Gamlor

This information here is allready quite outdated. With the current Akka 2.0 master snapshot some issues are gone, while new pitfalls introduced. I will update / create a new post when Akka 2.0 is close to the final release.

Akka 2.0 is available as a preview version. Here’s a short guide how to get it to run on Android. This pretty much work in progress. Maybe someone else has even has a better strategy. Let me know if that’s the case=). Also I didn’t do much with Akka 2.0 on Android yet, so maybe there are major issues yet to discover =).

Let's master this Akka-beast, little Android =)

In general I just assume that you have a working Scala build and know how to include new Scala libraries. And I also assume that you are using Proguard to shrink the jar file. I use a build based on this. In case you are having trouble, just ask for help =).

First add the Akka 2.0 M3 jar-file to the project (The M2 bits won’t work). Make sure that it is in your directories of libraries which are compacted by Proguard. Unfortunately you will get tons of warnings by Proguard about classes which couldn’t be found, because they are not part of the Android platform. These are three categories of classes which are not available:

• ‘ akka.util.JMX’: There is no JMX on Android.
• ‘sun.misc.Unsafe’: Well at first sight Android doesn’t have this implementation-detail class. Luckily it actually does have it (at least in newer versions), but it’s only available at runtime. The jars which you compile against do not have this class.
• ‘org.omg.CORBA’-stuff. The Akka library has a UUID implementation which implements some interfaces from CORBA.

So it is time for some Proguard trickery to get rid of warnings.

Bye Bye JMX

Well there is definitely no JMX on Android. So I just excluded the JMX stuff from Akka:

## No JMX for Android
-dontwarn akka.util.JMX*

Ignoring ‘sun.misc.Unsafe’ Warnings

The next step is to configure Proguard to ignore the ‘sun.misc.Unsafe’ warnings. It is there on the device (If not, please tell me).

## Unsafe is there at runtime
-dontwarn sun.misc.Unsafe
-keep class sun.misc.Unsafe{
    *;
}

Fixing the CORBA Stuff

## UUID helpers are not used
-dontwarn com.eaio.uuid.**

Remove the FSM Forward Reference

The core Akka library contains a forward reference to its finite state machine (FSM) implementation. In a usual class loader environment this doesn’t matter, since classes are lazily loaded. However Proguard is going to bitch about it. So in case you are not using the FSM library remove that reference with Proguard:

## No Finate State Machines Support needed
-dontwarn akka.actor.FSM

Keep Important Classes

Also we need to keep some classes which are loaded at runtime. Maybe there are more required for some features, just watch for class loader errors. These are the ones you need for sure:

## Stuff referenced at runtime
-keep public class akka.actor.LocalActorRefProvider {
   public <init>(...);
}
-keep class akka.event.Logging*
-keep class akka.event.Logging$LogExt{
    *;
}

Work Around the Reference Configuration Issue?

I’m not sure what exactly the issue is here and probably I’m doing something wrong. At least with my setup Akka cannot find its internal reference.conf resource file. Looks like resources are only loaded from the *.apk file? Anyway, for now I just copied the reference.conf file from the Akka source code to my project (Or do it with a build task). Then everything runs.

Conclusion

Yes, it is a little hairy to get Akka 2.0 to run on Android. I certainly will work a little more on it. And in case it gets too bad I’ll do a shallow fork of Akka .