Sending Email with Java and Akka actors

Rajith DelanthaOctober 2nd, 2013Last Updated: October 3rd, 2013

0 62 1 minute read

Akka is a concurrent framework written by Scala.

Here I demonstrate sample application to send emails with Akka and implemented in Java.

Reasons I decided to use Akka framework other than concurrency.

Built-in configurable supervisor strategy to monitor child workers and decide what policy applies when there is an exception.
Can reschedule delivery when application throwing some specific exception.
Use of actor routers and allow them to use actor connection pool.

Here is how to create supervision strategy.

class EmailServiceActor extends UntypedActor {  
   private static SupervisorStrategy strategy =  
       new OneForOneStrategy(10, Duration.create("1 minute"),  
           new Function<Throwable, Directive>() {  
             @Override 
             public Directive apply(Throwable t) {  
               if (t instanceof MessagingException) {  
                 return resume();  
               } else if (t instanceof Exception) {  
                 return stop();  
               } else {  
                 return escalate();  
               }  
             }  
           });  
   @Override 
   public void onReceive(Object message) {  
     getContext().actorOf(new Props(EmailServiceWorker.class)).tell(message, self());  
   }  
   @Override 
   public SupervisorStrategy supervisorStrategy() {  
     return strategy;  
   }  
 }

Here is how child worker create

class EmailServiceWorker extends UntypedActor {  
   @Override 
   public void onReceive(Object message) {  
     try {  
       EmailService emailService = new EmailService();  
       emailService.sendEmail();  
     } catch (IOException e) {  
       e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.  
     } catch (MessagingException e) {  
       e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.  
     }  
   }  
   @Override 
   public void preStart() {  
 //    getContext().system().scheduler().scheduleOnce(Duration.create(5, TimeUnit.SECONDS), self(), "emailWorker", getContext().system().dispatcher(), null);  
   }  
   @Override 
   public void postStop() {  
   }  
 }