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An example on how to customize an Event Bus in Akka. See article http://danielasfregola.com/2015/04/20/peer-to-many-communication-in-akka/
import akka.actor._
import akka.event.{LookupClassification, EventBus}
import akka.event.ActorEventBus
case class Book(title: String, authors: List[String])
class AuthorBookBus(author: String) extends EventBus
with LookupClassification
with ActorEventBus {
type Event = Book
type Classifier = Boolean
override def mapSize = 2
override def classify(book: Book) = book.authors.contains(author)
override protected def publish(book: Book, subscriber: Subscriber)= subscriber ! book
}
class BookPublisher(bus: AuthorBookBus) extends Actor {
def receive = {
case book: Book => {
println(s"Yeah! Publishing a new book: $book")
bus.publish(book)
}
}
}
class BookSubscriber extends Actor {
def receive = {
case book: Book => println(s"My name is ${self.path.name} and I have received a new book: $book")
}
}
object Main extends App {
implicit val system = ActorSystem("publisher-subscribers-example")
val author = "Author"
val authorBookBus = new AuthorBookBus(author)
val bookPublisher = system.actorOf(Props(new BookPublisher(authorBookBus)), name = "book-publisher")
val subscriber1 = system.actorOf(Props[BookSubscriber], name = "subscriber-1")
val subscriber2 = system.actorOf(Props[BookSubscriber], name = "subscriber-2")
authorBookBus.subscribe(subscriber1, true)
authorBookBus.subscribe(subscriber2, false)
bookPublisher ! Book(title = "A book title", authors = List(author, "Another Author"))
// Yeah! Publishing a new book: Book(A book title,List(Author, Another Author))
// My name is subscriber-1 and I have received a new book: Book(A book title,List(Author, Another Author))
bookPublisher ! Book(title = "Another book title", authors = List("Another Author"))
// Yeah! Publishing a new book: Book(Another book title,List(Another Author))
// My name is subscriber-2 and I have received a new book: Book(Another book title,List(Another Author))
}
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