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Merge pull request #18421 from akka/wip-17139-clarify-AtLeastOnceDelivery-patriknw

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=per #17139 Clarify AtLeastOnceDelivery persistent state
This commit is contained in:
Patrik Nordwall 2015-09-09 19:03:45 +02:00
commit d76cf34487
3 changed files with 45 additions and 6 deletions
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17
akka-docs/rst/java/lambda-persistence.rst
View file

@ -557,6 +557,12 @@ To send messages with at-least-once delivery semantics to destinations you can e
class instead of ``AbstractPersistentActor`` on the sending side. It takes care of re-sending messages when they
have not been confirmed within a configurable timeout.
The state of the sending actor, including which messages that have been sent and still not been
confirmed by the recepient, must be persistent so that it can survive a crash of the sending actor
or JVM. The ``AbstractPersistentActorWithAtLeastOnceDelivery`` class does not persist anything by itself.
It is your responsibility to persist the intent that a message is sent and that a confirmation has been
received.
.. note::
At-least-once delivery implies that original message send order is not always preserved
@ -582,8 +588,15 @@ when the destination has replied with a confirmation message.
Relationship between deliver and confirmDelivery
------------------------------------------------
To send messages to the destination path, use the ``deliver`` method. If the persistent actor is not currently recovering,
this will send the message to the destination actor. When recovering, messages will be buffered until they have been confirmed using ``confirmDelivery``.
To send messages to the destination path, use the ``deliver`` method after you have persisted the intent
to send the message.
The destination actor must send back a confirmation message. When the sending actor receives this
confirmation message you should persist the fact that the message was delivered successfully and then call
the ``confirmDelivery`` method.
If the persistent actor is not currently recovering, the ``deliver`` method will send the message to
the destination actor. When recovering, messages will be buffered until they have been confirmed using ``confirmDelivery``.
Once recovery has completed, if there are outstanding messages that have not been confirmed (during the message replay),
the persistent actor will resend these before sending any other messages.

17
akka-docs/rst/java/persistence.rst
View file

@ -560,6 +560,12 @@ To send messages with at-least-once delivery semantics to destinations you can e
class instead of ``UntypedPersistentActor`` on the sending side. It takes care of re-sending messages when they
have not been confirmed within a configurable timeout.
The state of the sending actor, including which messages that have been sent and still not been
confirmed by the recepient, must be persistent so that it can survive a crash of the sending actor
or JVM. The ``UntypedPersistentActorWithAtLeastOnceDelivery`` class does not persist anything by itself.
It is your responsibility to persist the intent that a message is sent and that a confirmation has been
received.
.. note::
At-least-once delivery implies that original message send order is not always preserved
@ -585,8 +591,15 @@ when the destination has replied with a confirmation message.
Relationship between deliver and confirmDelivery
------------------------------------------------
To send messages to the destination path, use the ``deliver`` method. If the persistent actor is not currently recovering,
this will send the message to the destination actor. When recovering, messages will be buffered until they have been confirmed using ``confirmDelivery``.
To send messages to the destination path, use the ``deliver`` method after you have persisted the intent
to send the message.
The destination actor must send back a confirmation message. When the sending actor receives this
confirmation message you should persist the fact that the message was delivered successfully and then call
the ``confirmDelivery`` method.
If the persistent actor is not currently recovering, the ``deliver`` method will send the message to
the destination actor. When recovering, messages will be buffered until they have been confirmed using ``confirmDelivery``.
Once recovery has completed, if there are outstanding messages that have not been confirmed (during the message replay),
the persistent actor will resend these before sending any other messages.