Simultaneously request to servlet and causing duplicate trx_id

Hi,
I have a servlet which will handle all the request from external.
That servlet is responsible to insert the request into database by copy a record which already created in one of the table.
My problem is when two requests are coming simultaneously with same trx id, I will hv error of duplicate key.(Note, I assume external party send duplicate request with same trx_id in the same time)
I hv tried to synchonize the method of insert record but seems it does not work. The duplicate primary key error still occurs.
Anyone hv any idea how to solve it? Any suggestion is appreaciate.
Thanks.

I did not duplicate record. After it is moving to another table, the currect record will b deleted. As I know we need to change our database design by using foreign key. However the application now is sitting in production and I could not juz change it like that. It will involve others application as well.
Now my question is how I can ensure each table onli can handle one request per time. As we know synchonize method is to lock the method and others request is not allow to enter the record. But why for my case, even I use synchonize method but others request still can access the method in the same time?

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[svn:fx-trunk] 21141: Bug: 2780176 - Logging and logging out multiple times in LCDS can cause duplicate session detected errors .

Revision: 21141
Revision: 21141
Author:   [email protected]
Date:     2011-04-26 06:40:39 -0700 (Tue, 26 Apr 2011)
Log Message:
Bug: 2780176 - Logging and logging out multiple times in LCDS can cause duplicate session detected errors.
QA: Yes
Doc: No
Checkintests: Pass
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Using database connection in a servlet and get errors after 8 hours

Hey,
I'm running a poker script using applet/servlets and it works great. But for some reason about about 8 hours that database layer stops working. At first I thought it was the connections to mySQL that were timing out (because im using connection pooling) but after turning pooling off (I now create the connection each time) I'm still seeing that same error (I can create a connection but when I do an action ex. like a select statment I get an error). What i'm wondering could it be that the driver I load with Class.forName() some how unloads it's self after x amount of time not being used? Not sure if that is it but if anyone could give me some insight that would be great. The Error i recieve is below:
INFO: Database Event:DatabaseController: Error executing database query.
ERROR: Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.net.SocketException
MESSAGE: Software caused connection abort: recv failed
STACKTRACE:
java.net.SocketException: Software caused connection abort: recv failed
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.read(Unknown Source)
     at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:104)
     at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:144)
     at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:172)
     at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1839)
     at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2288)
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2784)
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     at com.mysql.jdbc.Connection.execSQL(Connection.java:2370)
     at com.mysql.jdbc.Connection.execSQL(Connection.java:2297)
     at com.mysql.jdbc.Statement.executeQuery(Statement.java:1183)
     at com.softnet.database.DatabaseController.executeDatabaseQuery(DatabaseController.java:190)
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I know the query is good because it works all other times just not after about 8 hours.
--Z3r0CooL

Hey,
Thanks for the responces. For the connection pooling I would open 5 connections and keep them open. So i though maybe after 8 hours after not being used they would timeout. Thats why i turned off conection pooling and create a new connection each time. Anyways i'll post the code below incase i made a mistake somewhere.
package com.softnet.database;
/************************ DatabaseControler **************************/
import java.sql.*;
import java.util.*;
import com.softnet.database.DatabaseConnectionPool;
import com.softnet.database.DatabaseSettings;
public class DatabaseController
implements DatabaseListener
     //Used to make sure the database driver is loaded
     private boolean databaseDriverState = false;
     //Used to store a database connection
     private Connection databaseConnection = null;
     //If to user connection pooling or not
     private boolean useConnectionPooling = false;
     //Used to hold the connection pool varible
     private DatabaseConnectionPool connectionPool = null;
     //Used to store database settings
     private DatabaseSettings databaseSettings;
     //Used to hold the DatabaseController listeners
     private List databaseControllerListeners = new ArrayList();
     //min number of connections for connection pool
     private int minNumberOfConnections = 1;
     //max number of connections for connection pool -1 is unlimited
     private int maxNumberOfConnections = -1;
     //DatabaseController Constructors
     public DatabaseController(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
          databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
     public DatabaseController(DatabaseSettings databaseSettings, boolean useConnectionPooling, int minNumberOfConnections, int maxNumberOfConnections)
          this.databaseSettings = databaseSettings;
          this.useConnectionPooling = useConnectionPooling;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          if(useConnectionPooling == true)
               connectionPool = new DatabaseConnectionPool(databaseSettings, minNumberOfConnections, maxNumberOfConnections);
               connectionPool.addDatabaseListener(this);
          else
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
     public DatabaseController() {}
     //Database Settings Get/Set
     public DatabaseSettings getDatabaseSettings()
          return databaseSettings;
     public void setDatabaseSettings(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
     //Connection Pooling Get/Set
     public boolean getConnectionPooling()
          return useConnectionPooling;
     public void setConnectionPooling(boolean useConnectionPooling, int minNumberOfConnections, int maxNumberOfConnections)
          this.useConnectionPooling = useConnectionPooling;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          if(useConnectionPooling == true)
               if(connectionPool == null)
                    connectionPool = new DatabaseConnectionPool(databaseSettings, minNumberOfConnections, maxNumberOfConnections);
                    connectionPool.addDatabaseListener(this);
          else
               if(connectionPool != null)
                    connectionPool.destroyConnections();
                    connectionPool.removeDatabaseListener(this);
                    connectionPool = null;
     //Return if there connected
     public boolean isConnected()
          boolean isConnected;
          if(databaseConnection != null)
               isConnected = true;
          else
               isConnected = false;
          return isConnected;
     //Used to connect to database or get a connection for the connection pool
     public void connect()
          if(databaseDriverState == false)
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //If we dont have a current connection, make one
          if(databaseConnection == null && databaseDriverState == true)
               if(useConnectionPooling == false)
                    try
                         databaseConnection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                    catch (SQLException sqle)
                         //Raise event
                         raiseDatabaseEvent("DatabaseController: Error connecting to database. \nERROR: " + sqle.getMessage());
                         databaseConnection = null;
               else
                    databaseConnection = connectionPool.getConnection();
     //Used to disconnect from the database or give back the connection to the connection pool
     public void disconnect()
          if(databaseConnection != null)
               if(useConnectionPooling == false)
                    try
                         //Close DB Connection
                         databaseConnection.close();
                    catch(SQLException ignore) {}
                    finally
                         databaseConnection = null;
               else
                    connectionPool.returnConnection(databaseConnection);
                    databaseConnection = null;
     public ResultSet executeDatabaseQuery(String sSQL)
          ResultSet databaseResult = null;
          if(databaseConnection != null)
               try
                    Statement databaseStatement = databaseConnection.createStatement();
                    databaseResult = databaseStatement.executeQuery(sSQL);
               catch(SQLException sqle)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error executing database query.\nSQL: " + sSQL + "\nERROR: " + sqle.getMessage());
          return databaseResult;
     public int executeDatabaseUpdate(String sSQL)
          int rowsAffected = -1;
          if(databaseConnection != null)
               try
                    Statement databaseStatement = databaseConnection.createStatement();
                    rowsAffected = databaseStatement.executeUpdate(sSQL);
               catch(SQLException sqle)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error executing database update.\nSQL: " + sSQL + "\nERROR: " + sqle.getMessage());
          return rowsAffected;
     //Used to load the Database Driver
     private boolean loadDatabaseDriver(String databaseDriver)
          boolean driverLoaded;
          if(databaseDriver.equals("") == false)
               try
                    //Load Database Driver
                    Class.forName(databaseDriver).newInstance();
                    driverLoaded = true;
               catch (Exception e)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error loading database driver. \nERROR: " + e.getMessage());
                    driverLoaded = false;
          else
               driverLoaded = false;
          return driverLoaded;
     //Wrap the DatabaseConnectionPool Error to the DatabaseController
     public void databaseEventOccurred(DatabaseEvent de)
          raiseDatabaseEvent(de.getErrorMessage());
     //Event Handling Code
     //Used to add database listeners (Its sync'd so you can change the listeners when firing an event)
public synchronized void addDatabaseListener(DatabaseListener databaseControllerListener)
databaseControllerListeners.add(databaseControllerListener);
//Used to remove a listener from the list (Its sync'd so you can change the listeners when firing an event)
public synchronized void removeDatabaseListener(DatabaseListener databaseControllerListener)
databaseControllerListeners.remove(databaseControllerListener);
//Used to send the raise event to the listeners
private synchronized void raiseDatabaseEvent(String databaseError)
DatabaseEvent databaseEvent = new DatabaseEvent(this, databaseError);
Iterator listeners = databaseControllerListeners.iterator();
while(listeners.hasNext())
     DatabaseListener listener = (DatabaseListener) listeners.next();
listener.databaseEventOccurred(databaseEvent);
/********************* DatabaseConnectionPool **************/
package com.softnet.database;
import java.io.*;
import java.sql.*;
import java.util.*;
import com.softnet.database.*;
import com.softnet.database.DatabaseSettings;
public class DatabaseConnectionPool
     //min number of connections
     private int minNumberOfConnections = 1;
     //max number of connections -1 is unlimited
     private int maxNumberOfConnections = -1;
     //Store the connections
     protected Hashtable databaseConnections = null;
     //Database Info
     protected DatabaseSettings databaseSettings;
     //to hold Driver state
     private boolean databaseDriverState = false;
     //To hold connection checker
     private DatabaseConnectionCheck connectionChecker = null;
     //Used to hold the DatabaseConnectionPool listeners
     private List databaseConnectionPoolListeners = new ArrayList();
     public DatabaseConnectionPool(DatabaseSettings databaseSettings, int minNumberOfConnections, int maxNumberOfConnections)
          this.databaseSettings = databaseSettings;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          //Load Driver
          databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //Create connection
          createConnections();
     public DatabaseConnectionPool(int minNumberOfConnections, int maxNumberOfConnections)
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
     //Database Settings Get/Set
     public DatabaseSettings getDatabaseSettings()
          return databaseSettings;
     public void setDatabaseSettings(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
     //Driver State Get
     public boolean getDatabaseDriverState()
          return databaseDriverState;
     public void createConnections()
          if(databaseDriverState == false)
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //Create all connections and load the minimum in the Hashtable
          if(databaseConnections == null)
               if(databaseDriverState == true && minNumberOfConnections != 0)
                    databaseConnections = new Hashtable();
                    for(int i = 0; i < minNumberOfConnections; i++)
                         try
                              databaseConnections.put(DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword()), Boolean.FALSE);
                         catch(SQLException sqle)
                              //Problem break loop and destroy any connections
                              destroyConnections();
                              //Raise event
                              raiseDatabaseEvent("DatabaseConnectionPool: Error creating database connections. \nERROR: " + sqle.getMessage());
                              break;
          //If no connection check exists create one
          if(connectionChecker == null)
               connectionChecker = new DatabaseConnectionCheck(this);
               connectionChecker.start();
     public Connection getConnection()
          Connection connection = null;
          boolean errorWithConnection = false;
          Enumeration connections = databaseConnections.keys();
          synchronized (databaseConnections)
               while(connections.hasMoreElements())
                    errorWithConnection = false;
                    connection = (Connection) connections.nextElement();
                    Boolean state = (Boolean) databaseConnections.get(connection);
                    //If connection is not used, use it.
                    if(state == Boolean.FALSE)
                         try
                              connection.setAutoCommit(true);
                         catch(SQLException e)
                              //Problem with connection remove connection and replace it
                              databaseConnections.remove(connection);
                              try
                                   connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                              catch(SQLException sqle)
                                   errorWithConnection = true;
                         if(errorWithConnection == false)
                              // Update the Hashtable to show this one's taken
                              databaseConnections.put(connection, Boolean.TRUE);
                              // Return the connection
                              return connection;
               //All connections being used check to max to see if we can make a new one
               if(maxNumberOfConnections == -1 || maxNumberOfConnections > databaseConnections.size())
                    try
                         connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                    catch(SQLException sqle)
                         errorWithConnection = true;
                    if(errorWithConnection == false)
                         databaseConnections.put(connection, Boolean.TRUE);
                         return connection;
          //If not connections free and max connections reached wait for a free connection
          return getConnection();
     public void returnConnection(Connection connection)
          boolean errorWithConnection = false;
          //Make sure connection still works
          try
               connection.setAutoCommit(true);
          catch(SQLException e)
               //Problem with connection remove connection and replace it
               databaseConnections.remove(connection);
               try
                    connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
               catch(SQLException sqle)
                    errorWithConnection = true;
          if(errorWithConnection == false)
               databaseConnections.put(connection, Boolean.FALSE);
     public void destroyConnections()
          Connection connection = null;
          if(databaseConnections != null)
               //Close all connections
               Enumeration connections = databaseConnections.keys();
               while (connections.hasMoreElements())
                    connection = (Connection) connections.nextElement();
                    try
                         connection.close();
                    catch(SQLException ignore) {}
               //Free up hashtable
               databaseConnections = null;
     private boolean loadDatabaseDriver(String databaseDriver)
          boolean driverLoaded;
          if(databaseDriver.equals("") == false)
               try
                    //Load Database Driver
                    Class.forName(databaseDriver);
                    driverLoaded = true;
               catch (ClassNotFoundException cnfe)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error loading database driver. \nERROR: " + cnfe.getMessage());
                    driverLoaded = false;
          else
               driverLoaded = false;
          return driverLoaded;
     //Event Handling Code
     //Used to add database listeners (Its sync'd so you can change the listeners when firing an event)
public synchronized void addDatabaseListener(DatabaseListener databaseConnectionPoolListener)
databaseConnectionPoolListeners.add(databaseConnectionPoolListener);
//Used to remove a listener from the list (Its sync'd so you can change the listeners when firing an event)
public synchronized void removeDatabaseListener(DatabaseListener databaseConnectionPoolListener)
databaseConnectionPoolListeners.remove(databaseConnectionPoolListener);
//Used to send the raise event to the listeners
private synchronized void raiseDatabaseEvent(String databaseError)
DatabaseEvent databaseEvent = new DatabaseEvent(this, databaseError);
Iterator listeners = databaseConnectionPoolListeners.iterator();
while(listeners.hasNext())
     DatabaseListener listener = (DatabaseListener) listeners.next();
listener.databaseEventOccurred(databaseEvent);
class DatabaseConnectionCheck extends Thread
     private DatabaseConnectionPool connectionPool;
     DatabaseConnectionCheck(DatabaseConnectionPool connectionPool)
          this.connectionPool = connectionPool;
     public void run()
          try
               while(true)
                    //check threads every 30 seconds
                    this.sleep(300000);
                    if(connectionPool.databaseConnections != null)
                         Connection connection = null;
                         Enumeration connections = connectionPool.databaseConnections.keys();
                         synchronized (connectionPool.databaseConnections)
                              while(connections.hasMoreElements())
                                   connection = (Connection) connections.nextElement();
                                   Boolean state = (Boolean) connectionPool.databaseConnections.get(connection);
                                   //If connection is not used, use it.
                                   if(state == Boolean.FALSE)
                                        try
                                             connection.setAutoCommit(true);
                                        catch(SQLException e)
                                             //Problem with connection remove connection and replace it
                                             connectionPool.databaseConnections.remove(connection);
                                             try
                                                  connection = DriverManager.getConnection(connectionPool.databaseSettings.getDatabaseURL(), connectionPool.databaseSettings.getUserName(), connectionPool.databaseSettings.getUserPassword());
                                             catch(SQLException sqle)
                                                  connection = null;
                                             // Update the Hashtable with new connection if its not null
                                             if(connection != null)
                                                  connectionPool.databaseConnections.put(connection, Boolean.FALSE);
          catch(InterruptedException ignored) {}
Basicly the why it works is the connection pool hold the database connections. When the user needs a connection they use the database controller to request a connection (By create a instance and called the connect() method) and the connection is either created or grabed from the connection pool. After the user is done with the connection they call the disconnect() method which closes the connection or returns it to the connection pool.
--Z3r0CooL

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Connection: Keep-Alive
Cookie: JSESSIONID=nGrHKG6SWG2Tg2Z515GzlxhJFRw1pdX7Gm3F1YYcL23ppXHy3kgj!-2050079672
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oracle.adf.view.rich.render.RichRenderer.encodeAll(RichRenderer.java:1050)
org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(CoreRenderer.java:224)
org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(UIXComponentBase.java:763)
org.apache.myfaces.trinidad.component.UIXComponentBase.__encodeRecursive(UIXComponentBase.java:1351)
org.apache.myfaces.trinidad.component.UIXComponentBase.encodeAll(UIXComponentBase.java:783)
javax.faces.component.UIComponent.encodeAll(UIComponent.java:942)
com.sun.faces.application.ViewHandlerImpl.doRenderView(ViewHandlerImpl.java:273)
com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:204)
javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:189)
org.apache.myfaces.trinidadinternal.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:188)
oracle.adfinternal.view.faces.lifecycle.LifecycleImpl._renderResponse(LifecycleImpl.java:652)
oracle.adfinternal.view.faces.lifecycle.LifecycleImpl._executePhase(LifecycleImpl.java:243)
oracle.adfinternal.view.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:203)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
oracle.adf.model.servlet.ADFBindingFilter.doFilter(ADFBindingFilter.java:181)
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
oracle.adfinternal.view.faces.webapp.rich.RegistrationFilter.doFilter(RegistrationFilter.java:85)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl$FilterListChain.doFilter(TrinidadFilterImpl.java:278)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._invokeDoFilter(TrinidadFilterImpl.java:238)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:195)
org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:138)
org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3496)
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
weblogic.security.service.SecurityManager.runAs(Unknown Source)
weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2180)
weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2086)
weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1406)
weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
weblogic.work.ExecuteThread.run(ExecuteThread.java:173)
========================
Application is developed with ADF 11g (11.1.1.0.2) and only refreshes a graph periodically via af:poll.
Any ideas what I can do to analyze and resolve the problem?
regards
Peter

repost

JSP Servlet and convert the result set of an SQL Query To XML file

Hi all
I have a problem to export my SQL query is resulty into an XML file I had fixed my servlet and JSP so that i can display all the records into my database and that the goal .Now I want to get the result set into JSP so that i can create an XML file from that result set from the jsp code.
thisis my servlet which will call the jsp page and the jsp just behind it.
//this is the servlet
import java.io.*;
import java.lang.reflect.Array;
import java.sql.*;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.naming.*;
import javax.sql.*;
public *class *Campaign *extends *HttpServlet
*private* *final* *static* Logger +log+ = Logger.+getLogger+(Campaign.*class*.getName());
*private* *final* *static* String +DATASOURCE_NAME+ = "jdbc/SampleDB";
*private* DataSource _dataSource;
*public* *void* setDataSource(DataSource dataSource)
_dataSource = dataSource;
*public* DataSource getDataSource()
*return* _dataSource;
*public* *void* init()
*throws* ServletException
*if* (_dataSource == *null*) {
*try* {
Context env = (Context) *new* InitialContext().lookup("java:comp/env");
_dataSource = (DataSource) env.lookup(+DATASOURCE_NAME+);
*if* (_dataSource == *null*)
*throw* *new* ServletException("`" + +DATASOURCE_NAME+ + "' is an unknown DataSource");
} *catch* (NamingException e) {
*throw* *new* ServletException(e);
protected *void *doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
Connection conn = *null*;
*try* {
conn = getDataSource().getConnection();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("select post_id,comments,postname from app.posts");
// out.println("Le résultat :<br>");
ArrayList <String> Lescomments= *new* ArrayList<String>();
ArrayList <String> Lesidentifiant = *new* ArrayList<String>();
ArrayList <String> Lesnoms = *new* ArrayList <String>();
*while* (rs.next()) {
Lescomments.add(rs.getString("comments"));
request.setAttribute("comments",Lescomments);
Lesidentifiant.add(rs.getString("post_id"));
request.setAttribute("id",Lesidentifiant);
Lesnoms.add(rs.getString("postname"));
request.setAttribute("nom",Lesnoms);
rs.close();
stmt.close();
*catch* (SQLException e) {
*finally* {
*try* {
*if* (conn != *null*)
conn.close();
*catch* (SQLException e) {
// les paramètres sont corrects - on envoie la page réponse
getServletContext().getRequestDispatcher("/Campaign.jsp").forward(request,response);
}///end of servlet
}///this is the jsp page called
<%@ page import="java.util.ArrayList" %>
<%
// on récupère les données
ArrayList nom=(ArrayList)request.getAttribute("nom");
ArrayList id=(ArrayList)request.getAttribute("id");
ArrayList comments=(ArrayList) request.getAttribute("comments");
%>
<html>
<head>
<title></title>
</head>
<body>
Liste des campagnes here i will create the xml file the problem is to display all rows
<hr>
<table>
<tr>
</tr>
<tr>
<td>Comment</td>
<td>
<%
for( int i=0;i<comments.size();i++){
out.print("<li>" + (String) comments.get(i) + "</li>\n");
}//for
%>
</tr>
<tr>
<td>nom</td>
<td>
<%
for( int i=0;i<nom.size();i++){
out.print("<li>" + (String) nom.get(i) + "</li>\n");
}//for
%>
</tr>
<tr>
<td>id</td>
<td>
<%
for( int i=0;i<id.size();i++){
out.print("<li>" + (String) id.get(i) + "</li>\n");
}//for
%>
</tr>
</table>
</body>
</html>
This is how i used to create an XML file in a JSP page only without JSP/SERVLET concept:
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
// Identify a carriage return character for each output line
int iLf = 10;
char cLf = (*char*)iLf;
// Create a new empty binary file, which will content XML output
File outputFile = *new* File("C:\\Users\\user\\workspace1\\demo\\WebContent\\YourFileName.xml");
//outputFile.createNewFile();
FileWriter outfile = *new* FileWriter(outputFile);
// the header for XML file
outfile.write("<?xml version='1.0' encoding='ISO-8859-1'?>"+cLf);
try {
// Define connection string and make a connection to database
Connection conn = DriverManager.getConnection("jdbc:derby://localhost:1527/SAMPLE","app","app");
Statement stat = conn.createStatement();
// Create a recordset
ResultSet rset = stat.executeQuery("Select * From posts");
// Expecting at least one record
*if*( !rset.next() ) {
*throw* *new* IllegalArgumentException("No data found for the posts table");
outfile.write("<Table>"+cLf);
// Parse our recordset
// Parse our recordset
*while*(rset.next()) {
outfile.write("<posts>"+cLf);
outfile.write("<postname>" + rset.getString("postname") +"</postname>"+cLf);
outfile.write("<comments>" + rset.getString("comments") +"</comments>"+cLf);
outfile.write("</posts>"+cLf);
outfile.write("</Table>"+cLf);
// Everything must be closed
rset.close();
stat.close();
conn.close();
outfile.close();
catch( Exception er ) {
%>

Please state your problem that you are having more clearly so we can help.
I looked at your code I here are a few things you might consider:
It looks like you are putting freely typed-in comments from end-users into an xml document.
The problem with this is that the user may enter characters in his text that have special meaning
to xml and will have to be escaped correctly. Some of these characters are less than character, greater than character and ampersand character.
You may also have a similiar problem displaying them on your JSP page since there may be special characters that JSP has.
You will have to read up on how to deal with these special characters (I dont remember what the rules are). I seem to recall
if you use CDATA in your xml, you dont have to deal with those characters (I may be wrong).
When you finish writing your code, test it by entering all keyboard characters to make sure they are processed, stored in the database,
and re-displayed correctly.
Also, it looks like you are putting business logic in your JSP page (creating an xml file).
The JSP page is for displaying data ONLY and submitting back to a servlet. Put all your business logic in the servlet. Putting business logic in JSP is considered bad coding and will cause you many hours of headache trying to debug it. Also note: java scriptlets in a JSP page are only run when the JSP page is compiled into a servlet by java. It does not run after its compiled and therefore you cant call java functions after the JSP page is displayed to the client.

Maximum Number of Simultaneous Requests

I want to update the Maximum Number of Simultaneous Requests
from 4 to 6 or 8. A restart of ColdFusion Application Server is
required for changes to take effect. Has anyone experienced
problems with the change not taking effect and/or causing the
service to not restart.
This has not happened. Being precautionary. The reason for
the question is that I made a change previously to the Max Heap
size from 1023 to 1535 in CF Admin, but when I attempted to restart
the CF service it would not. Finally had to change the Max Heap in
jvm.config back to 1023. Unsure why that would not accept it. The
variable is that the service is running with a non-admin user ID on
the server. Thoughts?

The prevailing wisdom from Adobe for simultaneous requests is
very wrong and inaccurate. First off, editing the simultaneous
requests in the CFAdmin is safe to do. Editing your JVM settings
with the CFAdmin is very dangerous on Linux because the CF Admin
code can mangle the xml file. I'm not sure if this is true on
Windows.
Now back to the simultaneous requests issue. If you have high
traffic and enough server processing power you can greatly increase
the request number. We currently run our CFMX 7.02 servers set to
100 simultaneous requests. And yes we've been maxed out at that
level. We see over 1.5 million page views per day on a single cf
server with only one instance of CF. As of today we switched to a
load balanced setup and split the load across two servers. The
reason we went load balanced is that we're expecting to more than
double our traffic. Anyways, the number of simultaneous requests
can be much higher than the 'General Wisdom' at Adobe.
Oh yeah, I almost forgot. I've seen the new setting for
simultaneous requests take effect with out having to restart CFMX.
Cheers,

User Authentication using Servlet and JSp

Hi,
I am developing a web app where i need to implement user Authentication to allow members to view and upload files on a certain directory say /data
For this i am using a servlet as a controller which then forwads request to other jsps/servlets based on user response. I tried using servlet mapping in web.xml so that all browser requests would be directed to controller servlet and would branch from there on. However the problem all RequestDispatcher.forward() requests redirected to the servlet putting it in a loop.
Is there another way to achieve this. (Apart from using form-based Basic Authentication).
I am using Resin 1.2.8 servlet/jsp container.
Any response as soon as possible would be appreciated.
Thanks,
Kushagra

RequestDispatcher.forward() cause the HTTP request to be sent through the request processing flow as if the original request for the resource being forwarded to.
It seems the servlet mapping you are talking about in web.xml should be made more specific. i.e. the mapping should be such that only your so called controller servlet will match up.
You might want to specify the mapping for the controller servlet to be noticeably/effectively different from the mapping for other servlets and JSPs.

Problem for getting the real path using one servlet and one jsp page

I have one tomcat machine and several virtual domains. Eahc virtual domain has one realpath in the disc.
I am using one servlet and one jsp page for using this servlet.
my purpose is to load, using the servlet , the real path for the domains (eahc domain has its path).
for this i make this:
the servlet code is this:
package utils.ticker;
import java.io.*;
import java.io.File;
import java.io.IOException;
import java.net.*;
import java.util.*;
import java.text.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class Edicion extends HttpServlet{
public Edicion() {
public String cc(){
ServletContext myContext= getServletContext();
String abspath = myContext.getRealPath("/");
//here i want to return the real path
return abspath;
public static void main(String args[]){
and the jsp page is:
<%@ page import="utils.ticker.*" %>
<jsp:useBean id="tick" class="utils.ticker.Edicion" scope="session"/>
<html><head><body>
<%
tick.cc();
%>
</body></head></html>
But this produces one error, NullPointerException and dont shows me the real path.
Can anyone help me?
thanks

i have put this into one sevlet:
package utils.ticker;
import javax.servlet.ServletContext;
public class Edicion{
private ServletContext myContext;
public Edicion(ServletContext myContext) {
this.myContext = myContext;
public String getCC(){
return myContext.getRealPath("/");
and in the jsp page this:
<%@ page contentType="text/html; charset=iso-8859-1" language="java" import="java.sql.*"%>
<%@ page import="utils.ticker.*" %>
<jsp:useBean id="tick" class="utils.ticker.Edicion" scope="session"/>
<html><head><body>
<%=tick.getCC()%>
</body></head></html>
but appear this error in the tomcat.
Can you, please, help me. i am trying to solve this during one week and i am desesperate.
Thanks.
ERROR:
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: class utils.ticker.Edicion : java.lang.InstantiationException: utils.ticker.Edicion
     at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:248)
     at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:260)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:432)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:386)
     at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:534)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:530)
     at java.lang.Thread.run(Thread.java:536)
root cause
javax.servlet.ServletException: class utils.ticker.Edicion : java.lang.InstantiationException: utils.ticker.Edicion
     at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:533)
     at org.apache.jsp.pruebas_jsp._jspService(pruebas_jsp.java:72)
     at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:204)
     at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:260)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
     at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
     at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:432)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:386)
     at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:534)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:530)
     at java.lang.Thread.run(Thread.java:536)
Apache Tomcat/4.1.18

Servlets and multiple JDBC connections...

Hi Guru's
I want to perform multiple JDBC queries simultaneously from my servlet. Let's say I have a connection pool containing JDBC connections. Now what I want to do is to use each of this connections simultaneously to perform queries in parallel.
What is the best way to do this??? create multiple threads, one for each query, and then collate results when all threads are finished???
Has anyone does this before or know of any links or samples which I can look at??
your help much appreciated...
Many Thanks

Thanks but further questions....
But take care:
multithreading might only work parallel if there are
multiple processors - otherwise the thread fragments
will be processed one after the other until they are
finished.I agree. My server has multiple processors hence multi-threading.
Why do you need to perform the queries
simultaneously?
wouldn't it work too when you perform the queries one
after the other?To speed up performance. Sequential processing is too slow at the moment.
Hope you don't try doing so inside one single
database...yes inside a single databse.
Do you have any links to sample example etc..??? Importantly are you aware of any issues when one does this type of multi-threading from servlet. i.e does it clash with servlet's threading model etc...
I am aware of how servlets multithread requests and am quite familiar with them. Just wanted some examples on multithreading JDBC connections from servlets and how I can wait for all threads to finish before collecting results....also wanted to make sure that there are no other issues....
further help will be much appreciated.....

Troubles with simultaneous requests

(sorry for my poor english)
I have a problem with web sites generated with servlets
- linux server with apache & jserv & mysql.
All web sites are generated with the same servlet and refer to the same database. They are identified with an index
(like www.site.com/servlet/showsite?site=12)
with 5 sites : ok.
with 50 sites :
sometimes, when many users access simultaneously several sites, there is a mix of datas (menu of site #1 with pages of site #12).
Is it jserv wrong settings, or else ??
thanks

i think that you use instance variables in servlet class, or you test your servlet by making multiple request from the same session (this could happen eg. if you use ctrl-n in ie to create new window), or there may be something like that
i have used jserv a year ago (wich is quite a time) but i dont remember that i ever had major problem like yours with it
perhaps you should post the pieces of servlet code without uninteresting parts ...
jano

How to get the query values from the url in a servlet and pass them to jsp

ok..this is the situation...
all applications are routed through a login page...
so if we have a url like www.abc.com/appA/login?param1=A&param2=B , the query string must be passed onto a servlet(which is invoked before the login page is displayed)..the servlet must process the query string and then should pass all those values(as hidden values) to the login jsp..then user enters username and pswd, then there should be another servlet which takes all the hidden values of jsp and also username and pswd, authenticates the user and sends the control back to that particular application along with the hidden values...
so i need help on how to parse the query string from the original url in the servlet, pass it out to jsp, and then pass it back to the servlet and back to the original application...damnn...any help would be greatly appreciated...thanks

ok..this is the situation...Sounds like you have a bad design on your hands.
You're going to send passwords in a GET request as clear text? Nice security there.
Why not start with basic security and work your way up?
%

How can I Delete a MobileMe Email Account and Kill Duplicate Messages?

When I select "All Inboxes" on my iPhone 4s, I see duplicates of each and every message I receive. Furthermore, the duplicate can't be deleted and I get an error message informing so! I suspect this phenomenon is occurring because I have both an iCloud and a MobileMe account. I want to cancel the MobileMe one.
Here's the deal:
My iPhone 4s lists three email accounts, including a "MobileMe" one that I want to delete because I believe it is delivering duplicate messages. However, I can't seem to figure out how to delete the MobileMe's email account or, for that matter, MobileMe itself. Apple support screens refer to cancelling a MobileMe account but are not clear on how to actually do it.
1. On the iPhone 4s, I click on the "Mail" icon at the bottom of the screen
2. On a screen under the heading "Mailboxes," under "Inboxes," there are two that read exactly the same (I think one is iCloud and the other MobileMe).
3. On the same screen, under "Accounts," I see an iCloud account logo, a Bellsouth/Yahoo account logo and a MobileMe account logo.
4. I want to keep the iCloud and Bellsouth/Yahoo accounts but delete the MobileMe one but I can find no way on this screen or any other iPhone 4s screen to do so. Nor do I see any path to do so in iTunes. And the MobileMe account doesn't even show up in the Apple email app on the laptop to which I sync my iPhone.
If I go to www.me.com and log into my MobileMe account, there is no apparent way to disable, delete or otherwise cancel it. Why?
I am convinced that the simultaneous presence of both iCloud and MobileMe accounts is responsible for the double email messages when I select to view "All inboxes" on my iPhone. (A workaround is to simply select just one of the accounts, say, the iCloud one. Then I see only one copy of each message. That's OK but surely there is some way to kill off this redundant MobileMe account AND the duplicate messages, yes???

First, thanks for the reply. And, I believe you are exactly right that the names are the same. However, when I go (on my iPhone) as you suggest to "Settings," "Mail, Contacts, Calendars," only two accounts are showing; my Mac account and my Bellsouth one. If I select either, I get an option to delete but the duplicate "MobileMe" account does not appear. It only shows up, as described above, if I:
1. On the iPhone 4s, I click on the "Mail" icon at the bottom of the screen
2. On a screen under the heading "Mailboxes," under "Inboxes," there are two that read exactly the same (I think one is iCloud and the other MobileMe).
3. On the same screen, under "Accounts," I see an iCloud account logo, a Bellsouth/Yahoo account logo and a MobileMe account logo.
It's nutso, I admit, but true. Any other suggestions would be most welcome.

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