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!per #15884 Make LevelDB an optional dependency

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Andrei Pozolotin 2015-03-06 11:58:51 -06:00
parent 1313fb736d
commit 5c5e07ec4e
13 changed files with 196 additions and 56 deletions
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57
akka-docs/rst/java/lambda-persistence.rst
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@ -48,6 +48,22 @@ Akka persistence is a separate jar file. Make sure that you have the following d
<version>@version@</version>
</dependency>
Akka persistence extension comes with few built-in persistence plugins, including
in-memory heap based journal, local file-system based snapshot-store and LevelDB based journal.
LevelDB based plugins will require the following additional dependency declaration::
<dependency>
<groupId>org.iq80.leveldb</groupId>
<artifactId>leveldb</artifactId>
<version>0.7</version>
</dependency>
<dependency>
<groupId>org.fusesource.leveldbjni</groupId>
<artifactId>leveldbjni-all</artifactId>
<version>1.7</version>
</dependency>
Architecture
============
@ -64,18 +80,19 @@ Architecture
case of sender and receiver JVM crashes.
* *Journal*: A journal stores the sequence of messages sent to a persistent actor. An application can control which messages
are journaled and which are received by the persistent actor without being journaled. The storage backend of a journal is
pluggable. The default journal storage plugin writes to the local filesystem, replicated journals are available as
`Community plugins`_.
are journaled and which are received by the persistent actor without being journaled. The storage backend of a journal is pluggable.
Persistence extension comes with a "leveldb" journal plugin, which writes to the local filesystem,
and replicated journals are available as `Community plugins`_.
* *Snapshot store*: A snapshot store persists snapshots of a persistent actor's or a view's internal state. Snapshots are
used for optimizing recovery times. The storage backend of a snapshot store is pluggable. The default snapshot
storage plugin writes to the local filesystem.
used for optimizing recovery times. The storage backend of a snapshot store is pluggable.
Persistence extension comes with a "local" snapshot storage plugin, which writes to the local filesystem,
and replicated snapshot stores are available as `Community plugins`_.
* *Event sourcing*. Based on the building blocks described above, Akka persistence provides abstractions for the
development of event sourced applications (see section :ref:`event-sourcing-java-lambda`)
.. _Community plugins: https://gist.github.com/krasserm/8612920#file-akka-persistence-plugins-md
.. _Community plugins: http://akka.io/community/
.. _event-sourcing-java-lambda:
@ -474,11 +491,25 @@ configuration key. The method can be overridden by implementation classes to ret
Storage plugins
===============
Storage backends for journals and snapshot stores are pluggable in Akka persistence. The default journal plugin
writes messages to LevelDB (see :ref:`local-leveldb-journal-java-lambda`). The default snapshot store plugin writes
snapshots as individual files to the local filesystem (see :ref:`local-snapshot-store-java-lambda`). Applications can
provide their own plugins by implementing a plugin API and activate them by configuration. Plugin development
requires the following imports:
Storage backends for journals and snapshot stores are pluggable in the Akka persistence extension.
Directory of persistence journal and snapshot store plugins is available at the Akka Community Projects page, see `Community plugins`_
Plugins can be selected either by "default", for all persistent actors and views,
or "individually", when persistent actor or view defines it's own set of plugins.
When persistent actor or view does NOT override ``journalPluginId`` and ``snapshotPluginId`` methods,
persistense extension will use "default" journal and snapshot-store plugins configured in the ``reference.conf``::
akka.persistence.journal.plugin = ""
akka.persistence.snapshot-store.plugin = ""
However, these entires are provided as empty "", and require explicit user configuration via override in the user ``application.conf``.
For an example of journal plugin which writes messages to LevelDB see :ref:`local-leveldb-journal-java-lambda`.
For an example of snapshot store plugin which writes snapshots as individual files to the local filesystem see :ref:`local-snapshot-store-java-lambda`.
Applications can provide their own plugins by implementing a plugin API and activate them by configuration.
Plugin development requires the following imports:
.. includecode:: ../../../akka-samples/akka-sample-persistence-java-lambda/src/main/java/doc/LambdaPersistencePluginDocTest.java#plugin-imports
@ -530,7 +561,7 @@ Pre-packaged plugins
Local LevelDB journal
---------------------
The default journal plugin is ``akka.persistence.journal.leveldb`` which writes messages to a local LevelDB
LevelDB journal plugin config entry is ``akka.persistence.journal.leveldb`` and it writes messages to a local LevelDB
instance. The default location of the LevelDB files is a directory named ``journal`` in the current working
directory. This location can be changed by configuration where the specified path can be relative or absolute:
@ -579,7 +610,7 @@ i.e. only the first injection is used.
Local snapshot store
--------------------
The default snapshot store plugin is ``akka.persistence.snapshot-store.local``. It writes snapshot files to
Local snapshot store plugin config entry is ``akka.persistence.snapshot-store.local`` and it writes snapshot files to
the local filesystem. The default storage location is a directory named ``snapshots`` in the current working
directory. This can be changed by configuration where the specified path can be relative or absolute: