Good use case for Akka [closed]

Question

I have heard lots of raving about Akka framework (Java/Scala service platform), but so far have not seen many actual examples of use cases it would be good for. So I would be interested in hearing about things developers have used it succesfully.

Only one limitation: please do not include case of writing a chat server. (why? since this has been overused as an example for lots of similar things)

Answer 1

We are using Akka in a large scale Telco project (unfortunately I can't disclose a lot of details). Akka actors are deployed and accessed remotely by a web application. In this way, we have a simplified RPC model based on Google protobuffer and we achieve parallelism using Akka Futures. So far, this model has worked brilliantly. One note: we are using the Java API.

Answer 2

We are using akka with its camel plugin to distribute our analysis and trending processing for twimpact.com. We have to process between 50 and 1000 messages per second. In addition to multi-node processing with camel it is also used to distribute work on a single processor to multiple workers for maximum performance. Works quite well, but requires some understanding of how to handle congestions.

Answer 3

We use Akka in spoken dialog systems (primetalk). Both internally and externally. In order to simultaneously run a lot of telephony channels on a single cluster node it is obviously necessary to have some multithreading framework. Akka works just perfect. We have previous nightmare with the java-concurrency. And with Akka it is just like a swing — it simply works. Robust and reliable. 24*7, non-stop.

Inside a channel we have real-time stream of events that are processed in parallel. In particular: - lengthy automatic speech recognition — is done with an actor; - audio output producer that mixes a few audio sources (including synthesized speech); - text-to-speech conversion is a separate set of actors shared between channels; - semantic and knowledge processing.

To make interconnections of complex signal processing we use SynapseGrid. It has the benefit of compile-time checking of the DataFlow in the complex actor systems.

Answer 4

Disclaimer: I am the PO for Akka

Besides offering a concurrency smorgasbord that is much simpler to reason about and to get correct (actors, agents, dataflow concurrency) and with concurrency control in the form of STM.

Here are some use-cases you might consider:

1. Transaction processing (online gaming, finance, statistics, betting, social media, telecom, ...)
   • scale up, scale out, fault-tolerance / HA
2. Service backend (any industry, any app)
   • service REST, SOAP, cometd etc
   • act as message hub / integration layer
   • scale up, scale out, fault-tolerance / HA
3. Snap-in concurrency/parallelism ( any app )
   • Correct
   • Simple to work with and understand
   • Just add the jars to your existing JVM project (use Scala, Java, Groovy or JRuby)
4. Batch processing ( any industry )
   • Camel integration to hook up with batch data sources
   • Actors divide and conquer the batch workloads
5. Communications hub ( telecom, web media, mobile media )
   • scale up, scale out, fault-tolerance / HA
6. Game server (online gaming, betting)
   • scale up, scale out, fault-tolerance / HA
7. BI/datamining/general purpose crunching
   • scale up, scale out, fault-tolerance / HA
8. insert other nice use cases here

Answer 5

I was trying out my hands on Akka (Java api). What I tried was to compare Akka's actor based concurrency model with that of plain Java concurrency model (java.util.concurrent classes).

The use case was a simple canonical map reduce implementation of character count. The dataset was a collection of randomly generated strings (400 chars in length), and calculate the number of vowels in them.

For Akka I used a BalancedDispatcher(for load balancing amongst threads) and RoundRobinRouter (to keep a limit on my function actors). For Java, I used simple fork join technique (implemented without any work stealing algorithm) that would fork map/reduce executions and join the results. Intermediate results were held in blocking queues to make even the joining as parallel as possible. Probably, if I am not wrong, that would mimic somehow the "mailbox" concept of Akka actors, where they receive messages.

Observation: Till medium loads (~50000 string input) the results were comparable, varying slightly in different iterations. However, as I increased my load to ~100000 it would hang the Java solution. I configured the Java solution with 20-30 threads under this condition and it failed in all iterations.

Increasing the load to 1000000, was fatal for Akka as well. I can share the code with anyone interested to have a cross check.

So for me, it seems Akka scales out better than traditional Java multithreaded solution. And probably the reason is the under the hood magic of Scala.

If I can model a problem domain as an event driven message passing one, I think Akka is a good choice for the JVM.

Test performed on: Java version:1.6 IDE: Eclipse 3.7 Windows Vista 32 bit. 3GB ram. Intel Core i5 processor, 2.5 GHz clock speed

Please note, the problem domain used for the test can be debated and I tried to be as much fair as my Java knowledge allowed :-)

Answer 6

If you abstract the chat server up a level, then you get the answer.

Akka provides a messaging system that is akin to Erlang's "let it crash" mentality.

So examples are things that need varying levels of durability and reliability of messaging:

• Chat server
• Network layer for an MMO
• Financial data pump
• Notification system for an iPhone/mobile/whatever app
• REST Server
• Maybe something akin to WebMachine (guess)

The nice things about Akka are the choices it affords for persistence, it's STM implementation, REST server and fault-tolerance.

Don't get annoyed by the example of a chat server, think of it as an example of a certain class of solution.

With all their excellent documentation, I feel like a gap is this exact question, use-cases and examples. Keeping in mind the examples are non-trivial.

(Written with only experience of watching videos and playing with the source, I have implemented nothing using akka.)