Hi Luis, On Tue, May 20, 2014 at 2:58 AM, Luis Medina <lu4...@gmail.com> wrote:
> Thank you for the help Martynas. Got a couple of follow-up questions: > > >> Cluster singleton is always created on the oldest node in the cluster >> with a specified role if any. This implies that there could a resource >> bottleneck on the oldest node. > > > 1. Is there any way to define a different strategy that creates singletons > in a random node similar to how you can configure a different strategy for > the ShardCoordinator when allocating new shards? > This is not currently supported by a ClusterSingletonManager. Sharding solves this particular issue. > > 2. In distributed PubSub, when I publish a message from actor (a), will > subscribers who receive the message know that it came from actor (a)? Or is > this information lost? > Yes. The sender is still there and can be used as it is in clustering pubsub activator template<https://github.com/typesafehub/activator-akka-clustering/blob/master/src/main/scala/chat/ChatClient.scala#L27> . > > 3. If I subscribe a round-robin cluster-aware pool router to a particular > topic using cluster PubSub, will the round-robinness still hold for the > messages that are sent to it? > > I'm thinking this would probably look something like this in code: > > //configuration > akka.actor.deployment { > /master/worker { > router = round-robin-pool > > nr-of-instances = 10 > cluster { > enabled = on > } > } > } > > //code > ActorRef router = > getContext().actorOf(FromConfig.getInstance().props(Props.create(Worker.class)), > "worker"); > > ActorRef mediator = > DistributedPubSubExtension.get(getContext().system()).mediator(); > mediator.tell(new DistributedPubSubMediator.Subscribe("topic", router), > router); > Yes. This will work. Router has an ordinary Actor Path which can be used to subscribe to a topics in PubSub. > > 4. In the distributed PubSub documentation page ( > http://doc.akka.io/docs/akka/2.3.2/contrib/distributed-pub-sub.html#distributed-pub-sub) > at the bottom, they explain the different configurations for this feature. > a. What units of time can be specified for the "gossip-interval"? In the > example they use seconds but can you do milliseconds? > Yes. It can be specified in ms. However the smaller the value, the more traffic you are going to get in the cluster, especially in cases when there are lots of new/old subscriptions. > b. I'm a little unclear as to what "max-delta-elements" is used for. It > says that it's the max. number of elements to be transfered in one message > when the registry is synchronized. Where are these elements being moved > to/from? Also, what is the distinction between elements and message? > This is a setting for the pub-sub gossip protocol. In this case elements are subscriptions to some particular topic or path that Mediator actors keep track of. This data is exchanged between Mediator actors. > > 5. In distributed PubSub, if I were to publish a message to a topic that > has no subscribers, will the message simply get dropped since it couldn't > find anyone to send it to, or does it get queued somewhere until someone > subscribes to that topic? > Messages would simply be dropped. > > 6. Is it possible to use a ClusterClient together with distributed PubSub > to subscribe to a particular topic from an actor that is outside of the > cluster? > This is not currently supported. As a side node, it could be used the other way around. In fact ClusterReceptionist that ClusterClient talks to, is itself built on PubSub. > > They are even more loosely coupled, the messages are sent to the defined >> path, i.e. using ActorSelection. There is no identification process. That >> means that the target actors can be started after the router, or stopped >> and started again, and still participate in the router. Messages will be >> delivered to deadLetters when the actor of the target path does not exist. > > > Good to know! Thanks Patrik. > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Martynas Mickevičius Typesafe <http://typesafe.com/> – Reactive<http://www.reactivemanifesto.org/>Apps on the JVM -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. 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