This actor is intended to be used on an external node that is not member of the cluster. It acts like a gateway for sending messages to actors somewhere in the cluster. From the initial contact points it will establish a connection to a ClusterReceptionist somewhere in the cluster. It will monitor the connection to the receptionist and establish a new connection if the link goes down. When looking for a new receptionist it uses fresh contact points retrieved from previous establishment, or periodically refreshed contacts, i.e. not necessarily the initial contact points.
You can send messages via the `ClusterClient` to any actor in the cluster that is registered in the ClusterReceptionist. Messages are wrapped in ClusterClient.Send, ClusterClient.SendToAll or ClusterClient.Publish.
1. ClusterClient.Send - The message will be delivered to one recipient with a matching path, if any such exists. If several entries match the path the message will be delivered to one random destination. The sender of the message can specify that local affinity is preferred, i.e. the message is sent to an actor in the same local actor system as the used receptionist actor, if any such exists, otherwise random to any other matching entry.
2. ClusterClient.SendToAll - The message will be delivered to all recipients with a matching path.
3. ClusterClient.Publish - The message will be delivered to all recipients Actors that have been registered as subscribers to to the named topic.
Use the factory method ClusterClient.Props to create the Akka.Actor.Props for the actor.
