I still need the full stacktrace

[INFO] [02/20/2012 16:05:34.400] [main] [ActorSystem(client)] REMOTE: RemoteServerStarted@akka://client@0.0.0.0:3100
[INFO] [02/20/2012 16:05:34.560] [main] [ActorSystem(client)] REMOTE: RemoteClientStarted@akka://server@127.0.0.1:3000
[WARN] [02/20/2012 16:05:34.589] [main] [ActorSystem(client)] REMOTE: RemoteClientWriteFailed@akka://server@127.0.0.1:3000: MessageClass[scala.Tuple3] Error[java.lang.NullPointerException:null
at akka.actor.ExtensionId$class.apply(Extension.scala:34)
at akka.serialization.SerializationExtension$.apply(SerializationExtension.scala:12)
at akka.actor.TypedActor$MethodCall$$anonfun$writeReplace$1.apply$mcVI$sp(TypedActor.scala:135)
at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:78)
at akka.actor.TypedActor$MethodCall.writeReplace(TypedActor.scala:132)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at java.io.ObjectStreamClass.invokeWriteReplace(ObjectStreamClass.java:1049)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1131)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)
at akka.serialization.JavaSerializer.toBinary(Serializer.scala:114)
at akka.remote.MessageSerializer$.serialize(MessageSerializer.scala:31)
at akka.remote.RemoteMarshallingOps$$anonfun$createRemoteMessageProtocolBuilder$1.apply(RemoteTransport.scala:267)
at akka.remote.RemoteMarshallingOps$$anonfun$createRemoteMessageProtocolBuilder$1.apply(RemoteTransport.scala:267)
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
at akka.remote.RemoteMarshallingOps$class.createRemoteMessageProtocolBuilder(RemoteTransport.scala:266)
at akka.remote.netty.NettyRemoteTransport.createRemoteMessageProtocolBuilder(NettyRemoteSupport.scala:29)
at akka.remote.netty.RemoteMessageEncoder.encode(NettyRemoteSupport.scala:200)
at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:61)
at org.jboss.netty.handler.execution.ExecutionHandler.handleDownstream(ExecutionHandler.java:165)
at org.jboss.netty.channel.Channels.write(Channels.java:605)
at org.jboss.netty.channel.Channels.write(Channels.java:572)
at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:245)
at akka.remote.netty.RemoteClient.send(Client.scala:75)
at akka.remote.netty.RemoteClient.send(Client.scala:62)
at akka.remote.netty.NettyRemoteTransport.send(NettyRemoteSupport.scala:136)
at akka.remote.RemoteActorRef.$bang(RemoteActorRefProvider.scala:247)
at akka.actor.TypedActor$TypedActorInvocationHandler.invoke(TypedActor.scala:359)
at $Proxy0.sayHello(Unknown Source)
at rta.Client.main(Client.java:25)
]
[INFO] [02/20/2012 16:05:34.594] [client-akka.actor.default-dispatcher-2] [ActorSystem(client)] REMOTE: RemoteClientShutdown@akka://server@127.0.0.1:3000
[ERROR] [02/20/2012 16:05:34.597] [client-3] [ActorSystem(client)] REMOTE: RemoteClientError@akka://server@127.0.0.1:3000: Error[java.lang.NullPointerException:null
at akka.actor.ExtensionId$class.apply(Extension.scala:34)
at akka.serialization.SerializationExtension$.apply(SerializationExtension.scala:12)
at akka.actor.TypedActor$MethodCall$$anonfun$writeReplace$1.apply$mcVI$sp(TypedActor.scala:135)
at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:78)
at akka.actor.TypedActor$MethodCall.writeReplace(TypedActor.scala:132)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at java.io.ObjectStreamClass.invokeWriteReplace(ObjectStreamClass.java:1049)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1131)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:346)
at akka.serialization.JavaSerializer.toBinary(Serializer.scala:114)
at akka.remote.MessageSerializer$.serialize(MessageSerializer.scala:31)
at akka.remote.RemoteMarshallingOps$$anonfun$createRemoteMessageProtocolBuilder$1.apply(RemoteTransport.scala:267)
at akka.remote.RemoteMarshallingOps$$anonfun$createRemoteMessageProtocolBuilder$1.apply(RemoteTransport.scala:267)
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:57)
at akka.remote.RemoteMarshallingOps$class.createRemoteMessageProtocolBuilder(RemoteTransport.scala:266)
at akka.remote.netty.NettyRemoteTransport.createRemoteMessageProtocolBuilder(NettyRemoteSupport.scala:29)
at akka.remote.netty.RemoteMessageEncoder.encode(NettyRemoteSupport.scala:200)
at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:61)
at org.jboss.netty.handler.execution.ExecutionHandler.handleDownstream(ExecutionHandler.java:165)
at org.jboss.netty.channel.Channels.write(Channels.java:605)
at org.jboss.netty.channel.Channels.write(Channels.java:572)
at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:245)
at akka.remote.netty.RemoteClient.send(Client.scala:75)
at akka.remote.netty.RemoteClient.send(Client.scala:62)
at akka.remote.netty.NettyRemoteTransport.send(NettyRemoteSupport.scala:136)
at akka.remote.RemoteActorRef.$bang(RemoteActorRefProvider.scala:247)
at akka.actor.TypedActor$TypedActorInvocationHandler.invoke(TypedActor.scala:359)
at $Proxy0.sayHello(Unknown Source)
at rta.Client.main(Client.java:25)
]

Check latest master.

The client side NPE gone, but the server don't recognize the message

[INFO] [02/20/2012 19:53:01.958] [main] [ActorSystem(server)] REMOTE: RemoteServerStarted@akka://server@0.0.0.0:3000
hello from server
[INFO] [02/20/2012 19:53:08.282] [server-7] [ActorSystem(server)] REMOTE: RemoteClientStarted@akka://client@0.0.0.0:3100
[ERROR] [02/20/2012 19:53:08.418] [server-3] [NettyRemoteTransport(null)] dropping message MethodCall(public abstract void rta.service.HelloService.sayHello(java.lang.String),[Ljava.lang.Object;@6b46a226) for non-local recipient akka://server@127.0.0.1:3000/user/hello-service

I've pushed a new commit to Akka master that expands on the logging output in this case.
Please run your example against that. Also, make sure you have everything correctly set up and that the type actor path is as you expect.

Updating tickets (#1847, #1828, #1833, #1843, #1845, #1823, #1824, #1836, #1838, #1842, #1844, #1846)

[ERROR] [02/21/2012 09:11:36.832] [server-3] [NettyRemoteTransport(null)] dropping message MethodCall(public abstract void rta.service.HelloService.sayHello(java.lang.String),[Ljava.lang.Object;@594fb035) for non-local recipient akka://server@127.0.0.1:3000/user/hello-service at akka://server@0.0.0.0:3000 local is akka://server@0.0.0.0:3000

the server bind to 0.0.0.0:3000, client connect to server use 127.0.0.1:3000 treated as "non-local recipient "

Hi Jarod, we do not do a DNS lookup for every inbound message as that would be horribly inefficient.
If you use the same hostname to bind to and to connect to, does it work then?

Yes, it works.

Great, thanks!