diff --git a/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignment1TCPExample3ClientChange.java b/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignment1TCPExample3ClientChange.java new file mode 100644 index 0000000000000000000000000000000000000000..ba25907b9275ea5692aba14e6d93507016499750 --- /dev/null +++ b/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignment1TCPExample3ClientChange.java @@ -0,0 +1,104 @@ +package MV3500Cohort2023MarchJune.homework1.Cecil; + +import java.io.*; +import java.net.*; + +/** + * This is Assignment 1 where I have modified the given code from TCPExample3Client + * -sleep time has been extended to give more time in between loops + * -Initial print line has been altered to reflect assingnment 1 + * -Loop only runs a finite number of times ,10. + * 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 + * @author brutzman@nps.edu + */ +public class Assignment1TCPExample3ClientChange +{ + /** Default constructor */ + public Assignment1TCPExample3ClientChange() + { + // default constructor + } + /** IPv6 String constant for localhost address, similarly IPv4 127.0.0.1 + * @see <a href="https://en.wikipedia.org/wiki/localhost">https://en.wikipedia.org/wiki/localhost</a> + * @see <a href="https://en.wikipedia.org/wiki/IPv6_address">https://en.wikipedia.org/wiki/IPv6_address</a> + */ + public final static String LOCALHOST = "0:0:0:0:0:0:0:1"; + + /** + * Program invocation, execution starts here + * @param args command-line arguments + */ + public static void main(String[] args) + { + // Local variables/fields + Socket socket = null; + InputStream is; + Reader isr; + BufferedReader br; + String serverMessage; + int clientLoopCount = 0; + int numberOfLoops = 10; + + try { + while (clientLoopCount < numberOfLoops) + { + clientLoopCount++; // increment at beginning of loop for reliability + System.out.println(Assignment1TCPExample3ClientChange.class.getName() + " creating socket..."); + + // 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: + is = socket.getInputStream(); + isr = new InputStreamReader(is); + br = new BufferedReader(isr); + + // Read a single line written by the server. We'd + // do things a bit differently if there were many lines to be read + // from the server instead of one only. + serverMessage = br.readLine(); + System.out.println("======================Assignment1==========================="); + + System.out.print ("Client loop " + clientLoopCount + ": "); + System.out.println("now we're talking!"); + System.out.println("The message the server sent was: '" + serverMessage + "'"); + // socket gets closed, either automatically/silently by this code (or possibly by the server) + + Thread.sleep(800l); // slow things down, for example 500l (long) = 500 msec + + } // end while(true) // infinite loops are dangerous, be sure to kill this process! + } + catch (IOException | InterruptedException e) + { + System.err.println("Problem with " + TcpExample3Client.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!"); + } + } + finally // occurs after any other activity when shutting down + { + try { + if (socket != null) + socket.close(); + } catch (IOException e) {} + + // program exit: tell somebody about that happening. Likely cause: server drops connection. + System.out.println(); + System.out.println(TcpExample3Client.class.getName() + " exit"); + } + } +} diff --git a/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignmnet1TCPExample3ServerChange.java b/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignmnet1TCPExample3ServerChange.java new file mode 100644 index 0000000000000000000000000000000000000000..d6a23e470d6e34651991eb12057b769bd54eff12 --- /dev/null +++ b/assignments/src/MV3500Cohort2023MarchJune/homework1/Cecil/Assignmnet1TCPExample3ServerChange.java @@ -0,0 +1,112 @@ +package MV3500Cohort2023MarchJune.homework1.Cecil; + +import java.io.*; +import java.net.*; + +/** + * This is Assignment 1 where I have modified the given code from TCPExample3Server + *-server response message changed + * + * 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 + * @author brutzman@nps.edu + */ +public class Assignmnet1TCPExample3ServerChange +{ + /** Default constructor */ + public Assignmnet1TCPExample3ServerChange() + { + // default constructor + } + /** + * Program invocation, execution starts here + * If already compiled, can run using console in directory ../../build/classes/ by invoking \ + * java -classpath . TcpExamples.TcpExample3Server + * @param args command-line arguments + */ + public static void main(String[] args) { + try { + + // ServerSocket waits for a connection from a client. + // Notice that it is outside the loop; ServerSocket + // needs to be made only once. + System.out.println(Assignmnet1TCPExample3ServerChange.class.getName() + " has started..."); // it helps debugging to put this on console first + + ServerSocket serverSocket = new ServerSocket(2317); + OutputStream os; + PrintStream ps; + InetAddress localAddress, remoteAddress; + int localPort, remotePort; + int serverLoopCount = 0; + + // 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()) + { + serverLoopCount++; // increment at beginning of loop for reliability + + // Now hook everything up (i.e. set up the streams), Java style: + os = clientConnectionSocket.getOutputStream(); + ps = new PrintStream(os); + ps.println("This is response " + serverLoopCount + " produced by the server, " + + Assignmnet1TCPExample3ServerChange.class.getName()); // this gets sent back to client! + + // Print some information locally about the Socket connection. + // This includes the port and IP numbers on both sides (the socket pair). + localAddress = clientConnectionSocket.getLocalAddress(); + remoteAddress = clientConnectionSocket.getInetAddress(); + localPort = clientConnectionSocket.getLocalPort(); + remotePort = clientConnectionSocket.getPort(); + + System.out.print ("Server loop " + serverLoopCount + ": "); + + // 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(TcpExample3Server.class.getName() + " socket pair showing host name, address, port:"); + System.out.println(" (( " + + localAddress.getHostName() + "=" + localAddress.getHostAddress() + ", " + localPort + " ), ( " + + remoteAddress.getHostName() + "=" + remoteAddress.getHostAddress() + ", " + remotePort + " ))"); + + if ( localAddress.getHostName().equals( localAddress.getHostAddress()) || + remoteAddress.getHostName().equals(remoteAddress.getHostAddress())) + System.out.println(" note HostName matches address if host has no DNS name"); + + // Notice the use of flush() and try w/ resources. Without + // the try w/ resources the Socket object may stay open for + // a while after the client has stopped needing this + // connection. try w/ resources explicitly ends the connection. + ps.flush(); + // like it or not, you're outta here! + } + } + } catch (IOException e) { + System.err.println("Problem with " + TcpExample3Server.class.getName() + " 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!"); + } + } + } +} diff --git a/assignments/src/MV3500Cohort2023MarchJune/homework1/Chojnacki/Assignment1Client.java b/assignments/src/MV3500Cohort2023MarchJune/homework1/Chojnacki/Assignment1Client.java index 5030228bcadbaeaf2502a4def91af170752945fa..02fc826d6b1b4a01bb2ed4edac08ef485d08d995 100644 --- a/assignments/src/MV3500Cohort2023MarchJune/homework1/Chojnacki/Assignment1Client.java +++ b/assignments/src/MV3500Cohort2023MarchJune/homework1/Chojnacki/Assignment1Client.java @@ -2,9 +2,10 @@ package MV3500Cohort2023MarchJune.homework1.Chojnacki; import java.io.*; import java.net.*; +import java.text.SimpleDateFormat; +import java.util.Calendar; /** - * Testing * This is Assignment 1 where I have modified the given code from TCPExample3Client * -sleep time has been extended to give more time in between loops * -Initial print line has been altered to reflect assignment 1 @@ -72,7 +73,8 @@ public class Assignment1Client System.out.println("======================Assignment1==========================="); System.out.print ("Client loop " + clientLoopCount + ": "); - System.out.println("We are connected to the server!"); + String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime()); + System.out.println("The current system time is " + timeStamp + "!"); System.out.println("The message the server sent was: '" + serverMessage + "'"); // socket gets closed, either automatically/silently by this code (or possibly by the server)