started task 7

week3_TinsaeGhilay/Task 3/src/client/Client.java

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+package client;
+
+// Client/Client.java class represents the client that has to relay on the Hello engine
+// to perform tasks remotely.
+// it needs the Hello interface from Hello package
+import hello.Hello;
+
+// it also needs those to access the registry,
+// so it can get remote object reference of the server
+import java.rmi.registry.LocateRegistry;
+import java.rmi.registry.Registry;
+import java.util.Scanner;
+
+public class Client {
+    private Client() {
+    }
+
+    public static void main(String[] args) {
+
+        // normally, the address of the server is passed here on the command line as an
+        // argument
+        // we get that address from args[0] if provided, else we use null for localhost
+        String host = (args.length < 1) ? null : args[0];
+        String name = "Hello";
+
+        try (Scanner scanner = new Scanner(System.in);) {
+
+            // get the registry from host(server)
+            Registry registry = LocateRegistry.getRegistry(host);
+
+            // look up the remote object by name in the registry
+            // stub is the a reference to the remote object
+            Hello stub = (Hello) registry.lookup(name);
+            String response = stub.sayHello();
+            System.out.println("response: " + response);
+
+        } catch (Exception e) {
+            System.err.println("Client exception: " + e.getMessage());
+        }
+    }
+}

week3_TinsaeGhilay/Task 3/src/hello/Hello.java

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+package hello;
+
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+
+// this interface extends the interface "java.rmi.Remote"
+// so its methods can be invoked from another Java virtual machine
+public interface Hello extends Remote {
+
+    // say hello method, This is a repeat of task 1(done as part of learning RMI)
+    String sayHello() throws RemoteException;
+}

week3_TinsaeGhilay/Task 3/src/server/Server.java

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+
+package server;
+
+import java.rmi.RemoteException;
+import java.rmi.registry.LocateRegistry;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+
+// needs the compute and task interfaces from compute package
+// define constructor for each
+// and provide an implementation for each remote method in the remote interfaces
+import hello.Hello;
+
+/**
+ * The implementation of the Compute interface for the compute engine.
+ * it has to declare the remote class to be implemented (in this case Compute
+ * (implements it)
+ */
+public class Server implements Hello {
+
+    public Server() {
+        super();
+    }
+
+    @Override
+    public String sayHello() throws RemoteException {
+        return "Hello, world!";
+    }
+
+    // entry
+    public static void main(String[] args) {
+
+        // the code provided on the tutorial was deprecated.
+        // so google led me to
+        // [this](https://docs.oracle.com/javase/8/docs/technotes/guides/rmi/hello/hello-world.html#create)
+        try {
+            String name = "Hello";
+            // create remote object that provides service (server).
+            Hello server = new Server();
+
+            // and export remote object to java RMI runtime
+            // so it may receive remote incoming calls
+            Hello stub = (Hello) UnicastRemoteObject.exportObject(server, 0);
+            // the register the remote object with java RMI registry
+            // the registry is a name service that allows clients get a reference of remote
+            // objects
+            // once a remote object is registered, callers can look up the object by name
+            // and obtain its remote object reference
+            Registry registry = LocateRegistry.getRegistry();
+            registry.rebind(name, stub);
+            System.out.println("Server bound");
+        } catch (Exception e) {
+            System.err.println("Server exception: " + e.getMessage());
+        }
+    }
+}