How to detact socket connection status

hi.. i am using socket class for the connection. How can I
detect for disconnection of the socket? Because calling the Flush()
method (called writeUTFBytes() eariler) is not throwing IOError
exception. I found that AIR has some network monitor which can be
used for this case. But I am not using AIR. Also, another work
around it to connect to some URL again to check the status. I don't
really want to use this method because the application needs to
send data back to the server very very often and I'd like to be
slow down. please help me out.....thanks in advance...

Hello Kent,
We can view active RFC Connections through SMGW. But if you want to have the history of the login details I guess you need to activate Logging.
SMGW -> Goto Expert Functions -> Logging -> Select appropiate options.

Similar Messages

How to retain socket connection for multiple requests in java 1.3

Hi All,
My problem is to retain client socket connection without opening and closing socket connection for every request.I want to open the socket connection once and send multiple requests one after the other based upon the response over the same socket.Finally I want to close the socket only after completing all my requests and receiving respective responses.I don't want to open and close the socket for each request and response.While at the same time I expect the socket to send each request only after receiving the response for the previous request.
I am using java 1.3 and I am looking for the solution in same version.
Please help me .
Thanx in advance.

Look at my response to "Telnet to Unix box from Java"
http://forum.java.sun.com/thread.jsp?forum=31&thread=437231
on "Java Programming" forum. It does exactly that to run the signon and a command. It would be easy to extend it to do multiple commands.

How do I view connection status of attendees in version 9

I have tried Pod options but there is no option to view connection status as described in this article:http://www.connectusers.com/tutorials/2009/03/voip_best_practices/index.php

This feature was dropped in Connect 8. Since it only showed the selected level of connectivity for the users (LAN by default) it never really gave any valuable feedback about the actual connectivity level.

How to enable socket connection?

I have allowed INTERNET permission, but my socket still blocked.
     <uses-permission android:name="android.permission.INTERNET" />
If I compile apk with -debug tag, then socket connection works, but my application runs very slow.
And I dont want to publish a release version with all my debug messages.
What is the standard way to open socket connection?
Thanks

               var s:Socket=new Socket();
                s.connect("ip_address", "port_number");
                s.addEventListener(Event.CONNECT, function(event:Event):void{
                    trace('connected!');
                s.addEventListener(IOErrorEvent.IO_ERROR, function(event:IOErrorEvent):void{
                    trace('error! ' + event.errorID);
                s.addEventListener(ProgressEvent.SOCKET_DATA, function(event:ProgressEvent):void{
                    var str:String=(event.currentTarget as Socket).readUTF();
There are examples out there. Fire up Google Search .

Socket - Connection Status

How can one check for the status of a connection once the connection to the socket succeeded.
something like (pseudocode):
if (connection to socket is open) {
Do whatever;
Thank you very much in advance. A.

How can one check for the status of a connection once
the connection to the socket succeeded.
something like (pseudocode):
if (connection to socket is open) {
Do whatever;
Thank you very much in advance. A.Normally you don't check the status of the connection. Instead you use a try-catch block like this:
try
   Socket mySocket = new Socket(...
   whatever else here
catch (IOException ioe)
   here put code to handle the connection not succeding
catch (UnknownHostException uhe)
   here put code to handle this type of exception
}If the connection is not succesfull (for whatever reason) control will transfer to one or the other catch blocks.

How to establish socket Connection for Flash Game ;-)

Currently im working on casino game. i want to make it multiPlayer. need help to establish socket game connection

Look at my response to "Telnet to Unix box from Java"
http://forum.java.sun.com/thread.jsp?forum=31&thread=437231
on "Java Programming" forum. It does exactly that to run the signon and a command. It would be easy to extend it to do multiple commands.

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.

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();
}

TCP Socket connection in CLOSE_WAIT status and not getting closed

I am facing an issue with the TCP socket connections not getting closed and they are in CLOSE_WAIT status for ever.
As a part of batch process in our application, emails are sent with 4 embedded images. These images are downloaded from 3rd party site with IP say "UUU.XXX.YYY.ZZZ"
The images are embedded to email as follows
1. An URL object is created with the site url.
URL urlPhoto = new
URL("http://UUU.XXX.YYY.ZZZ/email/photos.jpg");
2.     The image cid is created with the URL object and the image name
HtmlEmail htmlEmail = new HtmlEmail();
String cid1 = htmlEmail.embed(urlPhoto,
"photo.jpg");
3.     The image cid is added to the email template by replacing the ${cid1} and the email is sent.
<td valign="top">
               <img src="cid:${cid1}" width="279" height="274">
          </td>
When a mail is sent, 4 new TCP connections are opened and are put in CLOSE_WAIT status for ever. For every mail sent 4 new connections are opened. In UNIX there is an upper limit on the number of open file handles (defaults to 1024) at any point of time. The open TCP connection has the underlying socket in CLOSE_WAIT status and is not getting closed at all. When the upper limit (1024) is reached the batch process is throwing the following exception and terminates.
Caused by: com.inet.tds.ap: java.net.SocketExceptionjava.net.SocketException: Too many open files
at com.inet.tds.am.a(Unknown Source)
at com.inet.tds.TdsDriver.a(Unknown Source)
at com.inet.tds.TdsDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:525)
at java.sql.DriverManager.getConnection(DriverManager.java:171)
at com.hcomemea.batchprocess.dataaccess.database.BaseJdbcDao.openConnection(BaseJdbcDao.java:106)
... 12 more
When I run the command lsof in UNIX which list the open file handles in the system
$ /usr/sbin/lsof -p 22933 -i | grep CLOSE_WAIT
java 22933 build_master 297u IPv6 129841943 TCP integration.com:47929->UUU.XXX.YYY.ZZZ:http (CLOSE_WAIT)
java 22933 build_master 298u IPv6 129841947 TCP integration.com:47933->UUU.XXX.YYY.ZZZ:http (CLOSE_WAIT)
java 22933 build_master 299u IPv6 129841950 TCP integration.com:47936->UUU.XXX.YYY.ZZZ:http (CLOSE_WAIT)
java 22933 build_master 300u IPv6 129841970 TCP integration.com:47952->UUU.XXX.YYY.ZZZ:http (CLOSE_WAIT)
��list of 935 connections similarly�
I tried 2 solutions
1. Got the HttpURLConnection from the URL object and invoked disconnect method on the same. But it doesn�t work.
2. Ran the batch process java program with the parameter �Dhttp.keepAlive=false to close the underlying connection but didn�t help.
I need the underlying sockets to be closed and not put in CLOSE_WAIT status after sending the mail.
Is it the problem with the embed method of HtmlEmail object not closing the underlying socket connection.
If anyone has faced this issue before, kindly let me know the possible solutions for the same ASAP.
Thank you,
Ramesh G

This sounds more like a problem due to connection pooling at middle tier/application server.
If that has been ruled out, then you might to enable DCD or set expiry time on the server.

How do I transfer files verbatim across a socket connection?

So, I've got this socket connection running between two computers. I want one computer to take a file (C:\SourceFile.doc for example) and transfer it verbatim over an Internet connection to another computer (C:\DestFile.doc for example). By verbatim, I mean bit for bit, no changes to the format. It would seem that a filereader/filewriter system would work, and it does fine for .txt or plain files, but if I try to do something fancy, like a Microsoft word document (.doc) it doesn't work. Specifically, it saves a bunch of garbage at the begging and end of the file. How do I correct this?
From my file transmitter:
out.println("Prepare for Text File");
FileReader localin = new FileReader(file);
int l=0;
while((l=localin.read())!=-1)
     //System.out.print((char)l);
     out.print((char)l);
localin.close();
out.println("End Of File");
From my file reciever
if(line.equals("Prepare for Text File"))
     System.out.println("ready for text");               if(fileChooser.showSaveDialog(RadioComReciever.this)==JFileChooser.APPROVE_OPTION)
File localFile=fileChooser.getSelectedFile();
          FileWriter localout = new FileWriter(localFile);
          line=in.readLine();
          while(!line.equals("End Of File"))
               for(int i=0;i<line.length();i++)
               {                                                                 localout.write((byte)line.charAt(i));
               localout.write('\n');
               System.out.println();
               line=in.readLine();
          localout.close();
Thanks for any help!

But my program is already accessing text from a
socket connection. Is there a way to transfer things
over sockets other than text?Yes. Everything that goes over a socket connection is bytes. Certainly you can transfer text, because it can be represented in bytes, but not all files are text. So just send the bytes as is.
Don't get me wrong, I'm thankful for you help, I just
thought scokets mostly transfered just text. Am I
wrong?I don't have any statistics on how much Internet traffic is text. But 100% of it is bytes. Just send the bytes as is.
And is it just me, or is the documentation on File
I/O provided by Sun somewhat lacking?It isn't the job of the documentation to explain basic Java concepts like the difference between byte and char. That's the job of the tutorials. Like the Java I/O tutorial.

How to change HttpURLConnection to socket connection in java

hello i have a problem about a socket connection can you help me
i want to change HttpURLConnection connection to socket connection
here is
          java.net.URL url = new java.net.URL("http://64.74.75.74/approot/webapp/ZOR/bare");
          connection = new sun.net.www.protocol.http.HttpURLConnection(url, " ", 0);
          connection.setRequestMethod("POST");
          connection.setDoInput(true);
          connection.setDoOutput(true);
          connection.setUseCaches(false);
          java.io.ObjectOutputStream out = new java.io.ObjectOutputStream(connection.getOutputStream());
          out.writeObject(getTextFieldGiden().getText());
          out.flush();
          out.close();
          return (String) (new java.io.ObjectInputStream(connection.getInputStream()).readObject());
how can i change it to
socket connection
thank you very much

The class you mention uses a Socket connection.
If you read the source you will see how it does it.
If you use a debugger yu will see the code which is most relevent.

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 to know if a socket connection is open ?

Hi,
I have a ftp class that opens a socket connection to a ftp server. Sometimes the connection is closed and I get an exception. There is any way to know if exists an open connection ?
Thanks !

From SDK v1.3.1 for abstract Class SocketImpl:
Method connect
protected abstract void connect(InetAddress address,
                                int port)
                         throws IOException
    Connects this socket to the specified port number on the specified host.
Parameters:
address - the IP address of the remote host.port - the port number.Throws:
IOException - if an I/O error occurs when attempting a connection.... So if it throws an exception on inception, it's NOT connected - NOT open, right? This is the class you've subclassed to create the socket connection? If not, which?

How to Create a Single Backend Socket connectivity in a Server Socket Pgm

Hi Everybody,
I have a written a Server Socket which connects to back end socket and receiving the data and sending back to the front end. But as per my client requirement i need to create only one socket at the back end. But the code I have written is creating new sockets for each request. Is there any way to use the single client socket connection for all the transactions. I have attached the sample code for the reference.
import java.io.*;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
public class serl implements Runnable
ServerSocket serversocket;
Socket clientsoc;
Socket fromclient;
PrintStream streamtoclient;
BufferedReader streamfromclient;
SocketChannel socket_channel=null;
Thread thread;
public serl()
try
serversocket = new ServerSocket(1001);//create socket
clientsoc = new Socket("10.100.53.145",200);
socket_channel = clientsoc.getChannel();
catch(Exception e)
System.out.println("Socket could not be created "+e);
thread=new Thread(this);
thread.start();
public void run()
try
while(true)
PrintStream streamtobackend=null;
BufferedReader streamfrombackend = null;
fromclient=serversocket.accept();//accept connection fromclient
streamfromclient=new BufferedReader(new InputStreamReader((fromclient.getInputStream())));
//create a input stream for the socket
streamtoclient=new PrintStream(fromclient.getOutputStream());
//create an a output stream for the socket
String str=streamfromclient.readLine();
//read the message sent by client
System.out.println("Output Input From Vtcpd "+str);
streamtobackend.print(str);
streamtobackend = new PrintStream(clientsoc.getOutputStream());
//create an a output stream for the backend socket
streamfrombackend = new BufferedReader(new InputStreamReader(clientsoc.getInputStream()));
//create a input stream for the backend socket
str=streamfrombackend.readLine();
System.out.println("Output From Backend Client"+str);
streamtoclient.println(str);
}//end of while
catch(Exception e)
System.out.println("Exception "+e);
finally
try
fromclient.close();
catch(Exception e)
System.out.println("could not close connection "+e);
public static void main(String ar[])
new serl();
}

Srikandh,
Create a singelton pattern for you socket ( IP, port, etc..) and each time you read the input stream and write to the output stream, do the following to the socket to reset it in the working thread
fromclient.getInputStream().mark(0);
fromclient.getInputStream().reset();Hope this could help
Regards,
Alan Mehio
London,UK

Java Socket Connection Time out

Goal*
I want to check host/port availability of computers in our network (~100 computers) .. Just check if host is alive and if it has port 445 opened. I want to do this somehow in parallel, so the code execution is as quick as possible.
My implementation*
I do this by creating socket connection to the host. Something like this:
        Socket s = null;
        try {
            s = new Socket();
            InetSocketAddress socketAddress = new InetSocketAddress(ipAddress, 445);
            s.connect(socketAddress, 3000);
            if (s.isConnected()) {
                // do something
        } catch (ConnectException ex) {
            //exception thrown
        } catch (IOException ex1) {
            //exception thrown
        } finally {
            try {
                // close socket
                s.close();
            } catch (IOException ex) {
                Logger.getLogger(ComputerModel.class.getName()).log(Level.SEVERE, null, ex);
        }This code is executed in a loop, where a separate thread is created for every iteration = ~100 separate threads.
Problem:*
1.
It seems to me, that first ~10-15 connections are created ok, but then my code reaches 'IOException' catch block for every subsequent itteration and ex.getMessage() returns "connection time out" (I try to use different timeout values in the 2nd parameter. Values from 3000 up to 20000).
Is it valid to create 100 separate threads in a loop? Can't I make my NIC to bussy with this ??? What is the maximum ammount of threads, I can create? I did not use threads before, so I have no idea, if max values are near to 10, 100, 1000, or 10000 ..
2.
After my code is executed, I enter 'netstat -an' command in my command line and I get bunch of connections, which report status of SYN_SENT for several connections.
TCP 10.20.11.140:4557 10.30.11.119:445 SYN_SENT
TCP 10.20.11.140:4558 10.30.11.176:445 SYN_SENT
TCP 10.20.11.140:4559 10.30.11.100:445 SYN_SENT
TCP 10.20.11.140:4560 10.30.11.142:445 SYN_SENT
TCP 10.20.11.140:4561 10.30.11.171:445 SYN_SENT
TCP 10.20.11.140:4562 10.30.11.143:445 SYN_SENT
TCP 10.20.11.140:4563 10.30.12.12:445 SYN_SENT
TCP 10.20.11.140:4564 10.30.12.11:445 SYN_SENT
TCP 10.20.11.140:4565 10.30.12.21:445 SYN_SENT
TCP 10.20.11.140:4566 10.30.11.150:445 SYN_SENT
I also feel, that my computer network response (e.g. firefox browsing) is a bit slower ..
How shall I handle this problem properly?
Thx in advance,
Juraj

kajbj wrote:
tschodt wrote:
kajbj wrote:
The documentation for netstat explains what SYN_SENT is, but
I don't know why you have them.The app has asked the TCP stack to transmit SYN
the TCP stack is now waiting for SYN-ACK.
If there is no host at that IP address or a host that drops connections (SYN packets) for TCP port 445
there will never be a SYN-ACK.
After a few minutes the TCP stack will time out the connection attempt.Yes, I was rather commenting on why his hosts aren't answering. I thought that his case was that all of them should answer :)Akkurat. I was answering more for clarification.
Someone who does not know your posting history could easily assume you meant
it was a mystery why netstat was showing SYN_SENT.
And I figured it would not harm to hint that one possible reason would be that those machines are powered off (no host).

How to detact socket connection status

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