Merge origin/master

assignments/src/MV3500Cohort2021JulySeptember/homework1/PughTcp2ConnectionCounting

+package MV3500Cohort2021JulySeptember.homework1.Pugh;
+
+import java.io.*;
+import java.net.*;
+
+/**
+ * Very slightly more complex than example1. 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.
+ *
+ * <code>telnet localhost 2317</code>
+ *
+ * If you're sophisticated you can contact the instructor's computer while
+ * running this program.
+ *
+ * <code>telnet ipOfServersLaptop 2317</code>
+ *
+ * And have that machine display the socket pairs received.
+ *
+ * @author pugh
+ * @author brutzman
+ */
+public class PughTcp2ConnectionCounting {
+
+    /**
+     * Program invocation, execution starts here
+     *
+     * @param args command-line arguments
+     */
+    public static void main(String[] args) {
+        try {
+            System.out.println("TcpExample2ConnectionCounting has started and is waiting for a connection.");
+            System.out.println("Get Ready To Network!!!");
+            System.out.println("  help: https://savage.nps.edu/Savage/developers.html#telnet");
+            System.out.println("  enter (nc localhost 2317) or (telnet localhost 2317)...");
+
+            // ServerSocket waits for a connection from a client. 
+            // Notice that it is outside the loop; ServerSocket needs to be made only once.
+            int connectionCount = 0; // state variable
+
+            ServerSocket serverSocket = new ServerSocket(2317); // server decides here what port to listen on.
+            // of interest: often client doesn't care what port it uses locally when connecting to that server port.
+
+            // Loop, infinitely, waiting for client connections.
+            // Stop the program somewhere else.
+            while (true) {
+                // blocks! then proceeds once a connection is "accept"ed
+                try ( Socket clientConnection = serverSocket.accept()) {
+                    connectionCount++; // got another one!
+
+                    OutputStream os = clientConnection.getOutputStream();
+                    PrintStream ps = new PrintStream(os);
+
+                    ps.println("This client response was written by server " + PughTcp2ConnectionCounting.class.getName()); // to remote client
+                    System.out.println("This server response was written by server " + PughTcp2ConnectionCounting.class.getName() + "\n"); // to server console
+                    if (connectionCount % 2 == 1) {
+                        System.out.println("Go\n");
+                    }
+                    if (connectionCount % 2 == 0) {
+                        System.out.println("Gators!\n");
+                    }
+                    if (connectionCount % 3 == 1 && connectionCount != 0) {
+                        System.out.println("O'Doyle Rules!!! \n");
+                    }
+                    ps.println("You were connection #" + connectionCount + ", by my count");
+
+                    // 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();       // remember the prior question, why are 2 ports different?
+
+                    // 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 )) note IPv6
+                    // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54881 ))
+                    //
+                    // Why is first IP/port the same, while the second set has different ports?
+                    System.out.println("Socket pair: (( " + localAddress.toString() + ", " + localPort + " ), ( "
+                            + remoteAddress.toString() + ", " + remotePort + " ))");
+
+                    System.out.println("got another connection, #" + connectionCount); // report progress
+
+                    // 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();
+                }
+            }
+        } catch (IOException e) {
+            System.err.println("Problem with  " + PughTcp2ConnectionCounting.class.getName() + " 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!");
+            }
+        }
+    }
+}

assignments/src/MV3500Cohort2021JulySeptember/homework1/PughTcp2ConnectionCounting.java

+package MV3500Cohort2021JulySeptember.homework1.Pugh;
+
+import java.io.*;
+import java.net.*;
+
+/**
+ * Very slightly more complex than example1. 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.
+ *
+ * <code>telnet localhost 2317</code>
+ *
+ * If you're sophisticated you can contact the instructor's computer while
+ * running this program.
+ *
+ * <code>telnet ipOfServersLaptop 2317</code>
+ *
+ * And have that machine display the socket pairs received.
+ *
+ * @author pugh
+ * @author brutzman
+ */
+public class PughTcp2ConnectionCounting {
+
+    /**
+     * Program invocation, execution starts here
+     *
+     * @param args command-line arguments
+     */
+    public static void main(String[] args) {
+        try {
+            System.out.println("TcpExample2ConnectionCounting has started and is waiting for a connection.");
+            System.out.println("Get Ready To Network!!!");
+            System.out.println("  help: https://savage.nps.edu/Savage/developers.html#telnet");
+            System.out.println("  enter (nc localhost 2317) or (telnet localhost 2317)...");
+
+            // ServerSocket waits for a connection from a client. 
+            // Notice that it is outside the loop; ServerSocket needs to be made only once.
+            int connectionCount = 0; // state variable
+
+            ServerSocket serverSocket = new ServerSocket(2317); // server decides here what port to listen on.
+            // of interest: often client doesn't care what port it uses locally when connecting to that server port.
+
+            // Loop, infinitely, waiting for client connections.
+            // Stop the program somewhere else.
+            while (true) {
+                // blocks! then proceeds once a connection is "accept"ed
+                try ( Socket clientConnection = serverSocket.accept()) {
+                    connectionCount++; // got another one!
+
+                    OutputStream os = clientConnection.getOutputStream();
+                    PrintStream ps = new PrintStream(os);
+
+                    ps.println("This client response was written by server " + PughTcp2ConnectionCounting.class.getName()); // to remote client
+                    System.out.println("This server response was written by server " + PughTcp2ConnectionCounting.class.getName() + "\n"); // to server console
+                    if (connectionCount % 2 == 1) {
+                        System.out.println("Go\n");
+                    }
+                    if (connectionCount % 2 == 0) {
+                        System.out.println("Gators!\n");
+                    }
+                    if (connectionCount % 3 == 1 && connectionCount != 0) {
+                        System.out.println("O'Doyle Rules!!! \n");
+                    }
+                    ps.println("You were connection #" + connectionCount + ", by my count");
+
+                    // 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();       // remember the prior question, why are 2 ports different?
+
+                    // 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 )) note IPv6
+                    // Socket pair: (( /0:0:0:0:0:0:0:1, 2317 ), ( /0:0:0:0:0:0:0:1, 54881 ))
+                    //
+                    // Why is first IP/port the same, while the second set has different ports?
+                    System.out.println("Socket pair: (( " + localAddress.toString() + ", " + localPort + " ), ( "
+                            + remoteAddress.toString() + ", " + remotePort + " ))");
+
+                    System.out.println("got another connection, #" + connectionCount); // report progress
+
+                    // 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();
+                }
+            }
+        } catch (IOException e) {
+            System.err.println("Problem with  " + PughTcp2ConnectionCounting.class.getName() + " 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!");
+            }
+        }
+    }
+}

examples/src/TcpExamples/TcpExample2ConnectionCounting.java

@@ -33,7 +33,16 @@ public class TcpExample2ConnectionCounting
         {
             System.out.println("TcpExample2ConnectionCounting has started and is waiting for a connection.");
             System.out.println("  help: https://savage.nps.edu/Savage/developers.html#telnet");
-            System.out.println("  enter (nc localhost 2317) or (telnet localhost 2317)..." );
+            // Where are we?  In other words, what is our host number? Advertise it
+            // https://stackoverflow.com/questions/9481865/getting-the-ip-address-of-the-current-machine-using-java
+            String localHostAddress = Inet4Address.getLocalHost().toString();
+            System.out.println("Local host address is " + localHostAddress);
+            if (localHostAddress.contains("/"))
+                localHostAddress = localHostAddress.substring(localHostAddress.indexOf("/")+1);
+            // show localhost IP number to facilitate connections over local area network (LAN, WAN)
+            System.out.println("  enter (nc localhost   2317) or (telnet localhost   2317) for local operation" );
+            System.out.println("  enter (nc "     + localHostAddress + " 2317) or " +
+                                       "(telnet " + localHostAddress + " 2317)..." );
 			
             // ServerSocket waits for a connection from a client. 
             // Notice that it is outside the loop; ServerSocket needs to be made only once.
@@ -42,7 +51,7 @@ public class TcpExample2ConnectionCounting
             
             ServerSocket serverSocket = new ServerSocket(2317); // server decides here what port to listen on.
 			// of interest: often client doesn't care what port it uses locally when connecting to that server port.
-
+                
             // Loop, infinitely, waiting for client connections.
             // Stop the program somewhere else.
             while(true)