Thread: Can't Get Network I/O To Write And Read Properly...

when I try to transmit the beginning two pieces of data, it attempts to transmit the file itself

I can't understand how code you've written can do that.
If you don't read the file, then it won't be able to send it.
You must have a logic problem.

I see zero comments in your code so I can't tell you if it is doing what you want it to do or not.

Originally Posted by Norm

I can't understand how code you've written can do that.
If you don't read the file, then it won't be able to send it.
You must have a logic problem.

I see zero comments in your code so I can't tell you if it is doing what you want it to do or not.

Yeah sorry I really need to start using comments more....

I realized what was happening. The call for the socket to get an output stream for the file was overriding the previous PrintWriter output stream call so the InputStreamReader was trying to read an incoming file. I guess I was assuming everything would be in perfect synchronization....

I am rewriting the code to start a new socket on the same (original) server through some callable thread concurrency, transmit the file information, close the socket, restart the socket, and transmit the file.

I am using a superclass called FileServices that the HostFiles and ClientFiles extend from.... now I have a new question. If I call the superclass method using the super keyword, will it read the subclass instance variables that are currently set? Or will I get a bunch of NPEs....

If I call the superclass method using the super keyword, will it read the subclass instance variables that are currently set? Or will I get a bunch of NPEs

Write a simple short program, compile and execute it to test.
Let us know what happens.

Originally Posted by Norm

Write a simple short program, compile and execute it to test.
Let us know what happens.

Thanks for your help... already did that. Check the OP. I changed it. I really need help on this problem...

Does the buffered output stream have some kind of hard limit?

Are you trying to send binary data as text/Strings? Doesn't work.

Originally Posted by Norm

Are you trying to send binary data as text/Strings? Doesn't work.

No.....

Does file input stream followed by output stream read by an input stream and rewritten by a file output stream sound like that to you?

Have you read the code yet?

If it's of any use the InputStream always stops reading at byte 65,536 if the file is larger than that number. I don't know why. Using a BufferedInputStream yields the same result...

Originally Posted by Norm

Why did you ask this?

I've lost track of your current problem. Can you explain?

0xFFFF=65535

That's the limit for 2 unsigned bytes

Sorry... I keep on solving problems and running into new ones. Here is where I am at now.... and I don't think I can solve this one.

I tweeked the file receiving code so that it uses a loop rather than rely on the read(int,int,int) method that doesn't seem to work all that well... (it only read a small portion of the file;65,535 bytes to be exact)

The whole file is now read... but the problem arises after the file gets written. No program is able to read it... sure enough the files look different if you compare their raw coding in a text editor.

So, to clarify, I can't seem to WRITE the file data to a new file properly. Here is the method that receives the file data and is supposed to write it to a new file in the specified directory:

     	protected void receiveFile() throws IOException {
		byte[] bytes = new byte[fileBytes];
		in = sock.getInputStream();
		for(int i=0;i<=fileBytes;i++) {
			in.read(bytes);
		}
		fos = new FileOutputStream("/Datawire/"+fileName);
		buffout = new BufferedOutputStream(fos);
		buffout.write(bytes,0,fileBytes);
		buffout.flush();
		buffout.close();
	}

the files look different

Completely or just a few bytes?

Can you make a small executable program that demos the problem that we can test with?

Originally Posted by Norm

Completely or just a few bytes?

A lot. Do you want me to send you example files?

Originally Posted by Norm

Can you make a small executable program that demos the problem that we can test with?

I will try...

And if it is worth mentioning, the bad file writing only occurs above a certain size... I haven't determined a specific number yet, however. Possible it could be that magical 65535 byte amount.

@Norm Here is the test program I wrote. Try transferring any file larger than 64k and it will corrupt it...

SimpleServer Class:

[CODE]package betatesting;
 
/*------------------------------------------------------------
 * Issue Demonstration: Test Application build01 (Main-Class)
 */
 
import java.net.*;
import java.io.*;
import java.util.concurrent.*;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
/* The SimpleServer class generates a simple GUI so that we can utilize the convenience of the JFileChooser.
 * Once you choose the file, the inner class will be called to start the server.
 * The server will NOT use a loop to keep accepting new clients, so that you can test different files.
 */
 
public class SimpleServer implements ActionListener {
	JFrame frame;
	File selection;
	private ExecutorService thread = Executors.newFixedThreadPool(5);
 
	public static void main(String[] args) {
		new SimpleServer().gui();
	}
 
	public void gui() {
		//Setup a GUI
		frame = new JFrame("TestApp");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		JPanel panel = new JPanel();
		JButton b1 = new JButton("Choose");
		b1.addActionListener(this);
		panel.add(b1);
		frame.getContentPane().add(BorderLayout.CENTER,panel);
		frame.setSize(300,300);
		frame.setVisible(true);
	}
	//The action listener for the choose button...
	public void actionPerformed(ActionEvent e) {
		JFileChooser chooser = new JFileChooser("Choose A File");
		int value = chooser.showOpenDialog(frame);
		if(value == JFileChooser.APPROVE_OPTION) {
			selection = chooser.getSelectedFile();
			StartServer ss = new StartServer();
			ss.setFile(selection);
			//Call a thread to run the server while we go start the client...
			thread.execute(ss);
			//Start the client
			SimpleClient client = new SimpleClient();
			client.go();
		} 
	}
 
	//---------------------------------------------------------------------------
 
	class StartServer implements Runnable {
		ServerSocket server;
		Socket socket;
		File file;
		/* The server will wait for a client request, print the information and close the socket.
		 * It will then wait for a second request, on which it will transfer the file.
		 */
		public void setFile(File newFile) {
			file = newFile;
		}
		public void run() {
			try {
			server = new ServerSocket(7575);
			socket = server.accept();
			System.out.println("Beginning file trasnfer...");
			PrintWriter writer = new PrintWriter(socket.getOutputStream());
			writer.println(file.getName());
			writer.println(file.length());
			writer.flush();
			socket.close();
			socket = server.accept();
			byte[] bytes = new byte[(int)file.length()];
			FileInputStream fis = new FileInputStream(file);
			BufferedInputStream buffin = new BufferedInputStream(fis);
			buffin.read(bytes,0,bytes.length);
			OutputStream os = socket.getOutputStream();
			os.write(bytes,0,bytes.length);
			os.flush();
			socket.close();
			} catch(IOException e) {
				e.printStackTrace();
			}
		}
	}
}
[/CODE]

SimpleClient Class:

[CODE]package betatesting;
 
import java.io.*;
import java.net.*;
 
public class SimpleClient {
	Socket socket;
	String fileName;
	int fileBytes;
 
	public void go() {
		try {
			//Start a new socket to get the info
			socket = new Socket("127.0.0.1",7575);
			InputStreamReader isr = new InputStreamReader(socket.getInputStream());
			BufferedReader reader = new BufferedReader(isr);
			fileName = reader.readLine();
			fileBytes = Integer.parseInt(reader.readLine());
			socket.close();
			//Socket to handle file transfer
			socket = new Socket("127.0.0.1",7575);
			byte[] bytes = new byte[fileBytes];
			InputStream is = socket.getInputStream();
			for(int i=0;i<fileBytes;i++) {
				is.read(bytes);
			}
			//Stores the file in a new directory in your system's default directory
			File dir = new File("/TestApp");
		    if(!dir.exists()) {
				dir.mkdir();
			}
			FileOutputStream fos = new FileOutputStream("/TestApp/"+fileName);
			BufferedOutputStream bos = new BufferedOutputStream(fos);
			bos.write(bytes,0,bytes.length);
			bos.close();
			socket.close();
			System.out.println("Transfer Complete");
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}
[/CODE]

Your problem is in the read loop on the client. Change and add this to see what happens:

	    int nbrRd = is.read(bytes);            // get count of bytes read this call
            System.out.println("C nbrRd=" + nbrRd); // Show nbr bytes read

Originally Posted by Norm

Your problem is in the read loop on the client. Change and add this to see what happens:

	    int nbrRd = is.read(bytes);            // get count of bytes read this call
            System.out.println("C nbrRd=" + nbrRd); // Show nbr bytes read

It said 65536... yes. It didn't read all of it. Do you have any idea on how to change that?

Did you make the changes I suggested? What was printed out?

BTW Nice test program.
However I prefer one that works automatically without a GUI.
I added this:

   public static void main(String[] args) {
      File selection = new File("images/AreWeFriends.jpg");
    	ExecutorService thread = Executors.newFixedThreadPool(5);
 
   	StartServer ss = new StartServer();
   	ss.setFile(selection);
   	//Call a thread to run the server while we go start the client...
   	thread.execute(ss);
 
   	//Start the client
   	SimpleClient client = new SimpleClient();
   	client.go();
 
 
   }

And commented out the SimpleServer up to the StartServer class definition

Originally Posted by Norm

BTW Nice test program.
However I prefer one that works automatically without a GUI.
I added this:

   public static void main(String[] args) {
      File selection = new File("http://www.javaprogrammingforums.com/images/AreWeFriends.jpg");
    	ExecutorService thread = Executors.newFixedThreadPool(5);
 
   	StartServer ss = new StartServer();
   	ss.setFile(selection);
   	//Call a thread to run the server while we go start the client...
   	thread.execute(ss);
 
   	//Start the client
   	SimpleClient client = new SimpleClient();
   	client.go();
 
 
   }

And commented out the SimpleServer up to the StartServer class definition

Hey whatever you prefer. I only used the GUI for the benefit of JFileChooser since it makes it easier to test different files.

Yes I did make the changes you suggested. It printed out "65536"

I suggested: System.out.println("C nbrRd=" + nbrRd);
And you say it printed out: 65536
I don't see how that is possible. What else did it print out? Wasn't "C nbrRd=" there?

Could you post the full code for the loop where the client reads the data sent from the server.

I did realize, however, I should probably be using smaller chunks of read data rather than trying to store all of the file data in one stream. I'm having trouble making that work though...

Originally Posted by Norm

I suggested: System.out.println("C nbrRd=" + nbrRd);
And you say it printed out: 65536
I don't see how that is possible. What else did it print out? Wasn't "C nbrRd=" there?

Could you post the full code for the loop where the client reads the data sent from the server.

Yes yes yes... I just figured that was unimportant. Exactly, it printed "C nbrRd = 65536".

Full code for the test app or the actual program?

Wait... did you mean make the change on the original program?

The purpose of the changes: get the number of bytes read and print them out is to provide debug information about how your program is executing.
I was talking about the test program which I have a copy of. I was telling you what I did to find the problem. I was asking you to do the same thing so you could see what I saw.

Originally Posted by Norm

The purpose of the changes: get the number of bytes read and print them out is to provide debug information about how your program is executing.
I was talking about the test program which I have a copy of. I was telling you what I did to find the problem. I was asking you to do the same thing so you could see what I saw.

There is no loop existent in the client side of the test application. Could you specify which section you are referring to?