Merge origin/master

assignments/src/MV3500Cohort2019JulySeptember/homework1/BoronTcpExample1Telnet1.java

+package MV3500Cohort2019JulySeptember.homework1;
+
+import java.io.*;
+import java.net.*;
+import java.sql.Timestamp;
+
+/**
+ * The simplest possible TCP network program. It listens for
+ * a connection, from telnet (telnet localhost 2317) or a program
+ * you write, which we will do later. Right now the TcpExample simply
+ * writes a string in response to a connection.
+ * 
+ * Modifying his program is the basis for Assignment 1.
+ * 
+ * Testing the running server program from telnet looks like this:
+ * 
+ * it154916:projects mcgredo$ telnet localhost 2317
+ * Trying ::1...
+ * Connected to localhost.
+ * Escape character is '^]'.
+ * This was written by the server
+ * Connection closed by foreign host.
+ * 
+ * Notice that "This was written by the server" matches 
+ * what is written by the code below, over the output stream.
+ * 
+ * After this first connection the program below drops out
+ * the bottom of the program, and does not repeat itself.
+ * The program exits.
+ * 
+ * @author mcgredo, brutzman``  
+ */
+public class BoronTcpExample1Telnet1 
+{
+    public static void main(String[] args) 
+    {
+        try
+        {
+            System.out.println("TcpExample1Telnet has started and is waiting for a connection.");
+            System.out.println("  help: https://savage.nps.edu/Savage/developers.html#telnet");
+            System.out.println("  enter (telnet localhost 2317) or (nc localhost 2317)..." );
+			
+            // The ServerSocket waits for a connection from a client.
+            // It returns a Socket object when the connection occurs.
+            ServerSocket serverSocket = new ServerSocket(2317);
+            
+            // The Socket object represents the connection between
+            // the server and client, including a full duplex connection
+            Socket clientConnection = serverSocket.accept();
+            
+            // Use Java io classes to write text (as opposed to
+            // unknown bytes of some sort) to the client
+            OutputStream os = clientConnection.getOutputStream();
+            PrintStream  ps = new PrintStream(os);
+            
+                    Timestamp timestamp = new Timestamp(System.currentTimeMillis());
+                    
+                    ps.println("This client response was written by Capt. Jonathan Boron."); // to remote clientnc
+                    ps.println("Connection achieved at time: " + timestamp);
+                    
+            System.out.println("This server response was written by Capt. Jonathan Boron."); // to server console
+                 System.out.println("Connection achieved at time: " + timestamp);
+            // "flush()" in important in that it forces a write 
+            // across what is in fact a slow connection
+            ps.flush();
+            
+            clientConnection.close();
+            System.out.println("Handshake completed successfully.");
+        }
+        catch(IOException e)
+        {
+            System.out.println("problem with networking: " + e);
+//          if (e.getClass() == java.net.BindException) // TODO whazzup?
+            if (e.getMessage().equals("Address already in use: NET_Bind"))
+                System.out.println("Be sure to stop any other running instances of this program.");
+        }
+    }
+}

assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorCopyTcpExample1Telnet.java → assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorTcpExample1Telnet.java

@@ -29,7 +29,7 @@ import java.net.*;
  * 
  * @author mcgredo, brutzman``  
  */
-public class BrutzmanRefactorCopyTcpExample1Telnet 
+public class BrutzmanRefactorTcpExample1Telnet 
 {
     public static void main(String[] args) 
     {
@@ -65,9 +65,15 @@ public class BrutzmanRefactorCopyTcpExample1Telnet
         catch(IOException e)
         {
             System.out.println("problem with networking: " + e);
-//          if (e.getClass() == java.net.BindException) // TODO whazzup?
-            if (e.getMessage().equals("Address already in use: NET_Bind"))
-                System.out.println("Be sure to stop any other running instances of this program.");
+
+            // Program modification: provide more helpful information to user if
+            // exception occurs when running twice at one time
+            
+            // brute force exception checking, can be brittle if exection message changes
+            // if (e.getMessage().equals("Address already in use: NET_Bind")) 
+
+            if (e instanceof java.net.BindException)
+                System.out.println("Be sure to stop any other running instances of this program!");
         }
     }
 }

examples/nbproject/configs/TcpExample1Telnet.properties

+main.class=TcpExamples.TcpExample1Telnet

examples/nbproject/configs/TcpExample2ConnectionCounting.properties

+main.class=TcpExamples.TcpExample2ConnectionCounting

examples/nbproject/configs/TcpExample3Client.properties

+main.class=TcpExamples.TcpExample3Client

examples/nbproject/configs/TcpExample3Server.properties

+main.class=TcpExamples.TcpExample3Server

examples/nbproject/configs/TcpExample4Client.properties

+main.class=TcpExamples.TcpExample4Client

examples/nbproject/configs/TcpExample4ThreadServer.properties

+main.class=TcpExamples.TcpExample4ThreadServer

examples/nbproject/project.properties

@@ -60,6 +60,7 @@ javac.test.processorpath=\
 javadoc.additionalparam=
 javadoc.author=false
 javadoc.encoding=${source.encoding}
+javadoc.html5=false
 javadoc.noindex=false
 javadoc.nonavbar=false
 javadoc.notree=false

examples/src/TcpExamples/TcpExample1Telnet.java

@@ -64,7 +64,11 @@ public class TcpExample1Telnet
         }
         catch(IOException e)
         {
-            System.out.println("problem with networking: " + e);
+            System.out.println("Problem with TcpExample1Telnet networking:"); // describe what is happening
+            System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
         }
     }
 }

examples/src/TcpExamples/TcpExample2ConnectionCounting.java

@@ -27,6 +27,7 @@ public class TcpExample2ConnectionCounting
         try
         {
             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)..." );
 			
             // ServerSocket waits for a connection from a client. 
@@ -83,7 +84,11 @@ public class TcpExample2ConnectionCounting
        }
         catch(IOException e)
         {
-            System.out.println("problem with networking: " + e);
+            System.out.println("Problem with TcpExample2ConnectionCounting networking:"); // describe what is happening
+            System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
         }
     }
 }

examples/src/TcpExamples/TcpExample3Client.java

@@ -41,13 +41,16 @@ public class TcpExample3Client {
 				String serverMessage = br.readLine();
 				System.out.println("==================================================");
 				System.out.println("Now we're talking!");
-				System.out.println("The message the server sent was " + serverMessage);
+				System.out.println("The message the server sent was '" + serverMessage + "'");
 				// socket gets closed, either automatically/silently this code (or possibly by server)
 			} // end while(true)
 		} 
 		catch (IOException e) {
-			System.out.println("Problem with client: "); // describe what is happening
-			System.out.println(e);
+			System.out.println("Problem with TcpExample3ServerClient networking:"); // describe what is happening
+            System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
 		}
 		// program exit: tell somebody about that
 		System.out.println("client exit");

examples/src/TcpExamples/TcpExample3Server.java

@@ -4,8 +4,8 @@ import java.io.*;
 import java.net.*;
 
 /**
- * Very slightly more complex than example1. A complete copy of example 2. The
- * only thing this does differently is introduce a loop into the response, so
+ * Very slightly more complex than example1, further modifying example 2.
+ * 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.
@@ -17,7 +17,7 @@ import java.net.*;
  *
  * telnet [ipNumberOfServerLaptop] 2317
  *
- * And have him display the socket pairs he got.
+ * And have the instructor display the socket pairs received.
  *
  * @author mcgredo
  */
@@ -31,7 +31,7 @@ public class TcpExample3Server {
 			// Notice that it is outside the loop; ServerSocket
 			// needs to be made only once.
 
-			System.out.println("TcpExample3Server has really started..."); // it helps debugging to put this on console first
+			System.out.println("TcpExample3Server has started..."); // it helps debugging to put this on console first
 			ServerSocket serverSocket = new ServerSocket(2317);
 
 			// Server is up and waiting (i.e. "blocked" or paused)
@@ -45,11 +45,10 @@ public class TcpExample3Server {
 				OutputStream os = clientConnection.getOutputStream();
 				PrintStream  ps = new PrintStream(os);
 
-				ps.println("This was written by the server"); // this goes back to client!
+				ps.println("This message was produced by the server."); // 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.)
+				// 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();
 
@@ -60,8 +59,7 @@ public class TcpExample3Server {
 				// 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?
+				// Why is the first IP/port the same, while the second set has different ports?
 				System.out.println("TcpExample3Server socket pair: (( " + localAddress.toString() + ", " + localPort + " ), ( "
 						+ remoteAddress.toString() + ", " + remotePort + " ))");
 
@@ -73,8 +71,12 @@ public class TcpExample3Server {
 				clientConnection.close(); // like it or not, you're outta here!
 			}
 		} 
-		catch (IOException e) {
-			System.out.println("problem with networking");
+		catch (IOException e)
+        {
+			System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
 		}
 	}
 }

examples/src/TcpExamples/TcpExample4Client.java

@@ -45,7 +45,7 @@ public class TcpExample4Client
 				long   readTime = System.currentTimeMillis();
 				long timeLength = readTime - startTime;
 
-				System.out.println("TcpExample4Client: message received from server=" + serverMessage);
+				System.out.println("TcpExample4Client: message received from server='" + serverMessage + "'");
 				System.out.println("TcpExample4Client: time msec required for read=" + timeLength);
 				System.out.println("==================================================");
 				// To push this further, launch multiple copies of TcpExample4Client simultaneously
@@ -54,8 +54,11 @@ public class TcpExample4Client
         }
         catch(IOException e)
         {
-            System.out.println("Problem with TcpExample4Client, see exception trace:");
-            System.out.println(e);
+            System.out.println("Problem with TcpExample4Client networking:networking:"); // describe what is happening
+            System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
         }
     }
 }
\ No newline at end of file

examples/src/TcpExamples/TcpExample4HandlerThread.java

@@ -8,7 +8,7 @@ import java.net.*;
 /**
  * Handles all the logic associated with one connection
  * by running in a thread of its own. This is the server
- * portion as well, so we artifically invent what happens
+ * portion as well, so we artificially invent what happens
  * if the server can't respond to a connection for 10 sec.
  * 
  * @author Don McGregor
@@ -45,19 +45,22 @@ public class TcpExample4HandlerThread extends Thread
              OutputStream os = socket.getOutputStream();
               PrintStream ps = new PrintStream(os);
 
-			 final long TIMEOUT = 10000; // 10000 milliseconds = 10 seconds
+			 final long TIMEOUT = 2000; // 2000 milliseconds = 2 seconds, 10000 milliseconds = 10 seconds
 			 System.out.println("TcpExample4HandlerThread pausing for TIMEOUT=" + TIMEOUT + "ms"); // debug
              Thread.sleep(TIMEOUT); // 10 seconds
                 
-            ps.println("This was written by the server TcpExample4HandlerThread");
+            ps.println("This message was written by the server TcpExample4HandlerThread");
             ps.flush();
             socket.close();
             System.out.println("TcpExample4HandlerThread finished handling a thread, now exit.");
         }
         catch(IOException | InterruptedException e) // either a networking or a threading problem
         {
-            System.out.println("Problem with TcpExample4HandlerThread, see exception trace:");
-            System.out.println(e);
+            System.out.println("Problem with TcpExample4HandlerThread networking:"); // describe what is happening
+            System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
         }
     }
 }

examples/src/TcpExamples/TcpExample4ThreadServer.java

@@ -34,8 +34,11 @@ public class TcpExample4ThreadServer {
         }
         catch(IOException e)
         {
-            System.out.println("Problem with TcpExample4ThreadServer, see exception trace:");
+            System.out.println("Problem with TcpExample4ThreadServer networking:"); // describe what is happening
             System.out.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.out.println("*** Be sure to stop any other running instances of programs using this port!");
         }
 		System.out.println("=============================================================");
     }