Your first Ivy java application

We are going to write a "Hello world translater" for an Ivy bus. The application will subscribe to all messages starting with "Hello", and re-emit them after translating "Hello" into "Bonjour". In addition, the application will quit when it receives any message containing exactly "Bye".

The code

import fr.dgac.ivy.* ;

class ivyTranslater implements IvyMessageListener {

  private Ivy bus;

  ivyTranslater() {
    // initialization
    bus = new Ivy("IvyTranslater","Hello le monde",null);
    bus.bindMsg("^Hello(.*)",this);
    bus.bindMsg("^Bye$",new IvyMessageListener() {
      // callback for "Bye" message
      public void receive(IvyClient client, String[] args) {System.exit(0);}
    });
    try {
       // starts the bus on the default domain or IVY_DOMAIN property
       bus.start(null);
    } catch (IvyException ie) {
      System.err.println("can't run the Ivy bus" + ie.getMessage());
    }
  }

  // callback associated to the "Hello" messages"
  public void receive(IvyClient client, String[] args) {
    bus.sendMsg("Bonjour"+((args.length>0)?args[0]:""));
  }

  public static void main(String args[]) { new ivyTranslater(); }
}

Compiling

On a Unix computer, you should be able to compile the application with the following command :

$ javac ivyTranslater.java $

Testing

We are going to test our application with Probe. In a terminal window, launch ivyTranslater:

$ java ivyTranslater

Then in another terminal window, launch Probe. You are then ready to start, Type "Hello Paul", and you should get "Bonjour Paul". Then Type "Bye", and your application should quit :

$ java fr.dgac.ivy.Probe '(.*)' you want to subscribe to (.*) broadcasting on 127.255.255.255:2010 IvyTranslater connected IvyTranslater subscribes to ^Bye$ IvyTranslater subscribes to ^Hello(.*) IvyTranslater sent 'Hello le monde' Hello Paul -> Sent to 1 peers IvyTranslater sent 'Bonjour Paul' Bye -> Sent to 1 peers IvyTranslater disconnected <Ctrl-D> $