Reusing socket connection

I'm trying to write client & server application that needs to keep socket connection alive and be able to use the same socket to do multiple transactions. ( 1 transaction = Request & Response).
How can the server reliably inform the client about completion of data without closing the socket? The server doesn't know how much data is to be sent before the transaction begins.
Thank you!

EJP,
I'm trying to implement something like HTTP Keep-Alive, in my case it is always turned on.
Just like a HTTP client, when it sees "Connection: keep-alive" header, it won't terminate the connection even after it has received all data for that particular transaction. I'm looking for the same solution. But I don't know how I can implement it.
One solution that i can think is, have the server send 0 bytes say for 4 times & when client receives this sequence it will know the transaction has completed, but I'm not sure if this is the optimal solution.
My situation is very similar to the way HTTP client handles HTTP Keep-Alive connection with Chunked transfer
Thanks for your response :)

Similar Messages

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)

Urgent --- Persistent socket connection?

Hi, I have a question about the persistency of a Java Socket connection. Is it a valid idea to keep a java socket open for a long time? If so, what special care do I need to take?
My Java TCP/IP client runs as a NT service. It keeps getting input messages every few seconds, then send it thru a socket connection to a TCP/IP server. In order to avoid the overhead of opening and closing the socket every time the client gets a message to send, I want to keep the socket connection open and reuse it.
I was able to send hundreds of messages thru this way, then after a while, for no apparent reason,
the socket stops working, I typically get an exception like this:
java.net.SocketException: Connection Shutdown: JVM_recv in socket input stream read
at java.net.SocketInputStream.socketRead(Native Method)
at java.net.SocketInputStream.read (SocketInputStream.java:90)
at java.net.SocketInputStream.read (SocketInputStream.java:71)
at java.io.InputStreamReader.fill (InputStreamReader.java:163)
at java.io.InputStreamReader.read (InputStreamReader.java:239)
at java.io.BufferedReader.fill (BufferedReader.java:137)
at java.io.BufferedReader.readLine (BufferedReader.java, Compiled Code)
at java.io.BufferedReader.readLine (BufferedReader.java:329)
My programs runs on NT4.0, single-threaded. Any input would be greatly appreciated.

Is it a valid idea to keep a java socket open for a long time? If so, what
special care do I need to take?Depends.
First why keep it open? Your messages only arrive every couple of seconds, does opening/closing the connection take longer than that?
If you must then the complication you must deal with is that your code must deal with re-establishing the connection when it does fail. Opening/closing it every time avoids that issue. The connection will fail, because computers fail, networks fail and people make mistakes. Which doesn't mean that you shouldn't but merely that you should consider the implications of why you need to keep it open.

Persistent socket connection - socket write error

I'm connecting to a server using sockets. My application acts like a client, sending requests, and also like a server, listenning for notifications. I was using a client socket for the first task (send a message when required) and a server socket for the second (permanently listen for incoming messages). This needs to be some kind of persistent connection.
It happens now I'm required to send and receive using the same port. The only way I found to do this is to have a single socket (client) bound to a certain port. It connects to the server and one thread keeps listenning for incoming messages (by reading the input stream) while another process is launched whenever I need to send a message (by writing to the socket's output stream). The socket is created only once (when the application starts) and its output/input streams reused whenever needed.
This works well for a while. However, when I try to send a message after some idle time (lets say 20 minutes) strange things happen. The first attempt to send a message returns success (although nothing is actually received by the server). The second attempt returns java.net.SocketException: Software caused connection abort: socket write error. I don't understand this behaviour. Can there be a timeout? I only write to the socket after testing if it's connected.. So why is this failing? Also, any other ideas on how to send and receive using the same port? A different and better approach maybe..
Thanks in advance

Socket.isConnected just tells you whether you have personally called Socket.connect() or new Socket(host, port,...). It doesn't tell you anything about the state of the connection.
You should certainly issue periodic application 'pings' at suitable intervals, and many application protocols do this. For example, Java RMI reuses connections that are less than 15 seconds old but only if they pass a ping test.
In general however you can't insist on a persistent connection over TCP/IP, especially if you have this kind of hardware in the circuit. What you can do is recognize when the connection has been lost and form a new one. The network is going to fail somewhere some time and your program has to be robust against that.

Socket connect slow in JDK 1.5?

We recently began testing our Java Swing application with JDK 1.5, and we noticed that socket.connect()
calls are taking several seconds to return, when before in 1.4 the calls returned immediately.
Here is some sample code:
Socket sock = new Socket();
InetSocketAddress sockAddr = new InetSocketAddress(inAddress, portNum);
sock.connect(sockAddr, 2000);
What could be wrong? I've debugged the code and verified inAddress is an IP address,
not a hostname.
-Eric

Here is the list of enhancements in JDK1.5.
http://java.sun.com/j2se/1.5.0/docs/guide/net/enhancements-1.5.0.html
I wonder if any of them are having some effect in the slow connection.
There are some network properties that you can tweak with. Did you try them?
Here is the list
http://java.sun.com/j2se/1.5.0/docs/guide/net/properties.html

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

Problem with socket connection through Java Embedding...

We are trying to create a simple socket connection to a socket server through BPEL PM using the Java Embedding component.
BPEL Process : Client makes an asynchronous request. Passes an input variable. The input variable is sent to the Server Program through a socket connection through the Java embedding component.
Server: We are running a simple Socket Server program from command prompt.
The code below works fine as long as we do not try to receive a response from the server (Commented Code).
If we uncomment the code and try to receive a response, it refuses to create an instance for the BPEL Process. And sometimes restarts the BPEL Server.
Client Code:
String msg="NONE";
try{
org.w3c.dom.Element input = (org.w3c.dom.Element) getVariableData("inputVariable","payload","/client:clientProcessRequest/client:input");
msg = input.getNodeValue();
Socket clientsoc=new Socket("ServerIP",1000);
PrintWriter out1=new PrintWriter(clientsoc.getOutputStream());
out1.write(msg);
out1.flush();
BufferedReader cin1=new BufferedReader(new InputStreamReader(clientsoc.getInputStream()));
msg=cin1.readLine();
setVariableData("outputVariable","payload","/client:result",new String(msg));
clientsoc.close();
catch(UnknownHostException e)
System.err.println("Don't know about host: dev.");
System.exit(1);
catch (IOException e)
System.err.println("Couldn't get I/O for "+ "the connection to: dev.");
System.exit(1);
}

Repost

Problem with socket connection in midp 2.0

hello everyone.
I'm new one in j2me and I am learning socket connection in j2me. I'm using basic socket,datagram example wich is come with sun java wireless toolkit 2.5. for it i wrote small socket server program on c# and tested it example on my pc and its working fine. also socket server from another computer via internet working fine. But when i instal this socket example into my phone on nokia n78 (Also on nokia 5800) it's not working didn't connect to socket server.. On phone I'm using wi-fi internet. Can anybody help me with this problem? I hear it's need to modify manifest file and set appreciate pressions like this
MIDlet-Permissions: javax.microedition.io.Connector.socket,javax.microedition.io.Connector.file.write,javax.microedition.io.Connector.ssl,javax.microedition.io.Connector.file.read,javax.microedition.io.Connector.http,javax.microedition.io.Connector.https
is it true?
can anybody suggest me how can i solve this problem?
where can I read full information about socket connection specifiecs in j2me?
Thanks.

Maybe this can be helpful:
[http://download-llnw.oracle.com/javame/config/cldc/ref-impl/midp2.0/jsr118/index.html]
you can check there the Datagram interface anda DatagramConnection interface and learn a little about that.
If the client example runs fine in the wireless toolkit emulator, it should run the same way in your phone; i suggest to try to catch some exception that maybe is hapenning and display it on a Alert screen, this in the phone.

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 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();
}

Connect Flash to Serial Port with Local Socket Connection

Hey all,
So, I am trying to connect a Flash movie to a serial port
and have it react to the input coming in. Of course, Flash does not
have this capability built in, so I need a workaround. I also
program in Director, and there are easier ways to deal with this
there, but since there hasn't been an update in years, and for
other technical reasons, I would like to use a pure Flash program.
I also need to take advantage of some of the new hardware
acceleration improvements and horizontal sync issues that come with
running the Flash player full screen. So, there are some tools out
there that will let me stream the input from the serial port to a
web address. I figure I could use the local address and assign a
port number, then use Flash to create a local socket connection. I
am having issues opening ports on my computer, and a few other
things, but in theory, I think it should work. I know that I won't
get all the answers here, but if anyone has done anything of the
sort, or might know of some similar projects, it would really help.
I am more of a Director/Flash programmer, and not so much one on
the system level. So, opening local sockets, etc, while I am sure I
can figure it out, is still a bit beyond me. Thanks all!
- Bruce

You may want to look into flash remoting, which would allow
you to push content to the flash movie. You could then write a
proxy between the source of your stream and flash the remoting
server.

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?

Reusing socket connection

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