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assignments/src/MV3500Cohort2019JulySeptember/homework2/Fetterolf/FetterolfHomework2Client.java

+package MV3500Cohort2019JulySeptember.homework2.Fetterolf;
+
+import MV3500Cohort2019JulySeptember.homework2.*;
+import java.io.*;
+import java.net.*;
+
+/**
+ * Before, we always used telnet (netcat) to connect to the server. Here we are
+ * now writing our own program to do the connection.
+ *
+ * As you will see, when we run this after we start the server we will see the
+ * same string telnet printed, sent by the server. The output at the server will
+ * show different socket pairs for each time the loop iterates.
+ *
+ * @author mcgredo
+ */
+public class FetterolfHomework2Client {
+
+    // IPv6 String constant for localhost address, similarly IPv4 127.0.0.1
+    public final static String LOCALHOST = "0:0:0:0:0:0:0:1";
+
+    public static void main(String[] args) {
+        
+        String serverMessage;
+        Socket socket;
+        InputStream is;
+        InputStreamReader isr;
+        BufferedReader br;
+        
+        try {
+            System.out.println("Answer this question.");
+            System.out.println("What is the best country in the world?");
+            
+            while (true) {
+                
+                // We request an IP to connect to ("localhost") and
+                // port number at that IP (2317). This establishes
+                // a connection to that IP in the form of a Socket
+                // object; the server uses a ServerSocket to wait for
+                // connections.
+                socket = new Socket(LOCALHOST, 2317); // locohost?
+
+                // Now hook everything up (i.e. set up the streams), Java style:
+                OutputStream os = socket.getOutputStream();
+                OutputStreamWriter osw = new OutputStreamWriter(os);
+                BufferedWriter bw = new BufferedWriter(osw);
+
+               is = socket.getInputStream();
+               isr = new InputStreamReader(is);
+               br = new BufferedReader(isr);
+
+                
+                serverMessage = br.readLine();
+                System.out.println(serverMessage + "?" + "\n" + "No way");
+
+                System.out.println("Try again.");  
+
+                //String update = br.readLine();
+                // String sendUpdate = update + "\n";
+                //System.out.println("The correct answer is MERICA");
+
+              
+            } // end while(true)
+        } catch (IOException e) {
+            System.err.println("Problem with TcpExample3ServerClient networking:"); // describe what is happening
+            System.err.println("Error: " + e);
+
+            // Provide more helpful information to user if exception occurs due to running twice at one time
+            if (e instanceof java.net.BindException) {
+                System.err.println("*** Be sure to stop any other running instances of programs using this port!");
+            }
+        } 
+        
+        finally {
+
+            // program exit: tell somebody about that
+            System.out.println("\nclient exit");
+        }
+    }
+}

assignments/src/MV3500Cohort2019JulySeptember/homework2/Fetterolf/FetterolfHomework2Server.java

+package MV3500Cohort2019JulySeptember.homework2.Fetterolf;
+
+import MV3500Cohort2019JulySeptember.homework2.*;
+import java.io.*;
+import java.net.*;
+import java.util.Scanner;
+
+/**
+ * Very slightly more complex than example1, further modifying example2. The
+ * only thing this does differently is introduce a loop into the response, so
+ * you don't have to restart the program after one response. Also, it prints out
+ * the socket pair the server sees. Run the program via telnet several times and
+ * compare the socket pairs.
+ *
+ * telnet (nc) localhost 2317
+ *
+ * If you're sophisticated you can contact the instructor's computer while
+ * running this program.
+ *
+ * telnet (nc) [ipNumberOfServerLaptop] 2317
+ *
+ * and have the instructor display the socket pairs received.
+ *
+ * @author mcgredo
+ */
+public class FetterolfHomework2Server {
+
+    public static void main(String[] args) {
+        try {
+
+            System.out.println("Server has started..."); // it helps debugging to put this on console first
+
+            ServerSocket serverSocket = new ServerSocket(2317);
+
+            while (true) {
+
+                Socket clientConnection = serverSocket.accept();
+
+                OutputStream os = clientConnection.getOutputStream();
+                PrintStream ps = new PrintStream(os);
+
+                ps.println("Venezuela");
+
+                // Print some information locally about the Socket
+                // connection. This includes the port and IP numbers
+                // on both sides (the socket pair.)
+                InetAddress localAddress = clientConnection.getLocalAddress();
+                InetAddress remoteAddress = clientConnection.getInetAddress();
+
+                int localPort = clientConnection.getLocalPort();
+                int remotePort = clientConnection.getPort();
+
+                // My socket pair connection looks like this, to localhost:
+                // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54876 ))
+                // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54881 ))
+                //
+                // Why is the first IP/port the same, while the second set has
+                // different ports?
+                System.out.println("Socket pair: (( " + localAddress.toString().trim() + ", " + localPort + " ), ( "
+                        + remoteAddress.toString() + ", " + remotePort + " ))");
+
+                InputStream is = clientConnection.getInputStream();
+                InputStreamReader isr = new InputStreamReader(is);
+                BufferedReader br = new BufferedReader(isr);
+
+                String serverMessage = br.readLine();
+                System.out.println("This time try " + serverMessage);
+
+                // Notice the use of flush() and close(). Without
+                // the close() to Socket object may stay open for 
+                // a while after the client has stopped needing this
+                // connection. Close() explicitly ends the connection.
+                ps.flush();
+                clientConnection.close(); 
+            }
+        } catch (IOException e) {
+            System.err.println("Problem with Server networking: " + e);
+
+            // Provide more helpful information to user if exception occurs due to running twice at one time
+            if (e instanceof java.net.BindException) {
+                System.err.println("*** Be sure to stop any other running instances of programs using this port!");
+            }
+        }
+    }
+}