diff --git a/assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorCopyTcpExample1Telnet.java b/assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorTcpExample1Telnet.java
similarity index 85%
rename from assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorCopyTcpExample1Telnet.java
rename to assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorTcpExample1Telnet.java
index 1a85abb0931d94778ea70ae647ce1df1377e902d..ab8e1ff23b6adcd30f63084d2b543bc6d753da6e 100644
--- a/assignments/src/MV3500Cohort2019JulySeptember/homework1/BrutzmanRefactorCopyTcpExample1Telnet.java
+++ b/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!");
}
}
}
diff --git a/examples/src/TcpExamples/TcpExample1Telnet.java b/examples/src/TcpExamples/TcpExample1Telnet.java
index 373c0f58ebb4345af3c4dcdeb79f1206ffb11706..65afb1959f0a8ee33c81220916baa5921e3fe94c 100644
--- a/examples/src/TcpExamples/TcpExample1Telnet.java
+++ b/examples/src/TcpExamples/TcpExample1Telnet.java
@@ -64,7 +64,10 @@ public class TcpExample1Telnet
}
catch(IOException e)
{
- System.out.println("problem with networking: " + e);
+ System.out.println("*** Problem with 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!");
}
}
}
diff --git a/examples/src/TcpExamples/TcpExample2ConnectionCounting.java b/examples/src/TcpExamples/TcpExample2ConnectionCounting.java
index 897fe538f7ec8c0c03a63e75776d659decb76074..9ab0e481be1c5f78075e8fe99701b75bde161c91 100644
--- a/examples/src/TcpExamples/TcpExample2ConnectionCounting.java
+++ b/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.
@@ -84,6 +85,9 @@ public class TcpExample2ConnectionCounting
catch(IOException e)
{
System.out.println("problem with 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!");
}
}
}
diff --git a/examples/src/TcpExamples/TcpExample3Client.java b/examples/src/TcpExamples/TcpExample3Client.java
index 87e44dae4ce5de6b80532253e6d2c109ad20e121..422c16234c4c328c0c9688efbd8d0a647bb1af05 100644
--- a/examples/src/TcpExamples/TcpExample3Client.java
+++ b/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);
+ // 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");
diff --git a/examples/src/TcpExamples/TcpExample3Server.java b/examples/src/TcpExamples/TcpExample3Server.java
index eeccda6f4bb813ebb8c1296b6424a9837832bd9d..f6c15238289768e38cd48f737accf21f80286a44 100644
--- a/examples/src/TcpExamples/TcpExample3Server.java
+++ b/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) {
+ catch (IOException e)
+ {
System.out.println("problem with networking");
+ // 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!");
}
}
}
diff --git a/examples/src/TcpExamples/TcpExample4HandlerThread.java b/examples/src/TcpExamples/TcpExample4HandlerThread.java
index 3a14d484f4064c2ec5a8b23bf61f4eb4958bcaca..8b51079dbf7d80ba3b894a9159b69ae6de78a626 100644
--- a/examples/src/TcpExamples/TcpExample4HandlerThread.java
+++ b/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
@@ -45,7 +45,7 @@ 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