Server Socket Binding
We use a ServerSocket Listening on port 162 to receive Traps from a Remote agent. If the application is launched on a multi-homed system (system with Multiple IP Addresses), which IP Address does the socket bind to ?
Is it the case that the Socket binds to a port and not to a IP and hence IP to which it is bound does not matter at all?
Kindly respond
We use a ServerSocket Listening on port 162 to receive
Traps from a Remote agent. If the application is
launched on a multi-homed system (system with Multiple
IP Addresses), which IP Address does the socket bind
to ?It depends of the ServerSocket constructor you use. If you only say:
ServerSocket ss = new ServerSocket( port );it will bind every IP address your machine has. However, if you use:
ServerSocket ss = new ServerSocket(port, backlog, bindAddr) ;Your server socket will be bound to the InetAddress object bindAddr (the IP you need to be bounded to).
HTH
Similar Messages
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Socket Bind Error: OSX 10.6.8 Server
So I have a server that is just a file share. Never had an issue before. We recently moved it to another location and changed its IP address. Now the logs are filled up with these.
Apr 17 11:41:48 bigmac com.apple.gw_logd[68]: socket bind: Can't assign requested address
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Can i run UDP client and UDP server socket program in the same pc ?
hi all.
when i execute my UDP client socket program and UDP server socket program in the same pc ,
It's will shown the error msg :
"Address already in use: Cannot bind"
but if i run UDP client socket program in the remote pc and UDP server socket program run in local pc , it's will success.
anybody know what's going on ?
any help will be appreciated !bobby92 wrote:
i have use a specified port for UDP server side , and for client define the server port "DatagramSocket clientSocket= new DatagramSocket(Server_PORT);"Why? The port you provide here is not the target port. It's the local port you listen on. That's only necessary when you want other hosts to connect to you (i.e. when you're acting as a server).
The server should be using that constructor, the client should not be specifying a port.
so when i start the udp server code to listen in local pc , then when i start UDP client code in local pc ,i will get the error "Address already in use: Cannot bind"Because your client tries to bind to the same port that the server already bound to. -
Problem socket.bind() with multiple modems and multiple IPs
I've connected 2 or more modems in Windows control panel and made up windows dail ups. Then I dail up each modem and obtain the local DHCP IPs of each modem.
My target is : to set up sockets using separate modems.
the code is like: create a socket instance , and use Socket.bind()method to bind the socket to a specified modem's local IP , then do socket.connect().
but the problem is : although there are several modem dail ups and at the same time I bind each socket to different IPs , the program always connect via the first modem dailed up.
Does Socket.bind() method really bind the socket connection to the IP's or hardwares?I think you are trying to use a Socket where you want a ServerSocket to accept the incoming connection. Check this out (I have underlined what
should interest you):
public ServerSocket(int port, int queueLength) throws IOException, BindException
This constructor creates a ServerSocket on the specified port with a queue length of your choosing. If the machine has multiple network interfaces or IP addresses, then it listens on this port on all those interfaces and IP addresses. The queueLength argument sets the length of the queue for incoming connection requests--that is, how many incoming connections can be stored at one time before the host starts refusing connections. Some operating systems have a maximum queue length, typically five. If you try to expand the queue past that maximum number, the maximum queue length is used instead. If you pass 0 for the port number, the system selects an available port.
For example, to create a server socket on port 5,776 that would hold up to 100 incoming connection requests in the queue, you would write:
try {
ServerSocket httpd = new ServerSocket(5776, 100);
catch (IOException e) {
System.err.println(e);
}The constructor throws an IOException (specifically, a BindException) if the socket cannot be created and bound to the requested port. An IOException when creating a ServerSocket almost always means one of two things. Either the specified port is already in use, or you do not have root privileges on Unix and you're trying to connect to a port from 1 to 1,023.
So once you receive a connection, it looks like it is up to you parse any
relevant info you want out of the Socket you get from ServerSocket.accept();
-Cludge -
I'm getting a new exception:
SEVERE: Problem establishing server socket
java.net.BindException: Address already in use: JVM_Bind
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:359)
at java.net.ServerSocket.bind(ServerSocket.java:319)
at java.net.ServerSocket.<init>(ServerSocket.java:185)
at com.cboe.support.servlet.servletutilities.Daemon.run(DaemonHttpServlet.java:63)
For some reason, it's failing when i'm trying to create the serverSocket(listens for new connections). Note: I am using Tomcat 5.5.7. This socket is being created within a servlet. Any thoughts?determen, u said that this socket is being created within a servlet. Are u making sure to close this socket whenver the servlet has been called and performed it's job. Try restarting tomcat, then try calling the servlet containing that code, if it functions well in the first call, then generates exceptions on the second, this means that the socket is not being closed whenever the servlet has finished its job, and the port is still being in use.
-
i create a server socket....and in finally clause i close the socket.
now most of the time this works fine.
however while im still testing my program is crashes sometimes.
then removing bind exception is annoying.
isnt there anyway (like as it is in jacORB) to check for and remove stale reference on a port???
Message was edited by:
luqmanhttp://java.sun.com/j2se/1.5.0/docs/api/java/net/Serve
rSocket.html#setReuseAddress(boolean)
Set this to 'true'.
Development only, don't let this leak into production.thanks works perfect now. -
Reading text from server socket stream
I have a basic cd input program i've been trying to figure out the following problem for a while now, the user enters the artist and title etc and then a DOM (XML) file is created in memory this is then sent to the server. The server then echos back the results which is later printed on a html page by reading the replys from the server line by line.
The server must be run it listens for clients connecting the clients connect and send DOM documents through the following jsp code.
<%@page import="java.io.*"%>
<%@page import="java.net.*"%>
<%@page import="javax.xml.parsers.*"%>
<%@page import="org.w3c.dom.*"%>
<%@page import="org.apache.xml.serialize.*"%>
<%!
public static final String serverHost = "cdserver";
public static final int serverPort = 10151;
%>
<hr />
<pre>
<%
Socket mySocket = null; // socket object
PrintWriter sockOut = null; // to send data to the socket
BufferedReader sockIn = null; // to receive data from the socket
try {
// #1 add line that creates a client socket
mySocket = new Socket(serverHost, serverPort);
// #2 add lines that create input and output streams
// attached to the socket you just created
sockOut = new PrintWriter(mySocket.getOutputStream(), true);
sockIn = new BufferedReader(new InputStreamReader(mySocket.getInputStream()));
} catch (UnknownHostException e) {
throw e; // This time the JSP can handle the exception, not us
} catch (IOException e) {
throw e; // This time the JSP can handle the exception, not us
String cdTitle, cdArtist, track1Title, track1Time, track1Rating;
// Retrieve the HTML form field values
cdTitle = request.getParameter("cdtitle");
cdArtist = request.getParameter("cdartist");
track1Title = request.getParameter("track1title");
track1Time = request.getParameter("track1time");
track1Rating = request.getParameter("track1rating");
// Create a new DOM factory, and from that a new DOM builder object
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
// Note that we are creating a new (empty) document
Document document = builder.newDocument();
// The root element of our document wil be <cd>
// It gets stored as the child node of the whole document (it is the root)
Element rootElement = document.createElement("cd");
document.appendChild(rootElement);
// Create an element for the CD title called <title>
Element cdTitleElement = document.createElement("title");
// Add a text code under the <title> element with the value that
// the user entered into the title field of the web form (cdTitle)
cdTitleElement.appendChild(document.createTextNode(cdTitle));
// Place the <title> element underneath the <cd> element in the tree
rootElement.appendChild(cdTitleElement);
// Create an <artist> element with the form data, place underneath <cd>
Element cdArtistElement = document.createElement("artist");
cdArtistElement.appendChild(document.createTextNode(cdArtist));
rootElement.appendChild(cdArtistElement);
// Create a <tracklist> element and place it underneath <cd> in the tree
// Note that it has no text node associated with it (it not a leaf node)
Element trackListElement = document.createElement("tracklist");
rootElement.appendChild(trackListElement);
// In this example we only have one track, so it is not necessary to
// use a loop (in fact it is quite silly)
// But the code below is included to demonstrate how you could loop
// through and add a set of different tracks one by one if you
// needed to (although you would need to have the track data already
// stored in an array or a java.util.Vector or similar
int numTracks = 1;
for (int i=0; i<numTracks; i++) {
String trackNum = Integer.toString(i+1);
Element trackElement = document.createElement("track");
trackElement.setAttribute("id", trackNum);
trackListElement.appendChild(trackElement);
// Track title element called <title>, placed underneath <track>
Element trackTitleElement = document.createElement("title");
trackTitleElement.appendChild(document.createTextNode(track1Title));
trackElement.appendChild(trackTitleElement);
// Track time element called <time>, placed underneath <track>
Element trackTimeElement = document.createElement("time");
trackTimeElement.appendChild(document.createTextNode(track1Time));
trackElement.appendChild(trackTimeElement);
// Track rating element called <rating>, placed underneath <track>
Element trackRatingElement = document.createElement("rating");
trackRatingElement.appendChild(document.createTextNode(track1Rating));
trackElement.appendChild(trackRatingElement);
OutputFormat format = new OutputFormat();
format.setIndenting(true);
// Create a new XMLSerializer that will be used to write out the XML
// This time we will serialize it to the socket
// #3 change this line so that it serializes to the socket,
// not to the "out" object
XMLSerializer serializer = new XMLSerializer(writer, format);
serializer.serialize(document);
// Print out a message to indicate the end of the data, and
// flush the stream so all the data gets sent now
sockOut.println("<!--QUIT-->");
sockOut.flush();
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromServer;
String fromUser;
#4 add a while loop that reads text from the
server socket input stream, line by line, and prints
it out to the web page, using out.println(...);
Note that because the reply from the server will contain
XML, you will need to call upon the toHTMLString() method
defined below to escape the < and > symbols so that they
will display correctly in the web browser.
Also note that as you receive the reply back from the
server, you should look out for the special <!--QUIT-->
string that will indicate when there is no more data
to receive.
while ((fromServer = sockIn.readLine()) != null) {
out.println(sockIn.readLine());
// If the reply from the server said "QUIT", exit from the
// while loop by using a break statement.
if (fromServer.equals("QUIT")) {
out.println("Connection closed - good bye ...");
// Print the text from the server out to the user's screen
out.println("Reply from Server: " + fromServer);
// Now read a line of text from the keyboard (typed by user)
fromUser = stdIn.readLine();
// If it wasn't null, print it out to the screen, and also
// print a copy of it out to the socket
if (fromUser != null) {
out.println("Client: " + fromUser);
sockOut.println(fromUser);
// Close all the streams we have open, and then close the socket
sockOut.close();
sockIn.close();
mySocket.close();
%>
I'm suppose to modify the commented sections labled with #.
#1,2 are correct but i have doubts on the 3rd and 4th modification.
for #3 i changed so i serializes to the socket not to the "out" object:
from
XMLSerializer serializer = new XMLSerializer(out, format);
to
XMLSerializer serializer = new XMLSerializer(writer, format);
with "out" it prints out some of the results entered but it just hangs i'm thinking it might be the while loop that i added in #4. If i changed it to serialize the socket XMLSerializer serializer = new XMLSerializer(writer, format); it doesn't print out nothing at all; just a blank screen where it hangs.
I can post the rest of the code (server thats in java and cdinput.html) but since i want to keep my post short and if required i'll post it later on i also omitted some of the code where it creates the DOM textnodes etc to keep my post short.On your previous thread, why did you say the server was using http POST and application/xml content type when it quite obviously isn't, but a direct socket communication that abuses XML comments for message end delimiters?
The comments imply you need to wait for "<!--QUIT-->" on a line by itself, but your loop is waiting for "QUIT".
Pete -
Can't open HTTP server socket on port 50000 in dispatcher
We get the following message in the console_log for the dispatcher.
ID000544: Error starting service http. Can't start the service due to java.io.IO
Exception: Can't open HTTP server socket on port 50000
[ServiceManager]: ID000544: Error starting service http. Can't start the service
due to java.io.IOException: Can't open HTTP server socket on port 50000
[Framework -> criticalShutdown] Service http startup error!
Anyone have any ideas what might be the problem?
Thanks,
KeithHello Keith,
this errors occurs when the port http 50000 is already taken. Please could you check if this port on your machine is free or an other dispacther instance is already started on same machine. You can change the port in sap j2ee config tool (dispatcher-> services->http)
Best Regards,
Fabrice -
Can't connect to my server socket using external IP
Hi I'm very new to Java programming, and I'm learning all the core things I need to understand so that I can make a simple networked game using a command-line server and applet clients. I tried the networking tutorial and it worked perfectly on my machine.
However, it only works if I supply the client with my INTERNAL IP. When I give it my EXTERNAL IP it cannot connect to the server socket. The error thrown is a IOException.
The code:
import java.io.*;
import java.net.*;
public class KnockKnockClient {
public static void main(String[] args) throws IOException {
Socket kkSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try {
kkSocket = new Socket("192.168.2.3", 4444);
out = new PrintWriter(kkSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream()));
} catch (UnknownHostException e) {
System.err.println("Don't know about host.");
System.exit(1);
} catch (IOException e) {
System.err.println("Couldn't get I/O for the connection.");
System.exit(1);
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromServer;
String fromUser;
while ((fromServer = in.readLine()) != null) {
System.out.println("Server: " + fromServer);
if (fromServer.equals("Bye."))
break;
fromUser = stdIn.readLine();
if (fromUser != null) {
System.out.println("Client: " + fromUser);
out.println(fromUser);
out.close();
in.close();
stdIn.close();
kkSocket.close();
}The code works fine with my internal IP (192.168.2.3) but not my external IP (86.3.51.171). Any ideas about how to fix it?Not quite sure I understand. Do you use the external IP with clients
from the external network or with clients from the internal network?
But regardless, I assume your Java code is correct since it works
on the internal network. Try this command:
telnet 192.168.2.3 4444
from the internal network. I expect it to show "Server: ...", whatever the
server sends. If this works, it means we can indeed use telnet to
test connectivity. Now do:
telnet 86.3.51.171 4444
from the machine that gives you problems. If this does not work
(connection lost or something like this), it means your Java code is OK
and you need to do some configuration at your router.
If this works, which I doubt, I am on the wrong track. -
FU Ant task failure: java.util.concurrent.ExecutionException: could not close client/server socket
We sometimes see this failure intermitently when using the FlexUnit Ant task to run tests in a CI environment. The Ant task throws this exception:
java.util.concurrent.ExecutionException: could not close client/server socket
I have seen this for a while now, and still see it with the latest 4.1 RC versions.
Here is the console output seen along with the above exception:
FlexUnit player target: flash
Validating task attributes ...
Generating default values ...
Using default working dir [C:\DJTE\commons.formatter_swc\d3flxcmn32\extracted\Source\Flex]
Using the following settings for the test run:
FLEX_HOME: [C:\dev\vert-d3flxcmn32\302100.41.0.20110323122739_d3flxcmn32]
haltonfailure: [false]
headless: [false]
display: [99]
localTrusted: [true]
player: [flash]
port: [1024]
swf: [C:\DJTE\commons.formatter_swc\d3flxcmn32\extracted\build\commons.formatter.tests.unit.sw f]
timeout: [1800000ms]
toDir: [C:\DJTE\commons.formatter_swc\d3flxcmn32\reports\xml]
Setting up server process ...
Entry [C:\DJTE\commons.formatter_swc\d3flxcmn32\extracted\build] already available in local trust file at [C:\Users\user\AppData\Roaming\Macromedia\Flash Player\#Security\FlashPlayerTrust\flexUnit.cfg].
Executing 'rundll32' with arguments:
'url.dll,FileProtocolHandler'
'C:\DJTE\commons.formatter_swc\d3flxcmn32\extracted\build\commons.formatter.tests.unit.swf '
The ' characters around the executable and arguments are
not part of the command.
Starting server ...
Opening server socket on port [1024].
Waiting for client connection ...
Client connected.
Setting inbound buffer size to [262144] bytes.
Receiving data ...
Sending acknowledgement to player to start sending test data ...
Stopping server ...
End of test data reached, sending acknowledgement to player ...
When the problem occurs, it is not always during the running of any particular test (that I am aware of). Recent runs where this failure was seen had the following number of tests executed (note: the total number that should be run is 45677): 18021, 18, 229.
Here is a "good" run when the problem does not occur:
Setting inbound buffer size to [262144] bytes.
Receiving data ...
Sending acknowledgement to player to start sending test data ...
Stopping server ...
End of test data reached, sending acknowledgement to player ...
Closing client connection ...
Closing server on port [1024] ...
Analyzing reports ...
Suite: com.formatters.help.TestGeographicSiteUrls
Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.008 sec
Suite: com.formatters.functionalUnitTest.testCases.TestNumericUDF
Tests run: 13, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.071 sec
Results :
Tests run: 45,677, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 201.186 sec
Has anyone else ran across this problem?
Thanks,
TrevorI am not sure if this information will help everyone, but here goes...
For us, these problems with FlexUnit tests crashing the Flash Player appear to be related to couple of factors. Recently, we moved up from Flex 3.2 to Flex 4.1 as our development baseline. Many people complained that their development environment (Flash Builder, etc.) was much more unstable. Apparently, 4.1 produces SWFs that require more memory to run than 3.2 does? Anyway, we still had Flash Player 10.1 as our runtime baseline. Apparently, that version of the player was not as capable of running larger FlexUnit test SWFs, and would crash (as I posted months earlier). I upgraded to the latest 10.3 standalone player versions, and the crashes have now ceased. It would be nice to know exactly what was causing the crashes, but memory management (or lack of) is my best guess.
So, if you are seeing these issues, try upgrading to the latest Flash Player version.
Regards,
Trevor -
How to detect client socket shutdowns in server socket
Hi,
Hoping to get some help with this. I am writing this program that implements a socket server that accepts a single client socket (from a third-party system). This server receives messages from another program and writes them to the client socket. It does not read anything back from the client. However, the client (which I have no control over) disconnects and reconnects to my server at random intervals. My issue is I cannot detect when the client has disconnected (normally or due to a network failure), hence am unable to accept a fresh connection from the client. Here's my code for the server.
ServerSocket serverSocket = null;
Socket clientSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try{
if (serverSocket == null){
serverSocket = new ServerSocket(4511);
clientSocket = serverSocket.accept();
System.out.println("Accepted client request ... ");
out = new PrintWriter(clientSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
System.out.println("Input / Output streams intialized ...");
while (true){
System.out.println("Is Client Socket Closed : " + clientSocket.isClosed());
System.out.println("Is Client Socket Connected : " + clientSocket.isConnected());
System.out.println("Is Client Socket Bound : " + clientSocket.isBound());
System.out.println("Is Client Socket Input Shutdown : " + clientSocket.isInputShutdown());
System.out.println("Is Client Socket Output Shutdown : " + clientSocket.isOutputShutdown());
System.out.println("Is Server Socket Bound : " + serverSocket.isBound());
System.out.println("Is Server Socket Closed : " + serverSocket.isClosed());
messageQueue = new MessageQueue(messageQueueDir+"/"+messageQueueFile);
//get Message from Queue Head (also removes it)
message = getQueueMessage(messageQueue);
//format and send to Third Party System
if (message != null){
out.println(formatMessage(message));
System.out.println("Sent to Client... ");
//sleep
System.out.println("Going to sleep 5 sec");
Thread.sleep(5000);
System.out.println("Wake up ...");
}catch(IOException ioe){
System.out.println("initSocketServer::IOException : " + ioe.getMessage());
}catch(Exception e){
System.out.println("initSocketServer::Exception : " + e.getMessage());
}I never use the client's inputstream to read, although I have declared it here. After the client is connected (it enters the while loop), it prints the following. These values stay the same even after the client disconnects.
Is Client Socket Closed : false
Is Client Socket Connected : true
Is Client Socket Bound : true
Is Client Socket Input Shutdown : false
Is Client Socket Output Shutdown : false
Is Server Socket Bound : true
Is Server Socket Closed : false
So, basically I am looking for a condition that detects that the client is no longer connected, so that I can bring serverSocket.accept() and in and out initializations within the while loop.
Appreciate much, thanks.Crossposted and answered.
-
Problems Reading SSL server socket data stream using readByte()
Hi I'm trying to read an SSL server socket stream using readByte(). I need to use readByte() because my program acts an LDAP proxy (receives LDAP messages from an LDAP client then passes them onto an actual LDAP server. It works fine with normal LDAP data streams but once an SSL data stream is introduced, readByte just hangs! Here is my code.....
help!!! anyone?... anyone?
1. SSL Socket is first read into " InputStream input"
public void run()
Authorization auth = new Authorization();
try {
InputStream input = client.getInputStream();
while (true)
{ StandLdapCommand command;
try
command = new StandLdapCommand(input);
Authorization t = command.get_auth();
if (t != null )
auth = t;
catch( SocketException e )
{ // If socket error, drop the connection
Message.Info( "Client connection closed: " + e );
close( e );
break;
catch( EOFException e )
{ // If socket error, drop the connection
Message.Info( "Client connection close: " + e );
close( e );
break;
catch( Exception e )
//Way too many of these to trace them!
Message.Error( "Command not processed due to exception");
close( e );
break;
//continue;
processor.processBefore(auth, command);
try
Thread.sleep(40); //yield to other threads
catch(InterruptedException ie) {}
catch (Exception e)
close(e);
2 Then data is sent to an intermediate function
from this statement in the function above: command = new StandLdapCommand(input);
public StandLdapCommand(InputStream in) throws IOException
message = LDAPMessage.receive(in);
analyze();
Then finally, the read function where it hangs at "int tag = (int)din.readByte(); "
public static LDAPMessage receive(InputStream is) throws IOException
* LDAP Message Format =
* 1. LBER_SEQUENCE -- 1 byte
* 2. Length -- variable length = 3 + 4 + 5 ....
* 3. ID -- variable length
* 4. LDAP_REQ_msg -- 1 byte
* 5. Message specific structure -- variable length
DataInputStream din = new DataInputStream(is);
int tag = public static LDAPMessage receive(InputStream is) throws IOException
* LDAP Message Format =
* 1. LBER_SEQUENCE -- 1 byte
* 2. Length -- variable length = 3 + 4 + 5 ....
* 3. ID -- variable length
* 4. LDAP_REQ_msg -- 1 byte
* 5. Message specific structure -- variable length
DataInputStream din = new DataInputStream(is);
int tag = (int)din.readByte(); // sequence tag// sequence tag
...I suspect you are actually getting an Exception and not tracing the cause properly and then doing a sleep and then getting another Exception. Never ever catch an exception without tracing what it actually is somewhere.
Also I don't know what the sleep is supposed to be for. You will block in readByte() until something comes in, and that should be enough yielding for anybody. The sleep is just literally a waste of time. -
Server Socket does not read data input stream
Hi all,
I am very newbie to Java Network programming with sockets and multi-threading.
But I am obliged to develop a chat system written in Applets which can be placed on the website and used by visitors who come to my website.
In order to understand this, I have tested a basic web chat program I downloaded from the Internet which use sockets and multi-threadings. The program work fine, no bugs at all at both compilation and run time. I noticed that all three streams for Client side (i.e. first one is input stream used receiving data from User; the second one is socket input stream used for receiving data from Server socket, and the third is socket output stream used for writing data to server socket) were established. And the same, two socket streams (input & output) for Server side were also connected when running program giving right port number and IP address of the server.
The problem is both server and client sockets do not read data using the following stream classes:
1. DataStreamInput: I use input.readUTF() method
2. or BufferedReader: I use input.readLine() method
The example of the codes are below:
private BufferedReader input = null;
private PrintWriter output = null;
private Socket socket = null;
public void open() throws IOException
{ input = new BufferedReader(new
InputStreamReader(socket.getInputStream()));
System.out.println("Server socket input stream was created, and");
output = new PrintWriter(socket.getOutputStream());
System.out.println("Server socket output stream was created");
public void run()
{ System.out.println("Server Thread " + clientPort + " running.");
while (true)
{ try
System.out.println("Server is reading data from Client, wait...");
String fromClient = input.readLine();
System.out.println("Server received a message on " + clientPort + ".");
catch(IOException ioe)
{ System.out.println(clientPort + " ERROR reading: " + ioe.getMessage());
server.remove(clientPort);
stop();
The problem is at the line: String fromClient = input.readLine(); in the run() method? What is wrong with the codes above?
Note: I also try to use original codes which use readUTF() method in DataStreamInput class instead using readLine() in BufferedReader. Both methods dont read data from inputstream socket?
I very appreciate any help/advice from experienced developers.
Best regardsHi,
Yes. The readLine() method hangs! After the test, the execuation of the program is stopped at the line of readLine() method; it does not pass it?
There is no problem with writing to Server socket. After the test, the program pass through flush() method. Here is the code for writing to sever socket within ChatClient (client side socket) class:
private BufferedReader input = null;
private PrintWriter output = null;
public ChatClient(String serverName, int serverPort)
{ System.out.println("Establishing connection. Please wait ...");
try
{ socket = new Socket(serverName, serverPort);
System.out.println("Connected: " + socket);
start();
catch(UnknownHostException uhe)
{ System.out.println("Host unknown: " + uhe.getMessage()); }
catch(IOException ioe)
{ System.out.println("Unexpected exception: " + ioe.getMessage()); }
public void start() throws IOException
{ input = new BufferedReader (new
InputStreamReader(System.in));
System.out.println("Client User input stream was created,");
output = new PrintWriter(socket.getOutputStream());
System.out.println("Client Socket output stream was established, and");
if (thread == null)
{ client = new ChatClientThread(this, socket);
thread = new Thread(this);
thread.start();
public void run()
while (thread != null) {
String fromUser;
try{
while((fromUser = input.readLine())!= null)
System.out.println("Client wasreading a data from User, and");
output.println(fromUser);
output.flush();
System.out.println("Client has written a data to Server");
catch(IOException ioe)
{ System.out.println("Sending to server error: " + ioe.getMessage());
stop();
etc.
Here is a piece of codes for reading data from the Client Socket in the ChatServer Class (Server Side socket):
public void run()
{ System.out.println("Server Thread " + clientPort + " running.");
while (true)
{ try
{ //server.handle(clientPort, input.readLine());
System.out.println("Server is reading data from Client, wait...");
String fromUser = input.readLine();
//while((fromUser = input.readLine()) != null)
System.out.println("Server received a message on " + clientPort + ".");
catch(IOException ioe)
{ System.out.println(clientPort + " ERROR reading: " + ioe.getMessage());
server.remove(clientPort);
stop();
etc. Please advice why the readLine() method hangs; does not read data from the input stream received from the CLIENT? -
Problem trying to read an SSL server socket stream using readByte().
Hi I'm trying to read an SSL server socket stream using readByte(). I need to use readByte() because my program acts an LDAP proxy (receives LDAP messages from an LDAP client then passes them onto an actual LDAP server. It works fine with normal LDAP data streams but once an SSL data stream is introduced, readByte just hangs! Here is my code.....
help!!! anyone?... anyone?
1. SSL Socket is first read into " InputStream input"
public void run()
Authorization auth = new Authorization();
try {
InputStream input = client.getInputStream();
while (true)
{ StandLdapCommand command;
try
command = new StandLdapCommand(input);
Authorization t = command.get_auth();
if (t != null )
auth = t;
catch( SocketException e )
{ // If socket error, drop the connection
Message.Info( "Client connection closed: " + e );
close( e );
break;
catch( EOFException e )
{ // If socket error, drop the connection
Message.Info( "Client connection close: " + e );
close( e );
break;
catch( Exception e )
//Way too many of these to trace them!
Message.Error( "Command not processed due to exception");
close( e );
break;
//continue;
processor.processBefore(auth, command);
try
Thread.sleep(40); //yield to other threads
catch(InterruptedException ie) {}
catch (Exception e)
close(e);
2 Then data is sent to an intermediate function
from this statement in the function above: command = new StandLdapCommand(input);
public StandLdapCommand(InputStream in) throws IOException
message = LDAPMessage.receive(in);
analyze();
Then finally, the read function where it hangs at "int tag = (int)din.readByte(); "
public static LDAPMessage receive(InputStream is) throws IOException
* LDAP Message Format =
* 1. LBER_SEQUENCE -- 1 byte
* 2. Length -- variable length = 3 + 4 + 5 ....
* 3. ID -- variable length
* 4. LDAP_REQ_msg -- 1 byte
* 5. Message specific structure -- variable length
DataInputStream din = new DataInputStream(is);
int tag = (int)din.readByte(); // sequence tag// sequence tagI suspect you are actually getting an Exception and not tracing the cause properly and then doing a sleep and then getting another Exception. Never ever catch an exception without tracing what it actually is somewhere.
Also I don't know what the sleep is supposed to be for. You will block in readByte() until something comes in, and that should be enough yielding for anybody. The sleep is just literally a waste of time. -
No exception is thrown when my server socket dies
I have a server application running on sunOS 5.7.
To this I have both Windows and SunOS clients connected via TCP/IP. (Server built with jdk 1.2.2 and client with 1.3.0)
If the Server socket dies an exception is thrown in the windows clients but not in the sunOS client.
I need the exception to be thrown in the sunOS as well.
Is there anybody who knows how to get this done?
Thanks in advance.
/HenrikYou could poll the connection to see if its there.
If you want the client to register the event then have your client create a sort of listener of your own when it connects. By 'sort of listener' I mean extend the thread class and have it check the connection is not null every n seconds. If it is null then raise the exception yourself.
Would this do it?
Rob.
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