server.projection.Projection<I,M,B>

Type Parameters:

I - the type of the IDs

M - the type of the state objects holding projection data

All Implemented Interfaces:

Entity<I,M>, HasLifecycleColumns<I,M>, HasVersionColumn<I,M>, WithLifecycle, EventReceiver, EventSubscriber, HandlerLifecycle

public abstract class Projection<I,M extends io.spine.base.EntityState,B extends io.spine.protobuf.ValidatingBuilder<M>>
extends TransactionalEntity<I,M,B>
implements EventSubscriber, HasVersionColumn<I,M>, HasLifecycleColumns<I,M>

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.

Nested Class Summary

Nested classes/interfaces inherited from interface io.spine.server.entity.Entity

Entity.GenericParameter

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Projection() Creates a new instance.
protected	Projection(I id) Creates a new instance.

Method Summary

Modifier and Type	Method and Description
protected B	builder() Obtains the instance of the state builder.
protected java.lang.String	missingTxMessage() Provides error message text for the case of not having an active transaction when a state modification call is made.
io.spine.server.dispatch.BatchDispatchOutcome	play(java.lang.Iterable<io.spine.core.Event> events)
protected ProjectionClass<?>	thisClass() Obtains model class for this entity.

Methods inherited from class io.spine.server.entity.TransactionalEntity

clearRecentHistory, getLifecycleFlags, recentHistory, remember, setArchived, setDeleted, setInitialState, tx

Methods inherited from class io.spine.server.entity.AbstractEntity

afterInvoke, at, beforeInvoke, checkEntityState, checkNotArchived, checkNotDeleted, defaultState, equals, hashCode, id, idAsString, isArchived, isDeleted, lifecycleFlagsChanged, state, toString, version, versionNumber, whenModified

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface io.spine.server.entity.WithLifecycle

isActive, lifecycleFlags

Constructor Detail

Projection

protected Projection()

Creates a new instance.

Projection

protected Projection(I id)

Creates a new instance.

Parameters:

id - the ID for the new instance

Method Detail

thisClass

protected ProjectionClass<?> thisClass()

Description copied from class: AbstractEntity

Obtains model class for this entity.

Overrides:

thisClass in class AbstractEntity<I,M extends io.spine.base.EntityState>

builder

protected final B builder()

Obtains the instance of the state builder.

This method must be called only from within an active transaction.

Overridden to expose the method to the package.

Overrides:

builder in class TransactionalEntity<I,M extends io.spine.base.EntityState,B extends io.spine.protobuf.ValidatingBuilder<M>>

Returns:

the instance of the new state builder

missingTxMessage

protected java.lang.String missingTxMessage()

Description copied from class: TransactionalEntity

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

Overrides:

missingTxMessage in class TransactionalEntity<I,M extends io.spine.base.EntityState,B extends io.spine.protobuf.ValidatingBuilder<M>>

play

public io.spine.server.dispatch.BatchDispatchOutcome play(java.lang.Iterable<io.spine.core.Event> events)