Packages

  • package root
    Definition Classes
    root
  • package com
    Definition Classes
    root
  • package lightbend
    Definition Classes
    com
  • package lagom
    Definition Classes
    lightbend
  • package scaladsl
    Definition Classes
    lagom
  • package persistence
    Definition Classes
    scaladsl
  • abstract class PersistentEntity extends AnyRef

    A PersistentEntity has a stable entity identifier, with which it can be accessed from anywhere in the cluster.

    A PersistentEntity has a stable entity identifier, with which it can be accessed from anywhere in the cluster. It is run by an actor and the state is persistent using event sourcing.

    initialState and behavior are abstract methods that your concrete subclass must implement. The behavior is defined as a set of actions given a state. The actions are functions to process incoming commands and persisted events.

    The PersistentEntity receives commands of type Command that can be validated before persisting state changes as events of type Event. The functions that process incoming commands are registered in the Actions using onCommand of the Actions.

    A command may also be read-only and only perform some side-effect, such as replying to the request. Such command handlers are registered using onReadOnlyCommand of the Actions. Replies are sent with the reply method of the context that is passed to the command handler function.

    A command handler returns a Persist directive that defines what event or events, if any, to persist. Use the thenPersist, thenPersistAll or done methods of the context that is passed to the command handler function to create the Persist directive.

    When an event has been persisted successfully the state of type State is updated by applying the event to the current state. The functions for updating the state are registered with the onEvent method of the Actions. The event handler returns the new state. The state must be immutable, so you return a new instance of the state. Current state is passed as parameter to the event handler. The same event handlers are also used when the entity is started up to recover its state from the stored events.

    After persisting an event, external side effects can be performed in the afterPersist function that can be defined when creating the Persist directive. A typical side effect is to reply to the request to confirm that it was performed successfully. Replies are sent with the reply method of the context that is passed to the command handler function.

    The command handlers may emit zero, one or many events. When many events are emitted, they are stored atomically and in the same order they were emitted. Only after persisting all the events external side effects will be performed.

    The event handlers are typically only updating the state, but they may also change the behavior of the entity in the sense that new functions for processing commands and events may be defined for a given state. This is useful when implementing finite state machine (FSM) like entities.

    When the entity is started the state is recovered by replaying stored events. To reduce this recovery time the entity may start the recovery from a snapshot of the state and then only replaying the events that were stored after the snapshot. Such snapshots are automatically saved after a configured number of persisted events.

    Definition Classes
    persistence
  • Actions
  • Command
  • CommandContext
  • Event
  • Persist
  • ReadOnlyCommandContext
  • State

trait Persist extends AnyRef

A command handler returns a Persist directive that defines what event or events, if any, to persist. Use the thenPersist, thenPersistAll or done methods of the context that is passed to the command handler function to create the Persist directive.

Source
PersistentEntity.scala
Linear Supertypes
AnyRef, Any
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Inherited
  1. Persist
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from Persist to any2stringadd[Persist] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Persist, B)
    Implicit
    This member is added by an implicit conversion from Persist to ArrowAssoc[Persist] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  8. def ensuring(cond: (Persist) ⇒ Boolean, msg: ⇒ Any): Persist
    Implicit
    This member is added by an implicit conversion from Persist to Ensuring[Persist] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  9. def ensuring(cond: (Persist) ⇒ Boolean): Persist
    Implicit
    This member is added by an implicit conversion from Persist to Ensuring[Persist] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: Boolean, msg: ⇒ Any): Persist
    Implicit
    This member is added by an implicit conversion from Persist to Ensuring[Persist] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean): Persist
    Implicit
    This member is added by an implicit conversion from Persist to Ensuring[Persist] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  13. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  14. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  15. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from Persist to StringFormat[Persist] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  16. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  17. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  19. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  20. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  21. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  22. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  23. def toString(): String
    Definition Classes
    AnyRef → Any
  24. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  25. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  26. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  27. def →[B](y: B): (Persist, B)
    Implicit
    This member is added by an implicit conversion from Persist to ArrowAssoc[Persist] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from Persist to any2stringadd[Persist]

Inherited by implicit conversion StringFormat from Persist to StringFormat[Persist]

Inherited by implicit conversion Ensuring from Persist to Ensuring[Persist]

Inherited by implicit conversion ArrowAssoc from Persist to ArrowAssoc[Persist]

Ungrouped