shkr / actors

Springboard and Notes for --- Akka Actors

Actors

A collection of actor-systems defined on akka by typesafe.

API Documentation

PreStart

> sbt clean

> sbt compile

Receive

actors.basic.typed : Akka Typed

---

• An actor system (name = sanskaar) is setup, then the driver thread sends a message of type Pranam to the system decorated with Props using the “ask” pattern (represented by the ? operator)

> sbt "runMain org.shkr.actors.basic.typed.StaticActor"
 

basic.cluster.ClusterListener : Akka Cluster w/ Remote Actors

---

• INTRODUCTION An akka Cluster provides a fault-tolerant decentralized peer-to-peer based cluster membership service with no single point of failure or single point of bottleneck. It does this using gossip protocols and an automatic failure detector.
• An actor system is linked to (name = "ClusterSystem") and the main method takes as input port number, then starts a Cluster Listener Remote Actor on that port and joins itself as member of the Cluster whose seed nodes are listed as :

        "akka.tcp://[email protected]:2551"
        ] ```
  in the [reference.conf](https://github.com/shkr/actors/tree/master/src/main/scala/org/shkr/actors/basic/cluster/conf/reference.conf) file;      
  

> sbt "runMain org.shkr.actors.basic.cluster.ClusterListener 2551"  
 # This creates a ClusterListener Remote actor which registers itself as the first seed node of the Akka Cluster

cluster.transformation.{Frontend, Backend} : Modified Worker Dial-in Example

---

> sbt "runMain org.shkr.actors.basic.cluster.transformation.Frontend 2552 1" 
 # This creates a Frontend Remote actor; The main method also schedules a TransformationJob
   The ActorSystem on this node for each 2 second interval sends a Job to the Frontend Actors on this node
   in RoundRobin
> sbt "runMain org.shkr.actors.basic.cluster.transformation.Backend 2553 2"  
 # This creates a two Backend Remote actor which registers itself and listens to MemberUp events;
   In addition it informs the TransformationFrontend that it has registered itself, and does the
   any TransformationJob sent to it;

play.diningphilosophers : A Play of the Dining Philisophers

---

• An actor system is linked to (name = "DiningPhilisophers") and using a LocalActorRefProvider, we enact the Dining Philosophers.
• The actor system is configured inside the Configuration object which specifies the thinkingTime, eatingTime and the playTime

> sbt "runMain org.shkr.actors.play.diningphilosophers.Stage"
> sbt "runMain org.shkr.actors.play.diningphilosophers.Stage 8 4"

actors.persistence : Akka Persistence

---

• Ledger Example
• An actor system is created, and a Ledger Actor is intantiated to which some random transactions is sent. At the end of which we save a snapshot and print the current-time state of the Ledger
• The persistence plugin is configured to use Cassandra. The LevelDB and Local FileSystem which is available as part of akka-persistence can also be used. In order to do that Configuration has to be modified.

> sbt "runMain org.shkr.actors.persistence.Ledger Sonia"