How to Code RMI

For RMI theory, see rmi-theory.html

Make a Remote Interface

This interface should extend java.rmi.Remote. Every function within it should throw java.rmi.RemoteException. The functions together should capture the behavior of the service you want to perform.

public interface RemoteInterface extends java.rmi.Remote{
public java.util.Date askTime() throws java.rmi.RemoteException;
public void tellTime(java.util.Date d) throws java.rmi.RemoteException;
}

Make a Remote Object

This object should extend java.rmi.server.UnicastRemoteObject and implement the interface you created above. Hopefully the functions you make here do the service you are trying to create.

public class RemoteObject extends java.rmi.server.UnicastRemoteObject
implements RemoteInterface{
public RemoteObject() throws java.rmi.RemoteException{
         // Empty constructor
}
public java.util.Date askTime() throws java.rmi.RemoteException{
    System.out.println("RemoteObject.askTime called" + new java.util.Date() + "\n");
    return new java.util.Date();
}
public void tellTime(java.util.Date d) throws java.rmi.RemoteException{
    System.out.println("RemoteObject.tellTime called" + d + "\n");
}
}

Make a Server

The server should have a 'main' that ...

Installs a new security manager
Possibly starts an rmiregistry (if it's not already running)
Creates an object of type equal to the interface of the remote object you just made.
Binds the object to a name on the registry

public class Server{ public static void main(String[] args){ try{ System.setSecurityManager(new java.rmi.RMISecurityManager()); RemoteInterface v=new RemoteObject(); java.rmi.registry.LocateRegistry.createRegistry(5099); java.rmi.Naming.rebind("//:5099/count", v); }catch(java.rmi.UnknownHostException x){x.printStackTrace();} catch(java.rmi.RemoteException x){x.printStackTrace();} catch(java.net.MalformedURLException x){x.printStackTrace();} catch(Exception x){x.printStackTrace();} } }

Make a Client

The client should

Call lookup to get an object of type remoteobject_stub
Use that to access the remote object

public class Client{
public static void main(String[] args){
    RemoteInterface s=null;
    try{
      s=(RemoteInterface)java.rmi.Naming.lookup("rmi://euclid.nmu.edu:5099/count");
      s.tellTime(new java.util.Date());
      System.out.println(s.askTime());
    }catch (Exception x){x.printStackTrace();}
}
}

Running it

See howto-start.html