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Commit 23f46f26 authored by Brutzman, Don's avatar Brutzman, Don
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assignments go into assignments tree instead

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examples/src/TcpExamples/Assignment1TCPExample3ClientChange.java deleted 100644 → 0
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package TcpExamples;
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 assignment 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");
}
}
}
examples/src/TcpExamples/Assignmnet1TCPExample3ServerChange.java deleted 100644 → 0
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− 112
View file @ 5061e4da
package TcpExamples;
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!");
}
}
}
}
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