Mongo Journal for Akka Persistence

A replicated Akka Persistence journal backed by MongoDB Casbah.

Prerequisites

Akka version:	2.3.0-RC1 or higher
Mongo version:	2.4.8 or higher

Installation

Build and install the journal plugin to your local Ivy cache with sbt publishLocal (requires sbt 0.13). It can then be included as dependency:

libraryDependencies += "com.github.ddevore" %% "akka-persistence-mongo-casbah" % "0.3-SNAPSHOT"

Configuration

To activate the Mongo journal plugin, add the following line to your Akka application.conf:

akka.persistence.journal.plugin = "casbah-journal"

This will run the journal with its default settings. The default settings can be changed with the following configuration keys:

casbah-journal.mongo-url.

A comma-separated list of Mongo hosts. You can specify as many hosts as necessary, for example, connections to replica sets. Default value is mongodb://localhost:27017/store.messages. For more information on configuring the mongo-url see Connection String Uri Format.

The default write concern is WriteConcern.Safe. This will be configurable sometime in the future.

WriteConcern.Safe will handle Exceptions are raised for network issues, and server errors; waits on a server for the write operation.
To better understand MongoDB WriteConcern see Write Concern.

Status

All operations required by the Akka Persistence journal plugin API are supported.
Message writes are batched to optimize throughput.
When using channels, confirmation writes are batched to optimize throughput.
Deletes (marked & permanent) are batched to optimize throughput.
Sharding is not yet supported.
This should be considered experimental as Akka-Persistence is still changing and the underlying storage structure may change.

Performance