akka/akka

Build highly concurrent, distributed, and resilient message-driven applications on the JVM

Akka

The Akka family of projects is managed by teams at Lightbend with help from the community.

We believe that writing correct concurrent & distributed, resilient and elastic applications is too hard. Most of the time it's because we are using the wrong tools and the wrong level of abstraction.

Akka is here to change that.

Using the Actor Model we raise the abstraction level and provide a better platform to build correct concurrent and scalable applications. This model is a perfect match for the principles laid out in the Reactive Manifesto.

For resilience, we adopt the "Let it crash" model which the telecom industry has used with great success to build applications that self-heal and systems that never stop.

Actors also provide the abstraction for transparent distribution and the basis for truly scalable and fault-tolerant applications.

Learn more at akka.io.

Reference Documentation

The reference documentation is available at doc.akka.io, for Scala and Java.

Current versions of all Akka libraries

The current versions of all Akka libraries are listed on the Akka Dependencies page. Releases of the Akka core libraries in this repository are listed on the GitHub releases page.

Community

You can join these groups and chats to discuss and ask Akka related questions:

• Forums: discuss.akka.io
• Issue tracker:

In addition to that, you may enjoy following:

• The news section of the page, which is updated whenever a new version is released
• The Akka Team Blog
• The Akka articles in the Lightbend Blog
• Questions tagged #akka on StackOverflow

Contributing

Contributions are very welcome!

If you see an issue that you'd like to see fixed, or want to shape out some ideas, the best way to make it happen is to help out by submitting a pull request implementing it. We welcome contributions from all, even you are not yet familiar with this project, We are happy to get you started, and will guide you through the process once you've submitted your PR.

Refer to the CONTRIBUTING.md file for more details about the workflow, and general hints on how to prepare your pull request. You can also ask for clarifications or guidance in GitHub issues directly, or in the akka/dev chat if a more real time communication would be of benefit.

License

Akka is licensed under the Business Source License 1.1, please see the Akka License FAQ.

Tests and documentation are under a separate license, see the LICENSE file in each documentation and test root directory for details.

akka's Issues

Fix problem with POM property aliases

Akka Actor Kernel
akka
${akka.groupId}
${akka.version}
2009
pom

0.5 se.scalablesolutions.akka 2.7.5

Create MongoDB backend

MongoDB is a very fast storage system with a higher semantic than a DHT. Seems to have a lot of momentum lateley, more than Cabinet/Tyrant e.g.

EventBasedThreadPoolDispatcher blocks messages for non-busy handlers.

I've found a bug in the EventBasedThreadPoolDispatcher and created a failing test:

http://github.com/sergiob/akka/blob/a6c8382440c96097c65cae39175257f9af3ef844/kernel/src/test/scala/EventBasedThreadPoolDispatcherTest.scala
(see internalTestMessagesDispatchedToDifferentHandlersAreExecutedConcurrently)

The bug prevents messages to un-busy actors to be processed if a busy
handler has more than one message into the queue: that is, a busy
handler with more than one queued message will block all messages to
other handlers.

Transaction Monad

Rip code from my Lift JTA monad stuff.

REST frontend to JMX stats

Integrate scala-stat

Validate all akka.conf configuration options

Validate as part of bootstrap that all Configgy akka.conf options are set to valid options.

HotSwap based on AspectWerkz runtime weaving

JSON serialization for Java

Integrate Jackson
Add config option for:

• Cassandra
• Messages

Integrate pcollections

http://code.google.com/p/pcollections/
To enable java collection interfaces for persistent structures.

Split up and reorganize docs/wiki

Make it easier to understand how the parts integrate and which are needed for what.
Add good overview.

Enhance startup script

Add start/stop etc.

Add statistics real-time graph based on Comet

Use Lift's FlotComet:
http://github.com/dpp/liftweb/blob/0ad6f4ca9c682c0934986311f89dec6c3ce00723/sites/flotDemo/src/main/scala/net/liftweb/flot_demo/web/comet/FlotCometExample.scala

Serialization of Actor: SBinary and Java serialization

Concurrent Actor mode should be configurable per-actor

JTA integration

Integrate with my Lift Transaction Monad lib.

Annotation for user boot class

@bootclass
Integrate Scannotation

Terracotta backend

Base Dataflow Concurrency lib on Akka Actors + make it optionally distributed

Fix problems with remote supervison and fire-forget

@transactionrequired as config element in declarative config

CLI (Command Line Interface)

Use some JMX command line tool?

Akka wont build...

Hey Jonas,

Akka wont build out of the box, it fails with the following error:

src/main/scala/collection/Vector.scala:300: warning: non variable type-argument T in type pattern is unchecked since it is eliminated by erasure
case vec: Vector[T] => {

/EventBasedThreadPoolDispatcher.scala:300: error: type mismatch;
found : java.util.Collection[$1] where type $1 <: java.util.concurrent.Callable[T]
required: java.util.Collection[java.util.concurrent.Callable[?]]
def invokeAll[T](callables: Collection[ <: Callable[T]]) = executor.invokeAll(callables)
^
/Users/timperrett/repositories/scala/akka/kernel/src/main/scala/reactor/EventBasedThreadPoolDispatcher.scala:301: error: type mismatch;
found : java.util.Collection[$2] where type $2 <: java.util.concurrent.Callable[T]
required: java.util.Collection[java.util.concurrent.Callable[?]]
def invokeAll[T](callables: Collection[ <: Callable[T]], l: Long, timeUnit: TimeUnit) = executor.invokeAll(callables, l, timeUnit)
^
/Users/timperrett/repositories/scala/akka/kernel/src/main/scala/reactor/EventBasedThreadPoolDispatcher.scala:302: error: type mismatch;
found : java.util.Collection[$3] where type $3 <: java.util.concurrent.Callable[T]
required: java.util.Collection[java.util.concurrent.Callable[?]]
def invokeAny[T](callables: Collection[ <: Callable[T]]) = executor.invokeAny(callables)
^
/Users/timperrett/repositories/scala/akka/kernel/src/main/scala/reactor/EventBasedThreadPoolDispatcher.scala:303: error: type mismatch;
found : java.util.Collection[$4] where type $4 <: java.util.concurrent.Callable[T]
required: java.util.Collection[java.util.concurrent.Callable[?]]
def invokeAny[T](callables: Collection[ <: Callable[T]], l: Long, timeUnit: TimeUnit) = executor.invokeAny(callables, l, timeUnit)
^
/Users/timperrett/repositories/scala/akka/kernel/src/main/scala/state/DataFlowVariable.scala:96: warning: abstract type T in type pattern is unchecked since it is eliminated by erasure
val future: Future[T] = out !! (Get, {case t: T => t})

JSON serialization for Scala

Integrate literatejson
Add config option for:

• Cassandra
• Messages

Create serialization protocol for Scala based on SBinary

Plus integrate with remoting package (Netty).

Support stand-alone Cassandra integration

Document Use-cases: When, How, What (in terms of modules) for which use-case

Fault tolerance Concurrency Throughput Scalability

Draw pictures

Library mode

1. As service layer. Use actors as services. Local or distributed.
2. As 1 plus: Add tx storage as a cache alongside rdbms
3. As 1 plus: Use tx storage as db
4. Deploy in Jetty using akkaservlet to expose REST services
5. Use tx storage only using (upcoming):

• Java: annotations
• Scala: for comp

Stand alone kernel mode

1. Use as REST kernel to expose services
2. Use JAX-RS web framework features to build full stack web app.

MessageQueue striping

Reduce lock contention on the MessageQueue.
Bench and verify first.

Batching of NIO messages

ZooKeeper based STM

Memcached backend

Remote component provisioning

OSGi enable kernel.

Base on Apache Karaf.

Add MBean for all config and monitoring and management

Should expose scala-stat stuff as well as management.

Sorting of columns in Cassandra (time/name) should be configurable per PersistentMap basis

Add STM based on Multiverse

Work with Peter Veentjer to support Multiverse STM.
http://code.google.com/p/multiverse/

This would mean STM for all state in an Actor or Active Object not just managed references.

Open issues:

• Distributed transactions
• Instrument scalac generated bytecode
• Hook up with persistence?

DOS startup script

Tokyo Cabinet backend

Bootstrap kernel

Use the Boot class to bootstrap kernel

Redis backend

Implement OrElse for STM

Integrate Cassandra storage-config.xml in Scala code and configurable from akka.conf

Add support for scala-jersey and scala-lift

Add support plus write samples.

Add performance/scalability/thoughput benchmark

Fix Cassandra call to get_columns_since

Cassandra get_columns_since gotcha
This makes sense once you think about it, but it doesn’t appear to show up anywhere in the doc. If you call get_columns_since on a column family that is not ordered by Time, the call succeeds but always returns zero rows. To get this working you’ll need a column defined like this

Support Avro as user serialization format for remoting and storage

Concurrent Actor mode should be configurable on per-actor-basis

Apache Camel integration

Allow Actors to function as Camel Endpoints.
Finalize Producer/Consumer/Enpoint.

New STM based on versioned boxes

Pure read and write only transactions never clash.
Speculative read transactions.
Retry upon clash.
History GC.

Spring integration

Create a Spring interceptor (AOP alliance interceptor) for active objects.
Support @Autowired through guiceyfruit-spring.
Support Spring XML config?