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

abstract class CommandContext[R] extends ReadOnlyCommandContext[R]

The context that is used by command handler function. Events are persisted with the context and replies are sent with the context.

R

the reply type of the command

Source
PersistentEntity.scala
Linear Supertypes
ReadOnlyCommandContext[R], AnyRef, Any
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. CommandContext
  2. ReadOnlyCommandContext
  3. AnyRef
  4. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new CommandContext()

Abstract Value Members

  1. abstract def commandFailed(cause: Throwable): Unit

    Reply with a negative acknowledgment.

    Reply with a negative acknowledgment.

    Definition Classes
    ReadOnlyCommandContext
  2. abstract def reply(msg: R): Unit

    Send reply to a command.

    Send reply to a command. The type R must be the reply type defined by the command.

    Definition Classes
    ReadOnlyCommandContext

Concrete 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 CommandContext[R] to any2stringadd[CommandContext[R]] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (CommandContext[R], B)
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to ArrowAssoc[CommandContext[R]] 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 done[B <: Event]: Persist

    A command handler may return this Persist directive to define that no events are to be persisted.

  9. def ensuring(cond: (CommandContext[R]) ⇒ Boolean, msg: ⇒ Any): CommandContext[R]
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to Ensuring[CommandContext[R]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: (CommandContext[R]) ⇒ Boolean): CommandContext[R]
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to Ensuring[CommandContext[R]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean, msg: ⇒ Any): CommandContext[R]
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to Ensuring[CommandContext[R]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean): CommandContext[R]
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to Ensuring[CommandContext[R]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  15. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  16. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to StringFormat[CommandContext[R]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  17. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  19. def invalidCommand(message: String): Unit

    Reply with a negative acknowledgment using the standard InvalidCommandException.

    Reply with a negative acknowledgment using the standard InvalidCommandException.

    Definition Classes
    ReadOnlyCommandContext
  20. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  21. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  22. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  23. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  24. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  25. def thenPersist[B <: Event](event: B)(afterPersist: (B) ⇒ Unit = (_: B) => ()): Persist

    A command handler may return this Persist directive to define that one event is to be persisted.

    A command handler may return this Persist directive to define that one event is to be persisted. External side effects can be performed after successful persist in the afterPersist function.

  26. def thenPersistAll(events: Event*)(afterPersist: () ⇒ Unit = () => ()): Persist

    A command handler may return this Persist directive to define that several events are to be persisted.

    A command handler may return this Persist directive to define that several events are to be persisted. External side effects can be performed after successful persist in the afterPersist function. afterPersist is invoked once when all events have been persisted successfully. Events will be persisted atomically and in the same order as they are passed here.

  27. def toString(): String
    Definition Classes
    AnyRef → Any
  28. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  29. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  30. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  31. def →[B](y: B): (CommandContext[R], B)
    Implicit
    This member is added by an implicit conversion from CommandContext[R] to ArrowAssoc[CommandContext[R]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from ReadOnlyCommandContext[R]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from CommandContext[R] to any2stringadd[CommandContext[R]]

Inherited by implicit conversion StringFormat from CommandContext[R] to StringFormat[CommandContext[R]]

Inherited by implicit conversion Ensuring from CommandContext[R] to Ensuring[CommandContext[R]]

Inherited by implicit conversion ArrowAssoc from CommandContext[R] to ArrowAssoc[CommandContext[R]]

Ungrouped