Socket connections on LAN?
I am designing a java application which will have 100 clients and a database server over LAN. There is no application server, only core java is used to write the programming logic. Now, to read, update or write anything to the database a bare socket connection will be made by the client to the server over LAN. Please tell me is it safe to perform this kind of communication? Will the network connection sustain for a long time or there are many chances that it may break easily? In no case will I be able to use an application server. Can I design such an application that communicates through bare sockets with no protection as such?
If you use stream sockets your connection will survive for long periods of time. I have an application that connects to a mainframe by sockets and to Oracle using OCI (which uses sockets) that stays up for a week at a time, only stopping when the mainframe goes down for weekly maintenance. It recovers when the mainframe restarts by attempting to reconnect once a minute.
This said, you still should deal with the inevitable situation where the connection is lost due to network problems or aproblemon your server.
Similar Messages
-
Periodic socket connection errors
I am experiencing a periodic error when accessing a Servlet running under
weblogic 6 sp2 on Windows 2000. Usually the second time my servlet is
accessed I see the connection error and then periodically after that. Here
is the stack trace:
.lang.NullPointerException
at weblogic.socket.TunnelContext.getServlet(TunnelContext.java:24)
at
weblogic.servlet.internal.MuxableSocketHTTP.dispatch(MuxableSocketHTTP.java:
465)
at weblogic.socket.NTSocketMuxer.processSockets(NTSocketMuxer.java:638)
at weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:23)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:137)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
>
<Oct 1, 2001 9:38:01 PM EDT> <Error> <HTTP> <Connection failure
java.lang.NullPointerException
at weblogic.socket.TunnelContext.getServlet(TunnelContext.java:24)
at
weblogic.servlet.internal.MuxableSocketHTTP.dispatch(MuxableSocketHTTP.java:
465)
at weblogic.socket.NTSocketMuxer.processSockets(NTSocketMuxer.java:638)
at weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:23)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:137)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
I traced this in the debugger and found that the first error occurs before
my servlet is even invoked. The second error occurs after I try to read
from the ServletInputStream object. When the error occurs I must kill the
client request, which hangs, and then subsequent requests are fine.
I have not seen anything like this in these newsgroups. Does anyone have
any ideas as to why this is happening?
Thanks,
Mark
Hi, I'm facing same problem. Did you guys get a solution for this?
Thanks,
Tarkeshwar
"Mark Priest" <[email protected]> wrote:
>It sounds like we are both experiencing a similar problem on different
>platforms. Will someone from Bea please comment on this?
>
>Thanks,
>Mark
>
>"Alexis Berger" <[email protected]> wrote in message
>news:[email protected]...
>> Mark,
>>
>> I currently got the same problem.
>> my config is Weblogic 6.0 (no SP) under Linux.
>>
>> In fact, I got a Tomcat server (with an application - a servlet -)
>on my
>> LAN, which calls my application under my Weblogic server (a servlet
>calling
>> some EJBs...)
>> No problem at the first connection, then the second fails with this
>> exception :
>>
>> I don't know what happens between tomcat and weblogic but what I traced
>is
>> that :
>> 1) Tomcat creates a socket connection with Weblo
>> 2) Weblo listens to Tomcat for an InputStream
>> 3) Tomcat sends data via an OutputStream
>> 4) Weblo receives nothing !!!! <---- problem ? :)
>>
>> Here is my exception...
>>
>>
>> <Error> <Posix Performance Pack> <Uncaught
>> Throwable in processSockets
>> java.lang.NullPointerException
>> at weblogic.socket.TunnelContext.getServlet(TunnelContext.java:24)
>> at
>>
>weblogic.servlet.internal.MuxableSocketHTTP.dispatch(MuxableSocketHTTP.java:
>> 459)
>> at
>>
>weblogic.socket.PosixSocketMuxer.deliverGoodNews(PosixSocketMuxer.java:449)
>> at
>> weblogic.socket.PosixSocketMuxer.processSockets(PosixSocketMuxer.java:378)
>> at
>weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:23)
>> at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:137)
>> at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
>> >
>>
>>
>>
>> "Mark Priest" <[email protected]> a écrit dans le message de
>news:
>> [email protected]...
>> > I am experiencing a periodic error when accessing a Servlet running
>under
>> > weblogic 6 sp2 on Windows 2000. Usually the second time my servlet
>is
>> > accessed I see the connection error and then periodically after that.
>> Here
>> > is the stack trace:
>> >
>> > .lang.NullPointerException
>> > at weblogic.socket.TunnelContext.getServlet(TunnelContext.java:24)
>> > at
>> >
>>
>weblogic.servlet.internal.MuxableSocketHTTP.dispatch(MuxableSocketHTTP.java:
>> > 465)
>> > at weblogic.socket.NTSocketMuxer.processSockets(NTSocketMuxer.java:638)
>> > at
>> weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:23)
>> > at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:137)
>> > at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
>> > >
>> > <Oct 1, 2001 9:38:01 PM EDT> <Error> <HTTP> <Connection failure
>> > java.lang.NullPointerException
>> > at weblogic.socket.TunnelContext.getServlet(TunnelContext.java:24)
>> > at
>> >
>>
>weblogic.servlet.internal.MuxableSocketHTTP.dispatch(MuxableSocketHTTP.java:
>> > 465)
>> > at weblogic.socket.NTSocketMuxer.processSockets(NTSocketMuxer.java:638)
>> > at
>> weblogic.socket.SocketReaderRequest.execute(SocketReaderRequest.java:23)
>> > at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:137)
>> > at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)
>> >
>> > I traced this in the debugger and found that the first error occurs
>before
>> > my servlet is even invoked. The second error occurs after I try
>to read
>> > from the ServletInputStream object. When the error occurs I must
>kill
>the
>> > client request, which hangs, and then subsequent requests are fine.
>> >
>> > I have not seen anything like this in these newsgroups. Does anyone
>have
>> > any ideas as to why this is happening?
>> >
>> > Thanks,
>> > Mark
>> >
>> >
>> >
>> >
>> >
>>
>>
>
>
-
Failed to open a socket connection to the Authentication Manager
Hello,
When I use utcapture command, I get the error *�Failed to open a socket connection to the Authentication Manager�*.
SO: Solaris 10 8/07
SRSS: Sun Ray Server Software 4.0
LAN Configuration
Thanks.Since the question was also posted to the sunray-users alias, see http://www.filibeto.org/pipermail/sunray-users/2007-December/008281.html for the answer. (Which currently seems to be that the Sun Ray auth daemon was not running.)
-
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.
-EricHere 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 ???
namancIf 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,,,,,,,,,,,,,,,,*32Actually 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 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,
thanksAll 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();
} -
Competition problem between Windows 8.1 and Windows 7 on Photosmart C5180 connected via LAN
Hello everyone, I am writing because I need some advice / help on a problem last night while configuring a small network.
The network is made up as follows:
2 notebook: Windows 8.1 and Windows 7
3 different printers:
2 USB connected to the respective notebook,
1 HP Photosmart C5180 network printer connected via LAN via a router.
The situation is the following:
both notebooks recognize the various printers and are able to send and print documents but,
when the print command starts from both notebook SIMULTANEOUSLY or at a distance of a few seconds, the only document printed is ALWAYS the one sent from the notebook with WINDOWS 8.1. The other one submitted by WINDOWS 7 IS LOST without being reported.
So if I ask of you is someone experienced in the print queues, print drivers, competition in the print jobs that can help me in solving this problem.
Thanks in advanceHello cesco,
Welcome to the HP Forums.
I see that you are having a communication issue when attempting to print on two separate printers at the same time.
This will be a communication issue for sure. The computer can only send to one printer at a time. You will have to print to one printer, wait for it to finnish the print job and then send it to the other printer.
There is no way that you can print from one computer to two separate printers at the same time.
Thanks for your time.
Cheers,
Click the “Kudos Thumbs Up" at the bottom of this post to say “Thanks” for helping!
Please click “Accept as Solution ” if you feel my post solved your issue, it will help others find the solution.
W a t e r b o y 71
I work on behalf of HP -
Disable Internet Connection on LAN computers on Linksys E2500
Hi,
I am new here, and going to setting up my router in my small office.
I have a Linksys E2500, and going to disable internet connection on computers that connected via LAN cable.
So, this is how I am going to set my office.
Internet
|
modem
|
Linksys E2500
(192.168.1.1)
| |
Hub A Hub B
PC 1 PC 2 PC 3 PC 4
Hub A and Hub B are in different floor.
Do these Hub A and Hub B still give the same range of IP Address from linksys (192.168.1.x) to the PCs below them, like PC 1 got 192.168.1.2, PC 2 got 192.168.1.3 and go on? Can I reserve an static IP Address to each PCs, and disable internet only on PCs below Hub B (PC 3 and PC 4)? I cannot find any controls for disabling internet connection on LAN interface from the E2500 Setup Interface. There are only Wireless MAC Filtering and no LAN MAC Filtering.
If this thing sounds stupid, I am sorry but I have no experience in setting network here. I hope someone can help me out.
Thanks a lot.I agree with FurryNutz. You will need an IP-enabled device for the router block it via Parental Controls. If you have wireless bridge or a manageable switch, you can block that and all the devices connected to it should also be blocked from internet access.
I think you can set Static DNS on the computers under Hub B to 0.0.0.0 which will not allow them to access the internet but are still within the router's local network.
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