This subproject provides a home to modules contributed by external developers which may or may not move into the officially supported code base over time. The conditions under which this transition can occur include:
- there must be enough interest in the module to warrant inclusion in the standard distribution,
- the module must be actively maintained and
- code quality must be good enough to allow efficient maintenance by the Akka core development team
If a contributions turns out to not “take off” it may be removed again at a later time.
A module in this subproject doesn't have to obey the rule of staying binary compatible between minor releases. Breaking API changes may be introduced in minor releases without notice as we refine and simplify based on your feedback. A module may be dropped in any release without prior deprecation. The Typesafe subscription does not cover support for these modules.
The Current List of Modules
- Reliable Proxy Pattern
- Throttling Actor Messages
- Java Logging (JUL)
- Mailbox with Explicit Acknowledgement
- Cluster Singleton
- Cluster Sharding
- Distributed Publish Subscribe in Cluster
- Cluster Client
- Aggregator Pattern
Suggested Way of Using these Contributions
Since the Akka team does not restrict updates to this subproject even during otherwise binary compatible releases, and modules may be removed without deprecation, it is suggested to copy the source files into your own code base, changing the package name. This way you can choose when to update or which fixes to include (to keep binary compatibility if needed) and later releases of Akka do not potentially break your application.
Suggested Format of Contributions
Each contribution should be a self-contained unit, consisting of one source
file or one exclusively used package, without dependencies to other modules in
this subproject; it may depend on everything else in the Akka distribution,
though. This ensures that contributions may be moved into the standard
distribution individually. The module shall be within a subpackage of
Each module must be accompanied by a test suite which verifies that the
provided features work, possibly complemented by integration and unit tests.
The tests should follow the Developer Guidelines and go into the
src/test/java directories (with package name matching
the module which is being tested). As an example, if the module were called
akka.contrib.pattern.ReliableProxy, then the test suite should be called
Each module must also have proper documentation in reStructured Text format.
The documentation should be a single
<module>.rst file in the
akka-contrib/docs directory, including a link from
index.rst (this file).