An actor system that is not part of the cluster can communicate with actors somewhere in the cluster via this ClusterClientClusterClient. The client can of course be part of another cluster. It only needs to know the location of one (or more) nodes to use as initial contact points. It will establish a connection to a ClusterReceptionistClusterReceptionist 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.
The receptionist is supposed to be started on all nodes, or all nodes with specified role, in the cluster. The receptionist can be started with the ClusterClientReceptionistClusterClientReceptionist extension or as an ordinary actor.
"com.typesafe.akka" %% "akka-cluster-tools" % "2.5.11"