Q: TCP Connections from an Applet

Hi,
is it possible to build a tcp socket connection on a specified port on the webserver with an unsigned applet?
as example: the applet is stored on the webserver, port 80.
somebody calls the applet with a webbrowser, and another connection, maybe port 7777, is build back to the webserver?
I just have to know if it is possible.
thanks for information

Yes

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How do i make http connection from an applet to a servlet

i am not able to make a http connection from the applet to servlet
my code for servlet is as follows
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class newDatabaseServlet extends HttpServlet {
//      Connection con;
// Statement stmt;
     public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
          resp.setContentType("text/content");
          System.out.println("megha");
          String mthd[] = req.getParameterValues("event");
          System.out.println(mthd.length);
          System.out.println(mthd);
          System.out.println(req.getQueryString());
          // System.out.println("megha");
PrintWriter fw = new PrintWriter(new FileOutputStream(new File("e:/JRun/servers/default/default-app/mycontent.txt")));
String s = "this text comes from servlet";
fw.print(s);
fw.flush();
          if(mthd[0].equalsIgnoreCase("callEditor")) {
               openEditor(req,resp);
public void openEditor(HttpServletRequest req, HttpServletResponse resp) {
     /* try {
          Class.forName("oracle.jdbc.driver.OracleDriver");
     con = DriverManager.getConnection("jdbc:oracle:thin:@pc6:1521:oradba","test","test");
     catch(Exception e) {
          e.printStackTrace();
          try {
               resp.sendRedirect("/RunApp1.html");
          catch(IOException e) {
               e.printStackTrace();
/*try {
     Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection("jdbc:oracle:thin:@pc6:1521:oradba","test","test");
     catch(Exception e) {
     e.printStackTrace();
     resp.setContentType("text/html");
     PrintWriter output = resp.getWriter();
     try {
stmt = con.createStatement();
String strContent = "select * from edTable where newsid = 2";
ResultSet rs = stmt.executeQuery(strContent);
if(rs.next()) {
               String newsText = rs.getString(2);
/* StringBuffer buf = new StringBuffer();
               buf.append("<B>servlet</B>");
               try {
               resp.sendRedirect("RunApp");
          catch(IOException e) {
               e.printStackTrace();
//               output.println(buf.toString());
//          output.close();
my code for applet is
import javax.swing.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import java.awt.*;
import javax.swing.text.*;
import javax.swing.text.html.*;
public class EdApplet extends JApplet {
public void init() {
     Container c;
     c = getContentPane();
JPanel but = new JPanel();
c.add(but,BorderLayout.NORTH);
final JEditorPane je = new JEditorPane();
JScrollPane jsp = new JScrollPane(je);
HTMLEditorKit ht = new HTMLEditorKit();
je.setEditorKit(ht);
je.setEditable(true);
HTMLDocument mdoc = (HTMLDocument)ht.createDefaultDocument();
StyleSheet mcontext =mdoc.getStyleSheet();
je.setDocument(mdoc);
c.add(jsp,BorderLayout.CENTER);
JPanel bot = new JPanel();
c.add(bot,BorderLayout.SOUTH);
JButton save = new JButton("save");
but.add(save);
String str = getInitialText();
     je.setText(str);
     String servletUrl="http://pc7:8100/servlet/newDatabaseServlet";
try{
               URL servletURL = new URL(servletUrl);
               URLConnection servletConnection = servletURL.openConnection();
          servletConnection.setRequestProperty("event","saveText");
          servletConnection.setDoOutput(true);
          servletConnection.setUseCaches(false);
     catch(Exception e) {
//          je.setText(e.printStackTrace());
     ActionListener lst = new ActionListener() {
          public void actionPerformed(ActionEvent ae) {
               String save = je.getText();
               saveText(save,je);
     save.addActionListener(lst);
//je.setText("<B>this</B>");
//URLConnection servletConnection = null;
/* try {
          String servletUrl="http://pc7:8100/servlet/newDatabaseServlet";
          URL myUrl = new URL(servletUrl);
          servletConnection = myUrl.openConnection();
          servletConnection.setDoOutput(true);
          servletConnection.setUseCaches(false);
     /*     BufferedReader br = new BufferedReader(new InputStreamReader(servletConnection.getInputStream()));
String t = br.readLine();
je.setText(t);
     catch(Exception e) {
          e.printStackTrace();
/* ActionListener lst = new ActionListener() {
          public void actionPerformed(ActionEvent ae) {
               BufferedReader br = new BufferedReader(new InputStreamReader(servletConnection.getInputStream()));
               String t = br.readLine();
je.setText(t);
click.addActionListener(lst);
/*void String changeText(UrlConnection con) {
BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream));
String t = br.readLine();
return t;
public String getInitialText()
     //String me = null;
     URLConnection textConnection = null;
     StringBuffer sb = new StringBuffer();
     try {
               String textUrl="http://pc7:8100/mycontent.txt";
               URL myUrl = new URL(textUrl);
               textConnection = myUrl.openConnection();
               textConnection.setDoInput(true);
               textConnection.setUseCaches(false);
               BufferedReader br = new BufferedReader(new InputStreamReader(textConnection.getInputStream()));
               // me = (String)servletConnection.getContent();
               String s = null;
               while((s = br.readLine())!=null) {
                    sb.append(s);
          catch(Exception e) {
                         e.printStackTrace();
               return sb.toString();
     public void saveText(String saveStr,JEditorPane je) {
          //String saveStr = je.getText();
          //String servletUrl="http://pc7:8100/servlet/newDatabaseServlet?event='saveText'&newsid='2'";
          //String servletGet="http://pc7:8100/servlet/newDatabaseServlet";
          String servletUrl="http://pc7:8100/servlet/newDatabaseServlet";
          //String servletUrl = servletGet + "?"
          //     + URLEncoder.encode("event") + "="
     // + URLEncoder.encode("saveText");
//     je.setText(servletUrl);
          try {
          URL servletURL = new URL(servletUrl);
          URLConnection servletConnection = servletURL.openConnection();
     //     servletConnection.setRequestProperty("event","saveText");
     servletConnection.setRequestProperty(
     "User-Agent","Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)");
          //System.out.println("from applet");
          servletConnection.setDoOutput(true);
          servletConnection.setUseCaches(false);
          //Propertiew prop = new Properties();
     //     prop.put("event","saveText");
          PrintStream out = new PrintStream(servletConnection.getOutputStream());
out.println("event");
out.close();
     catch(IOException e) {
          je.setText(e.toString());
kindly tell me what is the error
what is the best method of doing this
thanking u in anticipation
megha sood

omg O_o
We cannot debug your code, but:
Did you try the servlet directly from your browser? Does it work?
Best regards from Germany,
r.v.

Outgoing TCP connections from VM have very low firewall state idle timeout -- how do you adjust?

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[2] - If you are using WCF based application please have a look at below link:
Reference:
http://code.msdn.microsoft.com/WCF-Azure-NetTCP-Keep-Alive-09f50fd9
[3] - If you are using TCP Sockets then you can also try ServicePointManager.SetTcpKeepAlive(true, 30000, 30000) might be used to do this. TCP Keep-Alive packets will keep the connection from your client to the load balancer open during a long-running HTTP
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i have a applet code as follows that listens for multicast messages. ...
this works fine when i start it in the applet viewer (multicating server is in the same system)
when i access the same through the html pages /// it gives an exception java.security.exception.Accessdenied ..................
any idea to solve this is most appriciated ......
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[/code}

I agree, when you run it in the applet viewer you use a special policy.
http://forum.java.sun.com/thread.jsp?forum=63&thread=524815
second post and last post for the java class file
If that didn't solve your problem than a full trace would be nice:
To turn the full trace on (windows) you can start the java console, to be found here:
C:\Program Files\Java\j2re1.4...\bin\jpicpl32.exe
In the advanced tab you can fill in something for runtime parameters fill in this:
-Djavaplugin.trace=true -Djavaplugin.trace.option=basic|net|security|ext|liveconnect
if you cannot start the java console check here:
C:\Documents and Settings\userName\Application Data\Sun\Java\Deployment\deployment.properties
I think for linux this is somewhere in youruserdir/java (hidden directory)
add or change the following line:
javaplugin.jre.params=-Djavaplugin.trace\=true -Djavaplugin.trace.option\=basic|net|security|ext|liveconnect
for 1.5:
deployment.javapi.jre.1.5.0.args=-Djavaplugin.trace\=true -Djavaplugin.trace.option\=basic|net|security|ext|liveconnect
The trace is here:
C:\Documents and Settings\your user\Application Data\Sun\Java\Deployment\log\plugin...log
I think for linux this is somewhere in youruserdir/java (hidden directory)
Print out the full trace of the exception:
try{...}catch(Exception e){e.printStackTrace();}

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Hi,
How about editing the Maximum non TCP sessions per second per rule setting?
For more information:
http://technet.microsoft.com/en-us/library/dd441028.aspx
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Q: TCP Connections from an Applet

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