Actor model of Akka 4 Akka

1. What's an Actor?

The Actor Model represents objects and their interactions, resembling

Human organizations and built upon the laws of physics.

is a object with identity

Has a behavior

Only interacts using asynchronous message passing

2. The Actor Trait

Type Receive = Partialfunction[any, Unit]

Trait Actor {

def receive:receive

...

}

The actor type describes the behavior of an actor, its response to

Messages.

3.A Simple Actor

Class Counter extends Actor {

var count = 0

def receive = {

Case "INCR" = + count + = 1

}

}

This object does not exhibit stateful behavior does not show any status of the actor

4. Making It Stateful let it be stateful

Actors can send messages to addresses (ACTORREF) They know (actor can send messages to the actor it knows):

Class Counter extends Actor {

var count = 0

def receive = {

Case "INCR" = + count + = 1

Case ("Get", customer:actorref) = customer! Count

}

}

5.

How Messages is Sent

Trait Actor {

Implicit Val Self:actorref

def sender:actorref

...

}

Abstract class Actorref {

Def! (Msg:any) (Implicit sender:actorref = Actor.nosender): Unit

def tell (Msg:any, sender:actorref) = this.! (msg) (sender)

...

}

Sending a message from one actor to the other picks up the sender ' s

Address implicitly. Sender's address is automatically passed to receiver

6. Send a message using the sender method

Using the Sender

Class Counter extends Actor {

var count = 0

def receive = {

Case "INCR" = + count + = 1

Case "GET" = sender! Count

}

}

7. The actor context defines the become and Unbecome methods that can change the actor's behavior

The Actor ' s Context

The Actor type describes the behavior, the execution is do by its

Actorcontext.

Trait Actorcontext {

def become (behavior:receive, Discardold:boolean = True): Unit

Def unbecome (): Unit

...

}

Trait Actor {

Implicit Val Context:actorcontext

...

}

8. Change actor's behavior

Changing an Actor ' s Behavior

Class Counter extends Actor {

def counter (n:int): Receive = {

Case "INCR" = context.become (Counter (n + 1))

Case "GET" = sender! N

}

def receive = counter (0)

}

9. Create actor and Storp methods using the Actorof method of the context stop actor

Creating and Stopping Actors

Trait Actorcontext {

def actorof (P:props, name:string): Actorref

def stop (a:actorref): Unit

...

}

Actors is created by Actors.

' Stop ' is often applied to ' self '.

10. Complete Example

Package Week5import Akka.actor.Actorimport Akka.actor.Propsclass Countermain extends actor {val counter = Context.actoro F (Props[counter], "Counter") Counter! "INCR" Counter! "INCR" Counter! "GET" def receive = {Case Count:int = println (S "Count is $count") Context.stop (self)}

Package Week5import Akka.actor.Actorclass Counter extends actor {var count = 0 def receive = {case "incr" = = Cou NT + = 1 case "Get" = sender! Count}}

Props[counter]-----Counter for the actor class defined below us

Counter----for the name of this new actor.

Once the actor receives the message, it can do the following

Upon reception of a message the actor can do any combination of the

Following:

Send messages Message

Create actors creating actor

Designate the behavior for the next message design the behavior logic after receiving the next messages

Akka 4 Akka Actor Model