Lesson 3: Actor’s address and PID.
In the previous lesson, we looked at the diagram where UserActor() sends a message IncrementPlayCount() to the actor MoviePlayCounterActor(). But as you can see, the actor MoviePlayCounterActor() is not a child actor UserActor() so we will not have a direct link to the actor MoviePlayCounterActor(). So what should we do in this case?
I want to remind you that in the Proto.Actor platform, the reference to another actor is PID. PID, in turn, is an abbreviation for process ID, i.e., it is a unique process identifier in the actor system.
The PID consists of a combination of an address and an ID. The address is the address of the host where the actor is hosted. for a remote host, it can be the IP address of the machine where the actor instance is hosted. The ID is a unique identifier of the actor on this host. It consists of a unique number and the name of the actor written in the format.
$"{system.ProcessRegistry.NextId()}/{name}"
Thus, knowing the address and ID of the interested actor, we can create its PID manually. It is done in the following way.
var moviePlayCounterActorPid = new PID(system.ProcessRegistry.Address, "$1/MoviePlayCounterActor");
Now we can use the resulting PID’s to send messages to our actor. Regardless of where it is deployed and whether our actor is a child.
