Initial Commit of Homework #3

08/17/2020

assignments/src/MV3500Cohort2020JulySeptember/homework3/Weissenberger/README.md

@@ -10,3 +10,10 @@ References include
 * [assignments source subdirectories](../../../../../assignments/src) show examples from previous cohorts. 
 
 Questions and innovation are always welcome, good luck!
+
+This program(s) do(es) the following:
+- send two numbers, a mathematical operator and a port number over VPN to a TCP receiver
+- the TCP receiver calculates the result and send it back to the sender over VPN using UDP!
+- the UDP receiver shows the result
+
+

assignments/src/MV3500Cohort2020JulySeptember/homework3/Weissenberger/TCPNumberReceiver.java

+package MV3500Cohort2020JulySeptember.homework3.Weissenberger;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+
+/**
+ * This class will be connected by an TCP sender over VPN (argon), calculating 
+ * a result of an equation and send the result back via UDP over VPN. 
+ * @date 08/17/2020
+ * @author Loki
+ * @group Weissenberger/Goericke
+ */
+public class TCPNumberReceiver {
+
+    // Change this to the port where the TCP server is listening
+    private static final int TCP_ARGON_SERVER_PORT = 2317;
+
+    /**
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        try {
+            
+            // ServerSocket waits for a connection from a client. 
+            System.out.println("TCPNumberReceiver has started...");
+            ServerSocket serverSocket = new ServerSocket(TCP_ARGON_SERVER_PORT);
+            InetAddress remoteAddress;
+
+            InputStream inputStream;
+            InputStreamReader inputStreamReader;
+            BufferedReader bufferedReader;
+            String clientMessage;
+            int number1, number2;
+            String calculation_Method;
+            int iUDPResultReceivingPort;
+            // Server is up and waiting (i.e. "blocked" or paused)
+            // Loop, infinitely, waiting for client connections.
+            // Stop the program somewhere else.
+            while (true) { 
+                
+                // block until connected to a client
+                try (Socket clientConnectionSocket = serverSocket.accept())
+                {
+                    // Now hook everything up (i.e. set up the streams), Java style:
+                    inputStream  = clientConnectionSocket.getInputStream();
+                    inputStreamReader = new InputStreamReader(inputStream);
+                    bufferedReader  = new BufferedReader(inputStreamReader);
+                    clientMessage = bufferedReader.readLine();
+                    number1 = Integer.parseInt(bufferedReader.readLine());
+                    number2 = Integer.parseInt(bufferedReader.readLine());
+                    calculation_Method = bufferedReader.readLine();
+                    iUDPResultReceivingPort = Integer.parseInt(bufferedReader.readLine());
+                    System.out.println("Message recived: "+clientMessage);
+                    System.out.println("Number 1 recived: "+number1);
+                    System.out.println("Number 2 recived: "+number2);
+                    System.out.println("Calc Method recived: "+calculation_Method);
+                    System.out.println("Send result to port: "+iUDPResultReceivingPort);
+                    // This includes the port and IP numbers on both sides (the socket pair).
+                    remoteAddress = clientConnectionSocket.getInetAddress();
+                    
+                    System.out.println("Send result to IP: "+remoteAddress.getHostAddress());
+                    
+                    // try to send the calculated result as a float via UDP...
+                    sendResultViaUDP(calculateResult(number1, number2, calculation_Method), remoteAddress, iUDPResultReceivingPort);
+                }
+            }
+        } catch (IOException e) {
+            System.err.println("Problem with TcpExample3Server 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!");
+            }
+        }
+    }
+    
+    private static void sendResultViaUDP(float result, InetAddress inetAddress, int port) throws IOException{
+        DatagramSocket udpSocket = null;
+        DataOutputStream  dos = null;
+        
+        try
+        {
+            // Create a UDP socket
+            udpSocket = new DatagramSocket(); // let system assign output port, then SENDING_PORT not needed
+            
+            // Put together a message with binary content. "ByteArrayOutputStream"
+            // is a java.io utility that lets us put together an array of binary
+            // data, which we put into the UDP packet.
+            
+            ByteArrayOutputStream baos = new ByteArrayOutputStream(1500); // how many bytes are in buffer?  MTU=1500 is good
+            dos = new DataOutputStream(baos); // wrapper for writing values, connects both streams
+			
+            // Put together a packet to send
+            // these types and order of variables must match on sender and receiver
+            byte[] byteArray = baos.toByteArray();
+            
+            DatagramPacket datagramPacket = new DatagramPacket(byteArray, byteArray.length, inetAddress, port);
+       
+            for (int index = 1; index <= 10; index++) 
+            {
+                dos.writeFloat  (result);
+                dos.flush(); // sends DataOutputStream to ByteArrayOutputStream
+                byteArray = baos.toByteArray();    // OK so go get the flushed result...
+                datagramPacket.setData(byteArray); // and put it in the packet...
+                udpSocket.send(datagramPacket);    // and send it away. boom gone, nonblocking.
+            
+                Thread.sleep(1000); // Send packets at rate of one per second
+                baos.reset(); // clear the output stream after sending
+            }
+            dos.close();
+        }
+        catch (IOException | InterruptedException e)
+        {
+            System.err.println("Problem with UdpSender, see exception trace:");
+            System.err.println(e);
+        } 
+        finally // clean up prior to exit, don't want to leave behind zombies
+        {
+            if (udpSocket != null)
+                udpSocket.close();
+            
+            if (dos != null)
+                dos.close();
+        }
+    }
+    
+    /**
+     * calculates the result based on given numbers and operator
+     * @param n1 first number
+     * @param n2 second number
+     * @param operator
+     * @return the result as a float
+     */
+    private static float calculateResult(int n1, int n2, String operator){
+        float result = -1;
+        switch (operator) {
+            case "+":
+                result = n1 + n2;
+                break;
+            case "-":
+                result = n1 - n2;
+                break;
+            case "*":
+                result = n1 * n2;
+                break;
+            case "/":
+                result = n1 / n2;
+                break;
+            default:
+                System.err.println(operator +" is not a valid operator!");
+                break;
+        }
+        return result;
+    }
+}

assignments/src/MV3500Cohort2020JulySeptember/homework3/Weissenberger/TCPNumberSender.java

+
+package MV3500Cohort2020JulySeptember.homework3.Weissenberger;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.net.Socket;
+
+/**
+ * This class will connect to an TCP receiver over VPN (argon) and send 
+ * two numbers
+ * @date 08/17/2020
+ * @author Loki
+ * @group Weissenberger/Goericke
+ */
+public class TCPNumberSender {
+    
+    // Change this to the IP address of the TCP server 10.1.105.9 (127.0.0.1 just for testing)
+    private static final String TCP_ARGON_SERVER_IP = "127.0.0.1";
+    // Change this to the port where the TCP server is listening
+    private static final int TCP_ARGON_SERVER_PORT = 2317;
+    // Where the result should be posted (port)
+    private static final int UDP_ARGON_RECEIVING_PORT = 1415;
+    
+    private static final int NUMBER1 = 16;
+    private static final int NUMBER2 = 2;
+    private static final String CALCULATION_METHOD = "-";
+    
+    // how many times should the number being sent
+    private static final int REPETITION = 1;
+    private static int counter = 0;
+    
+    public static void main(String[] args) throws InterruptedException {
+        
+        // Local variables
+        Socket socket;
+        OutputStream outputStream;
+        PrintStream printStream;
+        
+        try {
+            while (counter < REPETITION){
+                // increment the counter
+                counter++;
+                System.out.println("Homwork 3: TcpNumberSender creating socket over VPN...");
+
+                // We request an IP to connect to "TCP_ARGON_SERVER_IP" over 
+                // the argon VPN and port number at that IP "TCP_ARGON_SERVER_PORT". 
+                // This establishes a connection to that IP in the form of a Socket
+                // object.
+                socket = new Socket(TCP_ARGON_SERVER_IP, TCP_ARGON_SERVER_PORT); // locohost?
+
+                
+                // instanciate the streams:
+                outputStream = socket.getOutputStream();
+                printStream = new PrintStream(outputStream);
+                // send a first text to server
+                printStream.println("This is message from client.");
+                printStream.flush();
+                // wait 1 second
+                Thread.sleep(1000);   
+                
+                // sending number 1
+                printStream.println(NUMBER1);
+                // sending number 2
+                printStream.println(NUMBER2);
+                // sending calc method
+                printStream.println(CALCULATION_METHOD);
+                // sending the port where the result should be send to
+                printStream.println(UDP_ARGON_RECEIVING_PORT);
+                printStream.flush();
+                // wait 1 second
+                Thread.sleep(1000);   
+                
+                System.out.println("==================================================");
+                System.out.println(NUMBER1+" and "+NUMBER2+" were sent to server. Calculating method was: "+CALCULATION_METHOD);
+                
+                // close TCP socket to server
+                socket.close();
+            } // end while(true)
+        } 
+        catch (IOException e)
+        {
+            System.err.println("Problem with TCPNumberSender networking:");
+            System.err.println("Error: " + e);
+            
+            if (e instanceof java.net.BindException) {
+                System.err.println("*** Be sure to stop any other running instances of programs using this port: "+TCP_ARGON_SERVER_PORT);
+            }
+        }
+        finally // occurs after any other activity when shutting down
+        {
+            System.out.println();
+            System.out.println("TCPNumberSender exit");
+        }
+    }
+
+}

assignments/src/MV3500Cohort2020JulySeptember/homework3/Weissenberger/UDPResultReceiver.java

+
+package MV3500Cohort2020JulySeptember.homework3.Weissenberger;
+
+import java.io.ByteArrayInputStream;
+import java.io.DataInputStream;
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+
+/**
+ * This class will be connected by an UDP sender over VPN (argon) 
+ * @date 08/17/2020
+ * @author Loki
+ * @group Weissenberger/Goericke
+ */
+public class UDPResultReceiver {
+
+    public static final int    RECEIVING_PORT = 1415;
+
+    /**
+     * @param args the command line arguments
+     * @throws java.io.IOException
+     */
+    public static void main(String[] args) throws IOException 
+    {
+        DatagramSocket udpSocket = null;
+        
+        try
+        {
+            System.out.println(UDPResultReceiver.class.getName() + " started...");
+            
+            // Create a UDP socket
+            udpSocket = new DatagramSocket(RECEIVING_PORT);
+            udpSocket.setReceiveBufferSize(1500); // how many bytes are in buffer?  MTU=1500 is good
+            udpSocket.setBroadcast(false);        // we're just receiving here
+            
+            byte[] byteArray = new byte[1500];
+            DatagramPacket receivePacket = new DatagramPacket(byteArray, byteArray.length);
+            
+            ByteArrayInputStream bais = new ByteArrayInputStream(byteArray);
+            DataInputStream dis = new DataInputStream(bais);
+            
+            float result;
+            
+            // You need a new receiving packet to read from every packet received
+            while (true)
+            {
+                udpSocket.receive(receivePacket); // blocks until packet is received
+                
+                result  = dis.readFloat();
+                
+                dis.reset(); // now clear the input stream after reading, in preparation for next loop
+                
+                System.out.println("Calculated result: "+result);
+                
+            }
+        }
+        catch(IOException e)
+        {
+            System.err.println("Problem with UdpReceiver, see exception trace:");
+            System.err.println(e);
+        } 
+        finally // clean up prior to exit, don't want to leave behind zombie socket
+        {
+            if (udpSocket != null)
+                udpSocket.close();
+            System.out.println(UDPResultReceiver.class.getName() + " complete."); // all done
+        }
+    }
+
+}