Lost data on socket connection!

Hi all,
I have opened a socket connection with another pc, I pass it some parameters and in case of error it send back to me a big number of informations. The problem is: some informations are lost, in particular the first that is "code error", are there some ways to catch all informations with nothing loss?
Thanks!!!

Yes, it is possible to use sockets without losing information. In fact, getting all information trough with no loss is the normal behavior of sockets, and the behavior you get must be because of errors in your code.

Similar Messages

Socket lost data

We have a socket connection and when reading a huge XML file, part of it is lost. No exceptions are thrown. only a few lines in the middle of the xml is lost. We use
InputStream in = socket.getInputStream();
BufferedReader dis = new BufferedReader(new InputStreamReader(in));
while ((s = dis.readLine()) != null) {
...... some lines are lost for a huge xml
Thanks
Jayaraman

TCP/IP does not lose data. Show us the sending code. It is London to a brick that you aren't checking the return value of a write call, and assuming that all the data got written.
EJP

Binary Socket Connection Interruption? bytes lost?

Hi,
I am starting with a short introduction: I am currently working on a project, which involves a server application written in .NET (C#) and a flash gui app as client (standalone flash player 10 [code is written in Actionscript 3.0]). The server constantly sends bitmaps to the client (up to 30fps). The connection is established using binary sockets and data ist streamed to avoid socket open/close/reconnection problems.
The bitmaps sent to the client are marked with begin- and end-tags. A length field was added as well, to optimise the following parsing process. The client buffers the received data up to the point where an end-tag is found. The client reassambles the bitmaps on the screen by parsing the current buffer. Parsing means looking for begin-tags and length fields and/or end-tags of pictures packages. The resulting bitmap data is copied into a byte array and will loaded into a movieclip using the flash.display.Loader class ( bytePictureLoader.loadBytes( byteArray ); ).
Basically looks/works like this:
[SERVER]--->[BEGIN-TAG][LENGTH][BITMAPDATA][END-TAG]-[BEGIN-TAG][LENGTH][BITMAPDATA][END-T AG]-...--->[CLIENT]
While testing, I found out that in some cases the data stream becomes currupted, i.e. data is lost and/or the transmittion is incomplete.
A good thing is that this error is reproducable.
It seems that as soon as the Flash Application Window is dragged (moved on Windows Desktop) the stream lacks data.
The same error occurs, if too much data is sent to the client. The results are performance problems, data loss and other strange effects. The more data is sent on the stream, the more data has to be parsed and the more data gets lost somehow. Sometimes this leads to a memory problem, because Begin- and End-Tags aren't transmitted correctly. In order to fix (counteract) that, I discard data as long as there is no Begin-tag found and the buffer is cleared when the size exceeds 1Mb.
It works so far, but the application lacks performance and stability.
I.e. If 20 bitmaps per second with 620x390px are sent to the client, the client only receives 16 to 17 bitmaps, if the application does nothing else.
If 30 bitmaps per second with 620x390px are sent to the client, the client only receives about 20 to 21 bitmaps.
I am wondering, if there is actually a better solution the solve this problem.
I am guessing that using actuall video streams would be better, then sending one bitmap at a time in a byte stream.
Is there a proper example on how to build a client app in flash to receive/parse a binary data stream??
Does anyone else has recognized the lost-data problem or the interruption of streams?? And is there a solution to this problem?
thanks a lot for your attention hope you can help me out here!
cu
Tobi

Hi Hakan,
thx, but this doesn't work. I think flash struggels with the amount of data to parse. I tested sending images twice, but now i receive only 9 to 12 bitmaps out of 25 bitmaps sent.
Strange thing is, the problem only occurs if the flash player is maximised. As soon as I minimize the flash player window, the parsing works fine, but the image is not being loaded. Guess that's a performance feature of the flash player to not render actuall screen elements as long as the windows window of the flash player is not visible.

I've lost my Iphone 4 and found it back. i am unable to restore data. if i connect to itunes its getting restarted again and again. what should i do???

i've lost my Iphone 4 and found it back. i am unable to restore data. if i connect to itunes its getting restarted again and again. what should I DO ??? TS KEEP ON RESTARTING ALL THE TIME

Hi there balaji007,
You may find the troubleshooting steps in the articles below helpful.
If you can't update or restore your iOS device
http://support.apple.com/kb/ht1808
iPhone: Hardware troubleshooting
http://support.apple.com/kb/ts2802
Will not turn on, will not turn on unless connected to power, or unexpected power off
Verify that the Sleep/Wake button functions. If it does not function, inspect it for signs of damage. If the button is damaged or is not functioning when pressed, seek service.
Check if a Liquid Contact Indicator (LCI) is activated or there are signs of corrosion. Learn about LCIs and corrosion.
Connect the iPhone to the iPhone's USB power adapter and let it charge for at least ten minutes.
After at least 30 minutes, if:
The home screen appears: The iPhone should be working. Update to the latest version of iOS if necessary. Continue charging it until it is completely charged and you see this battery icon in the upper-right corner of the screen . Then unplug the phone from power. If it immediately turns off, seek service.
The low-battery image appears, even after the phone has charged for at least 20 minutes: See "iPhone displays the low-battery image and is unresponsive" symptom in this article.
Something other than the Home screen or Low Battery image appears, continue with this article for further troubleshooting steps.
If the iPhone did not turn on, reset it while connected to the iPhone USB power adapter.
If the display turns on, go to step 4.
If the display remains black, go to next step.
Connect the iPhone to a computer and open iTunes. If iTunes recognizes the iPhone and indicates that it is in recovery mode, attempt to restore the iPhone. If the iPhone doesn't appear in iTunes or if you have difficulties in restoring the iPhone, see this article for further assistance.
If restoring the iPhone resolved the issue, go to step 4. If restoring the iPhone did not solve the issue, seek service.
Issue not resolved
My issue is still not resolved. What do I do next?
Contact Apple Support.
-Griff W.

Lost data connectivity after upgrading iPhone 4 to iOS 5. How to fix?

Hello,
I upgraded my 16GB iPhone 4 yesterday from iOS 4.3.5 to iOS 5 and everything went fine after a few failed connections to Apple's servers, however my phone lost the data connectivity completely. Phone and SMS worked fine, I could also connect through wi-fi with no problems, however whenever I tried to use data I got a message that my phone was not signed to an internet service.
I restored my phone from the backup after upgrading. Not successful. I also reset the network configurations. No deal.
My carrier is Vivo (Brazil) and everything worked fine prior to the upgrade (and after the downgrade).
I imagine it can be a problem with APN configuration under iOS 5 and I tried to configure it through a webpage, but I got a message that my phone already had a APN config (profile) and could not install another. Under Settings>General>Network I don't have the "mobile network option" nor the "profile" option.
Any thoughts? So far I haven't contacted other people under my carrier who upgraded to see if they had the same problem.
Thanks for reading,
Samuel

I got a workaround; it's not what I wanted, but it solves the main problem.
I noticed that I only lost data connectivity after restoring from backup after the iOS 5 update. So what I did was to backup my phone, restore again to iOS 5, configure as a new phone and backup again (with nothing in the phone).
Then I launched an iPhone backup utility software, in this case, iBackupBot, which in the trial version is enough for what I wanted. I opened the old backup and exported only the files I wanted (like call history and SMS history), then I imported these files into the new backup and restored from it.
I lost my media files (which I copied before) and some configurations, but the most important itens, like SMS, I managed to export from the old (complete) backup.
Message was edited by: samuelsam

Is there any way to identify the particular socket connection is closed ?

Is there any way to identify the particular socket connection is closed or not ?
Any methods ???
How can the program knows the connection is lost or some thing ...
Is the socket throws some excpetions when there is no active connection ???
namanc

If you get an IOException when you try to use the socket, the connection was obviously closed.
The correct way for an application to know if the socket was closed is:
1) the server sends a message indicating that the socket should be closed
2) the client closes the socket itself

I suppose it is the problem with socket connection,Please help

Hi,
I'm trying to build a chat server in Java on Linux OS.I've created basically 2 classes in the client program.The first one shows the login window.When we enter the Login ID & password & click on the ok button,the data is sent to the server for verification.If the login is true,the second class is invoked,which displays the messenger window.This class again access the server
for collecting the IDs of the online persons.But this statement which reads from the server causes an exception in the program.If we invoke the second class independently(ie not from 1st class) then there is no problem & the required data is read from the server.Can anyone please help me in getting this program right.I'm working on a p4 machine with JDK1.4.
The Exceptions caused are given below
java.net.SocketException: Connection reset by peer: Connection reset by peer
at java.net.SocketInputStream.SocketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:119)
     at java.io.InputStreamReader$CharsetFiller.readBytes(InputStreanReader.java :339)
     at java.io.InputStreamReader$CharsetFiller.fill(InputStreamReader.java:374)
     at java.io.InputStreamReader.read(InputStreamReader.java:511)
     at java.io.BufferedReader.fill(BufferedReader.java:139)
     at java.io.BufferedReader.readLine(BufferedReader.java:299)
     at java.io.BufferedReader.readLine(BufferedReader.java:362)
     at Login.LoginData(Login.java:330)
     at Login.test(Login.java:155)
     at Login$Buttonhandler.actionPerformed(Login.java:138)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1722)
     at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:17775)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:4141)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:253)
     at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:261)
     at java.awt.Component.processMouseEvent(Component.java:4906)
     at java.awt.Component.processEvent(component.java:4732)
     at java.awt.Container.processEvent(Container.java:1337)
     at java.awt.component.dispatchEventImpl(Component.java:3476)
     at java.awt.Container.dispatchEventImpl(Container.java:1399)
     at java.awt.Component.dispatchEvent(Component.java:3343)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3302)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3014)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2967)
     at java.awt.Container.dispatchEventImpl(Container.java:1373)
     at java.awt.window.dispatchEventImpl(Window.java:1459)
     at java.awt.Component.dispatchEvent(Component.java:3343)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:439)
     at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:150)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:131)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
     My program looks somewhat like this :
1st class definition:
public class Login extends Jframe// Login is the name of the first class;
Socket connection;
DataOutputStream outStream;
BufferedReader inStream;
Frame is set up here
public class Buttonhandler implements ActionListener
public void actionPerformed(ActionEvent e) {
String comm = e.getActionCommand();
if(comm.equals("ok")) {
check=LoginCheck(ID,paswd);
test();
public void test() //checks whether the login is true
if(check)
new Messenger(ID);// the second class is invoked
public boolean LoginCheck(String user,String passwd)
//Enter the Server's IP & port below
String destination="localhost";
int port=1234;
try
connection=new Socket(destination,port);
}catch (UnknownHostException ex){
error("Unknown host");
catch (IOException ex){
ex.printStackTrace ();
error("IO error creating socket ");
try{
inStream = new BufferedReader(new InputStreamReader(connection.getInputStream()));
outStream=new DataOutputStream(connection.getOutputStream());
}catch (IOException ex){
error("IO error getting streams");
ex.printStackTrace();
System.out.println("connected to "+destination+" at port "+port+".");
BufferedReader keyboardInput=new BufferedReader(new InputStreamReader(System.in));
String receive=new String();
try{
receive=inStream.readLine();
}catch(IOException ex){ error("Error reading from server");}
if(receive.equals("Logintrue"))
check=true;
else
check=false;
try{
inStream.close();
outStream.close();
connection.close();
}catch (IOException ex){
error("IO error closing socket");
return(check);
// second class is defined below
public class Messenger
Socket connect;
DataOutputStream outStr;
BufferedReader inStr;
public static void main(String args[])
{ Messenger mes = new Messenger(args[0]);}
Messenger(String strg)
CreateWindow();
setupEvents();
LoginData(strg);
fram.show();
void setupEvents()
fram.addWindowListener(new WindowHandler());
login.addActionListener(new MenuItemHandler());
quit.addActionListener(new MenuItemHandler());
button.addActionListener(new Buttonhandle());
public void LoginData(String name)
//Enter the Server's IP & port below
String dest="localhost";
int port=1234;
int r=0;
String str[]=new String[40];
try
connect=new Socket(dest,port);
}catch (UnknownHostException ex){
error("Unknown host");
catch (IOException ex){
ex.printStackTrace ();
error("IO error creating socket ");
try{
inStr = new BufferedReader(new InputStreamReader(connect.getInputStream()));
outStr=new DataOutputStream(connect.getOutputStream());
}catch (IOException ex){
error("IO error getting streams");
ex.printStackTrace();
String codeln=new String("\n");
try{
outStr.flush();
outStr.writeBytes("!@*&!@#$%^");//code for sending logged in users
outStr.writeBytes(codeln);
outStr.write(13);
outStr.flush();
String check="qkpltx";
String receive=new String();
try{
while((receive=inStr.readLine())!=null) //the statement that causes the exception
if(receive.equals(check))
break;
else
     str[r]=receive;
     r++;
}catch(IOException ex){ex.printStackTrace();error("Error reading from socket");}
catch(NullPointerException ex){ex.printStackTrace();}
} catch (IOException ex){ex.printStackTrace();
error("Error reading from keyboard or socket ");
try{
inStr.close();
outStr.close();
connect.close();
}catch (IOException ex){
error("IO error closing socket");
for(int l=0,k=1;l<r;l=l+2,k++)
if(!(str[l].equals(name)))
stud[k]=" "+str[l];
else
k--;
public class Buttonhandle implements ActionListener
public void actionPerformed(ActionEvent e) {
//chat with the selected user;
public class MenuItemHandler implements ActionListener
public void actionPerformed(ActionEvent e)
String cmd=e.getActionCommand();
if(cmd.equals("Disconnect"))
//Disconnect from the server
else if(cmd.equals("Change User"))
     //Disconnect from the server & call the login window
else if(cmd.equals("View Connection Details"))
//show connection details;
public class WindowHandler extends WindowAdapter
public void windowClosing(WindowEvent e){
//Disconnect from server & then exit;
System.exit(0);}
I�ll be very thankful if anyone corrects the mistake for me.Please help.

You're connecting to the server twice. After you've successfully logged in, pass the Socket to the Messenger class.
public class Messenger {
    Socket connect;
    public static void main(String args[]) {
        Messenger mes = new Messenger(args[0]);
    Messenger(Socket s, String strg) {
        this.connect = s;
        CreateWindow();
        setupEvents();
        LoginData(strg);
        fram.show();
}

Problem with socket connection

have my gps reciver connected to the usb port - i have a daemon gpsd running which makes data available on tcp port 2947 for querying. when i do telnet, it gives proper data.
but when i open a socket connection using java, it does not print anything as output. actually telnet asks for an escape charatcer so i am sending "r" initially to the server but still the program does not print anything as output.
here is my java code -
import java.io.*;
import java.net.Socket;
public class test2
public static void main(String[] args)
try
Socket s = new Socket("localhost",2947);
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
s.getOutputStream())),true);
out.println("r");
BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
String line;
while(true)
line = in.readLine();
System.out.println(line);
catch (Exception e)
or sometimes it even shows error as
Exception in thread "main" java.net.SocketException: Invalid argument or cannot assign requested address
at java.net.PlainSocketImpl.socketConnect(Native Method)
and this is the output which i get on telnet -
ot@localhost ~]# telnet localhost 2947
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
r
GPSD,R=1
$GPRMC,000212,V,18000.0000,N,00000.0000,W,0.0000,180.000,101102,,*1A
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$PGRME,400.00,0.00,0.00*7B
$GPRMC,000213,V,18000.0000,N,00000.0000,W,0.0000,180.000,101102,,*1B
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$PGRME,400.00,0.00,0.00*7B
$GPRMC,000214,V,18000.0000,N,00000.0000,W,0.0000,180.000,101102,,*1C
$GPGSA,A,1,,,,,,,,,,,,,,,,*32

Actually the problem does not seem to be in the code because i tried some basic client server programs (without any gpsd etc in picture) and even they are not working in linux though they work perfectly in windows (on the same machine). In linux it shows exception
My socket programs dont work in linux it shows error -
ot@localhost winc]# java parser
Exception in thread "main" java.net.SocketException: Invalid argument or cannot assign requested address
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:305)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:171)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:158)
at java.net.Socket.connect(Socket.java:452)
at java.net.Socket.connect(Socket.java:402)
at java.net.Socket.<init>(Socket.java:309)
at java.net.Socket.<init>(Socket.java:124)
at parser.main(parser.java:10)
i have removed the firewall settings etc and it still doesnot work in linux
what could be the cause for this?
Sowmya

NIO Socket implementation - delay between select and get data from socket

Hi all,
I have implemented a internal CallAPI for RPC over a socket connection. It works fine but if there are more than five clients and some load I have the phenomena that the READ selector returns a SelectorKey but I did not get any data from the socket.
My implementation is based on NIO has following components:
+ Accept-Thread
Thread handles new clients.
+ Read-Thread
Thread handles the data from the socket for the registered client. Each request is handled in an own Process-Thread. A Thread-Pool implementation is used for processing.
+ Process-Thread
The Process-Thread reads the data from the socket and starts the processing of the logical request.
In my tests I get the notification of data at the socket. The Process-Thread want to read the data for the socket, but no data are available. In some situations if have to read about 20 times and more to get the data. Between each read attempt I have inserted a sleep in the Process-Thread if no data was available. This have improved the problem, but it already exists. I tested the problem with several systems and jvm's but it seams that it is independent from the system.
What can I to do improve the situation?
I already include the read implementation from the grizzly-Framework. But it doesn't improve the situation.
Socket - Init
     protected void openSocket( String host, int port ) throws IOException
          serverChannel = ServerSocketChannel.open();
          serverChannel.configureBlocking( false );
          serverSocket = serverChannel.socket();
          serverSocket.setReuseAddress( true );
          this.serverhost = host;
          this.serverport = port;
          this.srvAcceptSelector = Selector.open();
          this.srvReadSelector = Selector.open();
          InetSocketAddress isa = null;
          if ( serverhost != null )
               isa = new InetSocketAddress( this.serverhost, this.serverport );
          else
               isa = new InetSocketAddress( this.serverport );
          serverSocket.bind( isa, 50 );
          serverChannel.register( this.srvAcceptSelector, SelectionKey.OP_ACCEPT );
     }New Client � Init
     // New Client
     if ( key.isAcceptable())
          keyCountConnect++;
          ServerSocketChannel actChannel =
               (ServerSocketChannel) key.channel();
          // Socket akteptieren
          SocketChannel actSocket = actChannel.accept();
          if ( actSocket != null )
               actSocket.finishConnect();
               actSocket.configureBlocking( false );
               actSocket.socket().setTcpNoDelay( true );
               this.registerSocketList.add( actSocket );
               this.srvReadSelector.wakeup();
     }Read Data from Socket
    protected int readDatafromSocket( ByteArrayOutputStream socketdata )
         throws IOException
         int readedChars = 0;
        int count = -1;
        Selector readSelector = null;
        SelectionKey tmpKey = null;
        if ( sc.isOpen())
              ByteBuffer inputbuffer = null;
             try
                  inputbuffer = bufferpool.getBuffer();
                  while (( count = sc.read( inputbuffer )) > 0 )
                       readedChars += count;
                      inputbuffer.flip();
                       byte[] tmparray=new byte[inputbuffer.remaining()];
                       inputbuffer.get( tmparray );
                       socketdata.write( tmparray );
                      inputbuffer.clear();
                  if ( count < 0 )
                       this.closeSocket();
                       if( readedChars == 0 )
                            readedChars = -1;
                       if ( log.isDebug())
                              log.debug( "Socket is closed! " );
                  else if ( readedChars == 0 )
                       if ( log.isDebug())
                              log.debug( "Reread with TmpSelector" );
                       // Glassfish/Grizzly-Implementation
                     readSelector = SelectorFactory.getSelector();
                     if ( readSelector == null )
                          return 0;
                      count = 1;
                      tmpKey = this.sc.register( readSelector, SelectionKey.OP_READ );
                     tmpKey.interestOps(
                          tmpKey.interestOps() | SelectionKey.OP_READ );
                     int code = readSelector.select( 500 );
                     tmpKey.interestOps(
                         tmpKey.interestOps() & ( ~SelectionKey.OP_READ ));
                     if ( code == 0 )
                         return 0;
                         // Return on the main Selector and try again.
                       while (( count = sc.read( inputbuffer )) > 0 )
                            readedChars += count;
                           inputbuffer.flip();
                            byte[] tmparray=new byte[inputbuffer.remaining()];
                            inputbuffer.get( tmparray );
                            socketdata.write( tmparray );
                           inputbuffer.clear();
                       if ( count < 0 )
                            this.closeSocket();
                            if( readedChars == 0 )
                                 readedChars =-1;
                       else if ( count == 0 )
                              // No data
             finally
                  if ( inputbuffer != null )
                       bufferpool.releaseBuffer( inputbuffer );
                       inputbuffer = null;
                  // Glassfish-Implementierung
                if ( tmpKey != null )
                    tmpKey.cancel();
                if ( readSelector != null)
                    // Bug 6403933
                     try
                        readSelector.selectNow();
                     catch (IOException ex)
                    SelectorFactory.returnSelector( readSelector );
        return readedChars;
    }Thanks for your time.

I've commented on that blog before. It is rubbish:
- what does 'overloading the main Selector' actually mean? if anything?
- 'Although this not clearly stated inside the NIO API documentation': The API documentation doesn't say anything about which Selector you should register channels with. Why would it? Register it with any Selector you like ...
- 'the cost of maintaining multiple Selectors can reduce scalability instead of improving it' Exactly. So what is the point again?
- 'wrapping a ByteBuffer inside a ByteBufferInputStream:' Code is rubbish and redundant. java.nio.channels.Channels has methods for this.
There is no a priori advantage to using multiple Selectors and threads unless you have multiple CPUs. And even then not much, as non-blocking reads and writes don't consume significant amounts of CPU. It's the processing of the data once you've got it that takes the CPU, and that should be done in a separate thread.
So I would re-evaluate your strategy. I suspect you're getting the channel registered with more than one Selector at a time. Implement it the simple way first then see if you really have a problem with 'overloading the main Selector' ...

How to make a socket connection timeout infinity in Servlet doPost method.

I want to redirect my System.out to a file on a remote server (running Apache Web Server and Apache Tomcat). For which I have created a file upload servlet.
The connection is established only once with the servlet and the System.out is redirected to it. Everything goes fine if i keep sending data every 10 second.
But it is required that the data can be sent to the servlet even after 1 or 2 days. The connection should remain open. I am getting java.net.SocketTimeoutException: Read timed out Exception as the socket timeout occurs.
Can anyone guide me how to change the default timeout of the socket connection in my servlet class.
Following is the coding to establish a connection with the Servlet.
URL servletURL = new URL(mURL.getProtocol(), mURL.getHost(), port, getFileUploadServletName() );
URLConnection mCon = servletURL.openConnection();
mCon.setDoInput(true);
mCon.setDoOutput(true);
mCon.setUseCaches(false);
mCon.setRequestProperty("Content-Type", "multipart/form-data");
In the Servlet Code I am just trying to read the input from the in that is the input stream.
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
BufferedInputStream in = new BufferedInputStream(req.getInputStream());
byte [] content = new byte[1024];
do
read = in.read(content, 0, content.length);
if (read > 0)
out.write(content, 0, read);
I have redirected the System.out to the required position.
System.setOut(........);
Can anyone guide me how to change the default timeout of the socket connection in my servlet class.

I am aware of the setKeepAlive() method, but this can only used with the sockets. Here i am inside a servlet, have access to HTTPServletRequest and HTTPServletResponse and I don't know how to get access to the underlying sockets as the socket handling will be handled by the tomcat itself. If I am right there will be method in the apache tomcat 6.0.x to set this property. But till now I am not getting it.

Multiple clients on socket connection

Hi!
I understand that it is possible that multiple clients listen to one server (on the same port) and even write to it (then it should be a multi-threaded server).
But i would like to refuse connectios, if one client is connected. How can I do that?
In my case I have a (single threaded) server. Now one clients connects. The server waits to receive data from the client and answers, without ever closing the port. that works.
Now if I connect with a second client, the openicng of the socket in the second client works fine, although the server does not seem to notice the second client. Communication is not possible between the server and the second client, and the server doesn't answer to the first client anymore, although he receives data from it.
So, since the server does not seem to notice the second client (does not accept the connection) and I don't get an exception at the second client, what can I do?
Thank you for your help!
concerned Code (if you want to take a look at it):
CLIENT:
socket = new Socket(hostname, echo_port);
SERVER:
try
ServerSocket waitingsocket = new ServerSocket(echo_port);
try
     socket= waitingsocket.accept();
     System.out.println("Client connected");
     ReaderThread reader = new ReaderThread( this, socket );
     reader.start();
catch (Exception e)
READER:
public void run()
     while (true)
          try {
               int bytesRead = inStream.read(inputBuffer,
               0, inputBuffer.length);
               readCallback.tcpUpdate(inputBuffer,bytesRead);
          catch (Exception oops)
               readCallback.tcpUpdate(null,-1);


Just to make sure this is clear: You can NOT have multiple clients on a given socket connection. You CAN have multiple clients connected to a particular port on a given server, but each client will be communicating with the server through a different of socket.
The usual approach here is to set up a listening ServerSocket on the desired port, call accept() on it, then process the communication from the returned Socket object. This is usually done by spawning a new thread and allowing it to handle the socket communication, while the ServerSocket loops around to another accept() for the next communication.
Here's an excellent intro to the concepts (the code is really ugly and poorly implemented, but it does a good job of explaining the overall concept). I used this as a starting point, and now (after a whole lot of development) have a pretty sweet extensible web server class that handles template expansion, etc... (I use this as a quick and dirty UI for some of my apps, instead of requiring the user to install a JSP container):
http://developer.java.sun.com/developer/technicalArticles/Networking/Webserver/
- K

How can i reuse my existing socket connection

Hi,
this might sound basic, it probably is:
As part of my larger project, i have to send and recieve data to multiple socket connections.
The thing that happens is that everytime i send data, it seems that java is creating a new stream or something (code is multithreaded)
so as i send 4 items of data, a bit like a chat program sending 4 statements, it creates 4 different streams, instead of using the same stream. therefore when i close the connection, i get:
java.net.SocketException: Connection reset 4 times.
i know why.. its because i have added the:
Socket socket=new Socket(host, port);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
bit in the same method with the
out.println(THE DATA....);
out.flush();
The thing what i want to do is to create the connection one, and reuse the objects:
out, in and socket
to send / recieve the new data.
please help me guys,
thanks

All the threads would be able to get the same reference to....
class SocketWrapper {
     private final Object readLock = new Object();
     private final Object writeLock = new Object();
     // client side
    public SocketWrapper(String hostname, int port);
     // server side.
    public SocketWrapper(Socket);
     // send data
     public void send(Serializable object) throws IOException;
     // receive data. synchronized(writeLock);
     public Serializable getNext() throws IOException;
     // create a new socket as required, throw IllegalState if server side. synchronized(readLock)
     private void createNewSocket() throws IllegalStateException;
}The send autoconnects as required. It then send on message/packet/object.
The getNext autoconnects as required. It reads one message/packet/object and returns.
This allows multiple threads to access the same socket. It allows data to be sent while a thread is blocking on a read. (Thus two locks)

How can i create a socket connection through an http proxy

i'm trying to make a socket connection send an email - i have code that works when you don't have to go through a proxy server but i can't make it pass the proxy server.
import java.net.*;
import java.io.*;
import java.util.*;
public class Mail
public String to_address = "[email protected]";
public String from_address = "[email protected]";
public String sendSub = "HeHeHe";
public String sendBody = "hehehe - it worked";
// This is created to allow data to be read in by the keyboard.
BufferedReader in = new BufferedReader(
new InputStreamReader(System.in));
     private void Mail(String to_address, // recipient's addresses
String from_address, // sender's address
String sendSub, // subject
String sendBody) // Message
               throws IOException, ProtocolException,      UnknownHostException {
     Socket socket;                // creates a Socket named socket
     PrintStream out;               // stream to write to socket
     String host = "imap.btopenworld.com";          // identification of the mail server host
// creates a new socket for connection to the mail server
// as well as two variables for the read and write streams
     socket = new Socket(host, 25); // opens socket to host on port 25 (SMTP port)
     out = new PrintStream(socket.getOutputStream());
// read the initial message
     in.readLine();
// Dialog with the mail server
// send HELO to SMTP server HELO command is given by a connecting SMTP host
     out.println( "HELO " + host );
     out.flush() ;
     in.readLine();
// Once we are connected to the mail server we start sending the email...
// send "from"
     out.println( "MAIL FROM: " + from_address );
     out.flush() ;
     in.readLine();
// send "to"
     out.println( "RCPT TO: " + to_address );
     out.flush() ;
     in.readLine();
// prepare the mailserver to receive the data
     out.println( "DATA" );
     out.flush() ;
     in.readLine();
// Send actual email
     out.println("From: " + from_address);
     out.println("To: " + to_address);
     out.println( "Subject: " + sendSub + "\n" );
     out.flush() ;
     out.println("");
     out.println( sendBody ) ;
     out.println(".") ; // standard to determine end-of-body
     out.flush() ;
     in.readLine();
//Quit and closes socket
     out.println("QUIT");
     out.flush();
     in.close() ;
     socket.close() ;
     return ;
public static void main (String [] args) throws IOException
Mail themail = new Mail();
}

i've tried that but it doesn't seem to do nething - this is how i implemented it...
import java.net.*;
import java.io.*;
import java.util.*;
public class Mail
public String to_address = "[email protected]";
public String from_address = "[email protected]";
public String sendSub = "HeHeHe";
public String sendBody = "hehehe - it worked";
// This is created to allow data to be read in by the keyboard.
BufferedReader in = new BufferedReader(
new InputStreamReader(System.in));
     private void Mail(String to_address, // recipient's addresses
String from_address, // sender's address
String sendSub, // subject
String sendBody) // Message
               throws IOException, ProtocolException,      UnknownHostException {
     Socket socket;                // creates a Socket named socket
     PrintStream out;               // stream to write to socket
     String host = "imap.btopenworld.com";          // identification of the mail server host
// creates a new socket for connection to the mail server
// as well as two variables for the read and write streams
     socket = new Socket(host, 25); // opens socket to host on port 25 (SMTP port)
     out = new PrintStream(socket.getOutputStream());
// read the initial message
     in.readLine();
System.getProperties().put( "proxySet", "true" );
          System.getProperties().put( "proxyHost", "144.124.16.28" );
          System.getProperties().put( "proxyPort", "8080" );
// Dialog with the mail server
// send HELO to SMTP server HELO command is given by a connecting SMTP host
     out.println( "HELO " + host );
     out.flush() ;
     in.readLine();
// Once we are connected to the mail server we start sending the email...
// send "from"
     out.println( "MAIL FROM: " + from_address );
     out.flush() ;
     in.readLine();
// send "to"
     out.println( "RCPT TO: " + to_address );
     out.flush() ;
     in.readLine();
// prepare the mailserver to receive the data
     out.println( "DATA" );
     out.flush() ;
     in.readLine();
// Send actual email
     out.println("From: " + from_address);
     out.println("To: " + to_address);
     out.println( "Subject: " + sendSub + "\n" );
     out.flush() ;
     out.println("");
     out.println( sendBody ) ;
     out.println(".") ; // standard to determine end-of-body
     out.flush() ;
     in.readLine();
//Quit and closes socket
     out.println("QUIT");
     out.flush();
     in.close() ;
     socket.close() ;
     return ;
public static void main (String [] args) throws IOException
Mail themail = new Mail();
}

Establishing a socket connection between a .swf file and a socket-test program (TCP/IP builder - Windows), in AS3.

I have an issue with a college project I'm working on.
Using Actionscript 3, I made a simple .swf program, an animated, interactive smiley, that 'reacts' to number inputs in a input-box.
For the sake of the project, I now need to make the framework for establishing a socket connection with the smiley .swf, and another program.
This is where I encounter issues. I have very little knowledge of AS3 programming, so I'm not certain how to establish the connection - what's required code-wise for it, that is.
To test the connection, I'm attempting to use the "TCP/IP builder" program from windows, which lets me set up a server socket. I need to program the .swf file into a client - to recognize it, connect to it, then be able to receive data (so that the data can then be used to have the smiley 'react' to it - like how it does now with the input-box, only 'automatically' as it gets the data rather than by manual input).
My attempts at coding it are as follows, using a tutorial (linked HERE):
//SOCKET STUFF GOES HERE
    var socket:XMLSocket;
    stage.addEventListener(MouseEvent.CLICK, doConnect);
// This one connects to local, port 9001, and applies event listeners
    function doConnect(evt:MouseEvent):void
    stage.removeEventListener(MouseEvent.CLICK, doConnect);
    socket = new XMLSocket("127.0.0.1", 9001);
    socket.addEventListener(Event.CONNECT, onConnect);
    socket.addEventListener(IOErrorEvent.IO_ERROR, onError);
// This traces the connection (lets us see it happened, or failed)
    function onConnect(evt:Event):void
        trace("Connected");
        socket.removeEventListener(Event.CONNECT, onConnect);
        socket.removeEventListener(IOErrorEvent.IO_ERROR, onError);
        socket.addEventListener(DataEvent.DATA, onDataReceived);
        socket.addEventListener(Event.CLOSE, onSocketClose);
        stage.addEventListener(KeyboardEvent.KEY_UP, keyUp);
    function onError(evt:IOErrorEvent):void
        trace("Connect failed");
        socket.removeEventListener(Event.CONNECT, onConnect);
        socket.removeEventListener(IOErrorEvent.IO_ERROR, onError);
        stage.addEventListener(MouseEvent.CLICK, doConnect);
// Here, the flash tracks what keyboard button is pressed.
// If 'q' is pressed, the connection ends.
        function keyUp(evt:KeyboardEvent):void
        if (evt.keyCode == 81) // the key code for q is 81
            socket.send("exit");
        else
            socket.send(evt.keyCode);
// This one should handle the data we get from the server.
        function onDataReceived(evt:DataEvent):void
        try {
            trace("From Server:", evt.data );
        catch (e:Error) {
            trace('error');
    function onSocketClose(evt:Event):void
        trace("Connection Closed");
        stage.removeEventListener(KeyboardEvent.KEY_UP, keyUp);
        socket.removeEventListener(Event.CLOSE, onSocketClose);
        socket.removeEventListener(DataEvent.DATA, onDataReceived);
Trying to connect to the socket gives me either no result (other than a 'connection failed' message when I click the .swf), or the following error:
Error #2044: Unhandled securityError:. text=Error #2048: Security sandbox violation: file:///C|/Users/Marko/Desktop/Završni/Flash%20documents/Smiley%5FTCP%5FIP%5Fv4.swf cannot load data from 127.0.0.1:9001.
    at Smiley_TCP_IP_v4_fla::MainTimeline/doConnect()[Smiley_TCP_IP_v4_fla.MainTimeline::frame1:12]

Tried adding that particular integer code, ended up with either errors ("use of unspecified variable" and "implicit coercion") , or no effect whatsoever (despite tracing it).
Noticed as well that the earlier socket code had the following for byte reading:
"sock.bytesAvailable > 0" (reads any positive number)
...rather than your new:
"sock.bytesAvailable != 0" (reads any negative/positive number)
Any difference as far as stability/avoiding bugs goes?
So then, I tried something different: Have the program turn the "msg" string variable, into a "sentnumber" number variable. This seemed to work nicely, tracing a NaN for text (expected), or tracing the number of an actual number.
I also did a few alterations to the input box - it now no longer needs the 'enter' key to do the calculation, it updates the animation after any key release.
With all this considered and the requirements of the project, I now have a few goals I want to achieve for the client, in the following order of priority:
1) Have the "sentnumber" number variable be recognized by the inputbox layer, so that it puts it into the input box. So in effect, it goes: Connect -> Send data that is number (NaN's ignored) -> number put into input box -> key press on client makes animation react. I optionally might need a way to limit the number of digits that the animation reacts to (right now it uses 1-3 digit numbers, so if I get sent a huge number, it might cause issues).
- If the NaN can't be ignored (breaks the math/calculus code or some other crash), I need some way of 'restricting' the data it reads to not include NaN's that might be sent.
- Or for simplicity, should I just detect the traced "NaN" output, reacting by setting the number variable to be "0" in such cases?
2) After achieving 1), I'll need to have the process be automatic - not requiring a keyboard presses from the client, but happening instantly once the data is sent during a working connection.
- Can this be done by copying the huge amounts of math/calculus code from the inputbox layer, into the socket layer, right under where I create the "sentnumber" variable, and modifying it delicately?
3) The connection still has some usability and user issues - since the connection happens only once, on frame 1, it only connects if I already have a listening server when I run the client, and client can't re-connect if the server socket doesn't restart itself.
I believe to do this, I need to make the connection happen on demand, rather than once at the start.
For the project's requirement, I also need to allow client users to define the IP / port it's going to connect to (since the only alternative so far is editing the client in flash pro).
In other words, I need to make a "Connect" button and two textboxes (for IP and port, respectively), which do the following:
- On pressing "Connect", the button sets whatever is in the text boxes as the address of the IP and port the socket will connect to, then connects to that address without issues (or with a error message if it can't due to wrong IP/port).
- The connection needs to work for non-local addresses. Not sure if it can yet.
- On re-pressing connect, the previous socket is closed, then creates a new socket (with new IP/port, if that was altered)
It seems like making the button should be as simple as putting the existing socket code under the function of a button, but it also seems like it's going to cause issues similar to the 'looping frames' error.
4) Optional addition: Have a scrolling textbox like the AIR server has, to track what the connection is doing on-the-fly.
The end result would be a client that allows user to input IP/Port, connects on button press (optionally tracking/display what the socket is doing via scrollbox), automatically alters the smiley based on what numbers are sent whilst the connection lasts, and on subsequent button presses, makes a new connection after closing off the previous one.
Dropbox link to new client version:
https://www.dropbox.com/s/ybaa8zi4i6d7u6a/Smiley_TCP_IP_v7.fla?dl=0
So, starting from 1), can I, and how can I, get the number variable recognized by "inputbox" layer's code? It keeps giving me 'unrecognized variable' errors.

File Connection and Socket Connection in nokia 7710

Hello,
i want to transfer some data from my PC to Nokia 7710 either using File Transfer or socket connection
For file transfer, where do i need to put my file i.e. which files does nokia 7710 allow j2me programs to access? Is is ok if the file i transfer is a plain txt file? i am using jsr 75 api for reading from the file, so what file location will i give in my program, in Nokia 7710, there are two memory drives Device and Memory Stick, so how can i access these files via a j2me program running on the cell?
If i use socket connection, how will the phone recognize PC's ipaddress? Do i need to configure it? Also my Nokia 7710 is connected to the PC via a cable attached to USB port, so what port numbers do i specify in my j2me client program that will run on the phone and normal java server program that will run on the PC
please help me out, this is very important for me
thank you

Hi Steve, Would you mind to give a a piece of code to solve this problem
This is my code :
                          is = sc.openInputStream();
            os = sc.openOutputStream();
            os.write(("HELO there" + "\r\n").getBytes());
            os.write(("EHLO" + "\r\n").getBytes());
            os.write(("AUTH LOGIN" + "\r\n").getBytes());
            os.write(("dHVnYXNha2hpci50cmlhZGl0eWFAZ21haWwuY29t" + "\r\n").getBytes());
            os.write(("dGEuZW1haWxjbGllbnQ=" + "\r\n").getBytes());
            os.write(("MAIL FROM:<"+ from +">\r\n").getBytes());
            os.write(("RCPT TO:<"+ to + ">\r\n").getBytes());
            os.write("DATA\r\n".getBytes());
                   // stamp the msg with date
            os.write(("Date: " + new Date() + "\r\n").getBytes());
            os.write(("From: "+from+"\r\n").getBytes());
            os.write(("To: "+to+"\r\n").getBytes());
            os.write(("Subject: "+subject+"\r\n").getBytes());
            os.write((msg+"\r\n").getBytes()); // message body]
            os.write(".\r\n".getBytes());
            os.write("QUIT\r\n".getBytes());
                          StringBuffer sb = new StringBuffer();
                          int ch = 0;
            while((ch = is.read()) != -1) {
               sb.append((char) ch);
            si.setText("SMTP server response - " + sb.toString());but it doesn't work,...
i try to connect smtp gmail with smtp server : smtp.gmail.com and port : 465 (Use SSL)
regards
triaditya

Lost data on socket connection!

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