Global variable in servlet

Dear Friends,
I have a hashtable(which keeps all user sessions) as a global variable in my login servlet and I have three methods in servlet.
Hashtable sessiontable = new Hashtable();
public synchronized void addSession(HttpSession s)
sessiontable.put(s.getId(), s);
public synchronized void removeSession(String id)
HttpSession tempsession = sessiontable.get(id);
sessiontable.remove(tempsession );
public synchronized HttpSession getSession(String id)
return sessionTable.get(id)
Can u plz help me to figure out whether there will be any synchronization problems.
Best Rehards,
Chamal.

Similar Messages

Global variable in servlet & DBPooling questions

Hello guys,
I used to develop PHP/ASP, and am new to servlet. I have been searching around for a solution ...
With Php, we can get the reference of a global variable in any classes->functions...
How do I do this with servlet ?
And second..I have developed the DB class as below... I set the datasource to be static, so it initializes only once. Is it a good idea? How would you like to improve this class? any comments?
package shop.database;
import javax.sql.DataSource;
import java.sql.*;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.log4j.Logger;
import shop.admin.exception.GeneralException;
public class DdManager {
     static protected Logger logger = Logger.getLogger(DdManager.class);
     private String userName = "root";
private String password = "";
private String hostName = "jdbc:mysql://localhost:3306/shop";
private String database="shop";
     static private DataSource ds;     // set this to be static so all threads share the same job in JVM
     private Statement stmt;
     private Connection conn;
     private ResultSet rs;
     private CallableStatement cs;
public DdManager() {}
* setup the data source and return it
     public static DataSource getDataSource(
          String sDrvName,
          String sUserName,
          String sPwd,
          String connectURI) {
          BasicDataSource ds = new BasicDataSource();
          ds.setDriverClassName( sDrvName );
          ds.setUsername( sUserName );
          ds.setPassword( sPwd );
          ds.setUrl( connectURI );
          ds.setMaxActive( 15 );
          ds.setMaxIdle( 10 );
          ds.setMaxWait( 10000 ); // 10 seconds
          return ds;
     * static init of the class
     * this class is will be called only once to initialize the DataSource
     static {
          try {
               Class.forName( "com.mysql.jdbc.Driver" );
               ds = getDataSource(     "com.mysql.jdbc.Driver",
                                        "root",
                                        "jdbc:mysql://localhost:3306/shop" );
               if (ds == null) {
                    String msg = "Connection Pool error";
                    logger.error(msg);
                    throw new GeneralException(msg);
               logger.info("DataSource has been initialized");
          } catch(Exception exception) {
               logger.error(exception.toString());
               try {
                    throw new GeneralException(exception.toString());
               } catch (GeneralException e) {
                    logger.error(e.toString());
     * get the connection from the pool (DataSource)
public void openConnection() throws GeneralException {
try {
     BasicDataSource bds = (BasicDataSource) ds;
     logger.info("NumActive: " + bds.getNumActive() + ", " + "NumIdle: " + bds.getNumIdle());
conn = ds.getConnection();
logger.info("Connection of " + database + " has been established");
} catch(Exception exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
* close the connection will actually return the connection to the pool (Must)
public void closeConnection() throws GeneralException {
     initResource();
try {
     if (conn != null){
               conn.close();
               logger.info("Connection of " + database + " has been closed");
} catch(SQLException exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
* prepare the calling stmt
public void prepareProcedure(String callStatement) throws GeneralException {
     initResource();
try {
     cs = conn.prepareCall(callStatement);
} catch(SQLException exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
* set the pass-in parameter for "String"
public void setParameter(int position, String parameter) throws GeneralException {
try {
     cs.setString(position, parameter);
} catch(Exception exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
* set the pass-in parameter for "Integer"
public void setParameter(int position, int parameter) throws GeneralException {
try {
     cs.setInt(position, parameter);
} catch(Exception exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
* execute the procedure and return the resultset
public ResultSet execProcedure() throws GeneralException {
try {
     rs = cs.executeQuery();
} catch(SQLException exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
return rs;
* close the statment and resultset
     private void initResource() throws GeneralException {
     try {
          if(rs != null) {
               rs.close();
          if(stmt!= null) {
               stmt.close();
          logger.info("Statement & Resultset have been free");
     } catch(Exception exception) {
     logger.error(exception.toString());
     throw new GeneralException(exception.toString());
Thanks mates!
myy

Thanks Saish,
Your response is really appreciated. Sorry about that
as i didnt know there is 'code' formatting button,
and I will look into the Singleton pattern.
As I'm still in the learning stage. Therefore, i
still have a lot of thing do not understand.
... use it in a method signature ...What is "a method signature" ?
A method signature is basically the method's parameters, return value, name and any access or other modifiers. The following is a method signature:
static final public void main(final String[] args)Between the braces of the method body is the implementation (or as I already alluded to, the method body).
Consider using an already-developed connection poolimplementation, such as Jakarta Commons DBCP ...
I'm trying to implement the Jakarta DBCP. Did I go
into the wrong way?
Sorry, did not read the imports. Yes, you are. However, I am confused about what you are trying to implement. You have a static method getDataSource(). You also have a static variable 'ds'. Use one or the other. I would be that there are seemingly random errors cropping up based on whether you remember to call getDataSource() or not.
You do not, generally, want the data source to be static. Multiple threads might use the class. And if there is only a static data source, you will either need to synchronize the methods that use the data source (resulting in a scaling bottleneck) or not synchronize them (which will totally destroy any concept of a logical unit of work or database transaction).
.. A static datasource, as in your class, can onlysafely be used by one thread at a time, potentially
introducing scaling bottlenecks (or race conditions)
in your system ...
So, you mean there is no need for the DataSource to
be static ?
No, in fact, IMO, it should not be. That is why you are pooling. Use instances. The pool will manage the connections and their availabilty for you.
Why are you throwing GeneralException everywhere?Here's a question: can someone using your class (a
caller) realistically be expected to handle a
database exception?
When there is a database error, I just want to stop
the process and redirect the user to an error page. I
will look into the unchecked exceptions. Thanks.
Unchecked exceptions do not need to be declared in a method signature or caught within the method body. Checked exceptions do. As such, an added benefit is that unchecked exceptions de-clutter your code.
In your initResources() method, what happens if theclose() on ResultSet throws an exception
Oh, yes. I'm so stupid.
Now I only have ...
     private static DataSource ds;     // set this to
be static so all threads share the same obj in JVM
     private Connection conn;
     private CallableStatement cs;
private void initResource() throws GeneralException
n {
     try {
          if(cs != null) {
               cs.close();
logger.info("CallableStatement has been
as been free");
     } catch(Exception exception) {
     logger.error(exception.toString());
throw new
throw new GeneralException(exception.toString());
You still have issues.
public void initResources() {
   if (rs != null) {
     try { rs.close(); } catch (SQLException ignore) { ignore.printStackTrace(); }
   if (stmt != null) {
     try { stmt.close(); } catch (SQLException ignore) { ignore.printStackTrace(); }
}Normally, this type of method would not be called initResources() but rather closeResources() or freeResources(). It would be called from within the 'finally' block of another method using the CallableStatement or ResultSet.
This is really is problem, would you mind to tell me
how to handle this(close the connection) if the
close() on either CallableStatement or Resultset
throws an exception ?
See above. Simply log the exception (there is usually nothing meaningful you can do if a close() fails, and it is up to you as a developer if this is an error or just a warning). Another option is to 'chain' exceptions. In your own exception, add a method 'addException(Throwable)'. This would add another exception to a List of exceptions. When you print the stack trace, iterate through the chained exceptions to print them all out. One place where I find this useful is rollback() code. If the original SQL statement fails AND the rollback fails, I definitely want to see that rollback() exception as well in my logs.
The DB thing makes me headache. What I actually
wanted is a solution for:
Let say I have a class "HelloAction.class" contains
the code:
public ActionForward XXX() {
     DbManager DB = new DBManager();
     ... do some DB thing here...
     SecondClass SC = new SecondClass();
     SC.doSomeOtherDbThing();
     ... do something else...
     ThirdClass TC = new ThirdClass();
     SC.doMoreOtherDbThing();
}There are some functions in SecondClass.class and
ThirdClass.class that will need database connection.
I consider 'global variable' is because I want these
two classes are able to use the same
connection(DbManager) from the function -
ActionForward XXX().
What is the best way to implement the above situation
(sharing the same connection in different classes &
sub-classes?
I also just realize that the problem of multi-threads
with these two class variables..
     private Connection conn;
     private CallableStatement cs;Really headache. I really appreciate any comments.
Thanks.
- myyPass the Connection or DataSource to each method or constructor. Call commit() or rollback() from the method that created the transaction.
- Saish

Jdev+ADF Mobile : Error java.lang.NullPointerException,need global variable

hi, i am using jdeveloper version 11.1.1.1.0.
i try to get value of field "id" from a table "customer" from input value from "username" and "password" form in welcome / login page.
the value of field "id" that logged on will be used for further operation like determine relationship with other table for showing data.
to accomplish that, i create a new java class "bean.java"
the content is simple, just a few variable like : eeid,eeuser,eepass, and more else.
each variable have accessors.
after create "bean.java", i register that class to faces-config.xml in managed beans tab. i give it description like below :
- name : beanku
- class : mvc.bean
- scope : session
to login, i check the login button with code like this :
public String cmdSigninee_action() throws ClassNotFoundException, SQLException {
String tuser = (String) inputUseree.getValue(); --> value of username
String tpass = (String) inputPassee.getValue(); --? value of password
bean ong = (bean) FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get("beanku"); --> it's ok here
ong.setSeeid("testing"); --> here is the error
i got an error message like shown below :
Target URL -- http://127.0.0.1:7101/madf-mvc-context-root/faces/welcome.jsp
Dec 4, 2009 11:39:26 PM oracle.jbo.uicli.mom.CpxUtils$Visitor logMainApplicationCpx
INFO: file:/C:/Documents and Settings/Ong/Application Data/JDeveloper/system11.1.1.1.33.54.07/o.j2ee/drs/madf/madf-mvc-webapp/WEB-INF/classes/mvc/DataBindings.cpx
Dec 4, 2009 11:39:27 PM oracle.adfinternal.controller.faces.lifecycle.JSFLifecycleImpl setLifecycleContextBuilder
INFO: ADFc: Initializing ADF Page Lifecycle for the JSF environment, LifecycleContextBuilder is 'oracle.adfinternal.controller.application.model.JSFDataBindingLifecycleContextBuilder'.
Dec 4, 2009 11:40:21 PM com.sun.faces.application.ActionListenerImpl processAction
SEVERE: java.lang.NullPointerException
javax.faces.el.EvaluationException: java.lang.NullPointerException
     at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:51)
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
     at org.apache.myfaces.trinidad.component.UIXCommand.broadcast(UIXCommand.java:190)
     at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:475)
     at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:756)
     at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
     at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
     at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
     at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
     at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
     at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
     at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.adf.model.servlet.ADFBindingFilter.doFilter(ADFBindingFilter.java:191)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:247)
     at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:157)
     at org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.security.jps.wls.JpsWlsFilter$1.run(JpsWlsFilter.java:96)
     at java.security.AccessController.doPrivileged(Native Method)
     at oracle.security.jps.util.JpsSubject.doAsPrivileged(JpsSubject.java:313)
     at oracle.security.jps.wls.util.JpsWlsUtil.runJaasMode(JpsWlsUtil.java:146)
     at oracle.security.jps.wls.JpsWlsFilter.doFilter(JpsWlsFilter.java:140)
     at oracle.security.jps.ee.http.JpsFilter.doFilter(JpsFilter.java:70)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.dms.wls.DMSServletFilter.doFilter(DMSServletFilter.java:202)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3588)
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
     at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
     at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2200)
     at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2106)
     at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1428)
     at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
     at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)
Caused by: java.lang.NullPointerException
     at mvc.backing.Welcome.cmdSigninee_action(Welcome.java:380)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at com.sun.el.parser.AstValue.invoke(AstValue.java:157)
     at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:283)
     at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:46)
     ... 38 more
Dec 4, 2009 11:40:21 PM com.sun.faces.lifecycle.InvokeApplicationPhase execute
WARNING: #{backing_welcome.cmdSigninee_action}: java.lang.NullPointerException
javax.faces.FacesException: #{backing_welcome.cmdSigninee_action}: java.lang.NullPointerException
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
     at org.apache.myfaces.trinidad.component.UIXCommand.broadcast(UIXCommand.java:190)
     at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:475)
     at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:756)
     at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
     at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
     at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
     at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)
     at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
     at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
     at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292)
     at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.adf.model.servlet.ADFBindingFilter.doFilter(ADFBindingFilter.java:191)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl._doFilterImpl(TrinidadFilterImpl.java:247)
     at org.apache.myfaces.trinidadinternal.webapp.TrinidadFilterImpl.doFilter(TrinidadFilterImpl.java:157)
     at org.apache.myfaces.trinidad.webapp.TrinidadFilter.doFilter(TrinidadFilter.java:92)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.security.jps.wls.JpsWlsFilter$1.run(JpsWlsFilter.java:96)
     at java.security.AccessController.doPrivileged(Native Method)
     at oracle.security.jps.util.JpsSubject.doAsPrivileged(JpsSubject.java:313)
     at oracle.security.jps.wls.util.JpsWlsUtil.runJaasMode(JpsWlsUtil.java:146)
     at oracle.security.jps.wls.JpsWlsFilter.doFilter(JpsWlsFilter.java:140)
     at oracle.security.jps.ee.http.JpsFilter.doFilter(JpsFilter.java:70)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at oracle.dms.wls.DMSServletFilter.doFilter(DMSServletFilter.java:202)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at weblogic.servlet.internal.RequestEventsFilter.doFilter(RequestEventsFilter.java:27)
     at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
     at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3588)
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
     at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
     at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2200)
     at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2106)
     at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1428)
     at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
     at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)
Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException
     at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:51)
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
     ... 37 more
Caused by: java.lang.NullPointerException
     at mvc.backing.Welcome.cmdSigninee_action(Welcome.java:380)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at com.sun.el.parser.AstValue.invoke(AstValue.java:157)
     at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:283)
     at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:46)
     ... 38 more
Dec 4, 2009 11:40:21 PM com.sun.faces.lifecycle.Phase doPhase
SEVERE: JSF1054: (Phase ID: INVOKE_APPLICATION 5, View ID: /welcome.jsp) Exception thrown during phase execution: javax.faces.event.PhaseEvent[source=com.sun.faces.lifecycle.LifecycleImpl@8aa35b]
<Dec 4, 2009 11:40:21 PM ICT> <Error> <HTTP> <BEA-101017> <[ServletContext@14855001[app:madf module:madf-mvc-context-root path:/madf-mvc-context-root spec-version:2.5], request: weblogic.servlet.internal.ServletRequestImpl@5a2f7[
POST /madf-mvc-context-root/faces/welcome.jsp?_adf.ctrl-state=4p5g40az1_4 HTTP/1.1
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*
Referer: http://127.0.0.1:7101/madf-mvc-context-root/faces/welcome.jsp;jsessionid=vs4JLZ7ppccm9mdq4z1RJn31c1Qj9ZpLmdHhT2BGTThzP7JnZfmJ!1909271282?_adf.ctrl-state=4p5g40az1_4
Accept-Language: en-us
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727)
Content-Length: 346
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: JSESSIONID=vs4JLZ7ppccm9mdq4z1RJn31c1Qj9ZpLmdHhT2BGTThzP7JnZfmJ!1909271282
]] Root cause of ServletException.
javax.faces.FacesException: #{backing_welcome.cmdSigninee_action}: java.lang.NullPointerException
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
     at org.apache.myfaces.trinidad.component.UIXCommand.broadcast(UIXCommand.java:190)
     at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:475)
     at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:756)
     at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
     Truncated. see log file for complete stacktrace
javax.faces.el.EvaluationException: java.lang.NullPointerException
     at org.apache.myfaces.trinidad.component.MethodExpressionMethodBinding.invoke(MethodExpressionMethodBinding.java:51)
     at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
     at org.apache.myfaces.trinidad.component.UIXCommand.broadcast(UIXCommand.java:190)
     at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:475)
     at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:756)
     Truncated. see log file for complete stacktrace
java.lang.NullPointerException
     at mvc.backing.Welcome.cmdSigninee_action(Welcome.java:380)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     Truncated. see log file for complete stacktrace
>
anyone can help me with those errors? i just need global variable, so i can use it for check relationship with other table.
or if anyone of you can give me another way to get the value of field "id" from a table?
thank you so much before! and i am sorry if my english is bad.

If you select the JSP page in the graphical stuts-config.xml overview in JDeveloper, you should see the properties of the JSP page in the property inspector. One of those properties defines the Java class that handles the action/forwarding/etc.
Then you should create a new Java-class that extends the original action handling class. Change the property in the graphical stuts-config.xml overview in JDeveloper to this new class.
Then add an event attribute to the submitbutton element in the form of your JSP page, e.g. seeDetails.
In your newly created class you can then create a new method: onSeeDetails. This method should be invoked when the submit button is pressed and the form is submitted.
In the ADF ToyStore demo there are some examples of Java classes that extend the standard action handler. There in the ViewController project.
ROnald

Where to store "global variable" for a web application

There are some "global" variables in my portal web application. e.g. email server
name, admin email address etc. Will web.xml context-param a good place to store these
kind of information?
If so, how do I retrieve it back from a java class? It is easy in a jsp file: appalication.getAttribute(),
but how about a pipeline component or input processor which are all java file.
Please help!
Thank you very much
Ellen

I still believe that the information like connectivity parameters to remote
servers in the distributed environments would be best stored in the JNDI
tree. I agree, that it is not a "general storage area", but I am not talking
about storing application run-time data either.
In the clustered environments it would provide additional benefits of
centralizing this kind information across the cluster.
Regards,
Mike
"Subrahmanyam Allamaraju" <[email protected]> wrote in message
news:[email protected]..
>
JNDI is not a general-purpose storage area, although you could bind data
in a JNDI tree. A better (and simpler) way is to store them as context
parameters. You could read the initial values for these variables from a
servlet init parameters.
Subbu
Michael Goldverg wrote:
Ellen,
I would advise to put you global variable in JNDI tree.
You can use jndi.properties file to store name-value pairs, which will
get
loaded into jndi tree at the server startup. Just put this file in your
application class path.
The other method would be to code a startup class to store the global
variable in the jndi tree.
Regards,
Mike
"ellen" <[email protected]> wrote in message
news:[email protected]..
There are some "global" variables in my portal web application. e.g.
email
>>
server
name, admin email address etc. Will web.xml context-param a good place
to
>>
store these
kind of information?
If so, how do I retrieve it back from a java class? It is easy in a jspfile: appalication.getAttribute(),
but how about a pipeline component or input processor which are all javafile.
Please help!
Thank you very much
Ellen

User Exit for Global Variables

Hello Gurus,
Which is the user exit where I can sed the code for the global variables
for eg:
0CYTLM - Cummulated to last month
If I want to write my own code, is it the same exit
thanks in advance

some docs may useful
http://help.sap.com/saphelp_nw04/helpdata/en/5c/8db0be555411d189660000e829fbbd/content.htm
http://help.sap.com/saphelp_nw04/helpdata/en/f1/0a56f5e09411d2acb90000e829fbfe/frameset.htm
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/a49bd590-0201-0010-51b9-ea4295036979
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/f1a7e790-0201-0010-0a8d-f08a4662562d
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/db37ce90-0201-0010-3c83-948c94792ae4

Use of global variables like g_cnt_transactions_transferred in the LSMW

Hi SapAll.
when i had a look at the some of the LSMW's whic use IDOC as the object of uploading data into SAP from external Files i have found in the coding under the step "Maintain Field Mapping and Conversion Rules" that they use some of the global variables like below
.if p_trfcpt = yes or sy-saprl >= '46A'.
EDI_DC40-DOCNUM = g_cnt_transactions_transferred + 1.
endif.
.EDI_DC40-CIMTYP = g_cimtyp.
.EDI_DC40-MESTYP = g_mestyp.
.EDI_DC40-MESCOD = g_mescod.
.if p_filept = yes.
EDI_DC40-SNDPOR = g_fileport.
elseif p_trfcpt = yes.
EDI_DC40-SNDPOR = g_trfcport.
endif.
my doubt is where i can find these variables 'g_cnt_transactions_transferred ','g_cimtyp','g_mescod','g_fileport','g_trfcport' in the LSMW and what is the use of the variable 'g_cnt_transactions_transferred ' in the LSMW.
I have treid to find out the above listed variables looking in step 'Maintain Field Mapping and Conversion Rules' under global variabels list and the other lists also but i couldnt found.
can any one help me in this ?
regards.
Seetha.

Hi Seetha,
In the LSMW Workbench go to the option user menu. And check the option display conversion program.
Now when you execute with the radio button on dislplay conversion program, you ll see the code that got generated in the background while you built your LSMW.
The global variables that you have mentioned are bound to be there in this program generated in the background..
You can put a break point here and see for yourself what the value of these global variables are at runtime.
File port, TRFC port , no. of transactions executed by one run of the LMSW Idoc program , message type are some of the fields that you have asked for .
Regards,
Arun

Java Threads vs. Native Global Variables

A brief description of the problem:
I am trying to integrate a multi-threaded Java app with legacy Fortran code. The Fortran code in question makes extensive use of global variables in the form of Fortran's Common Block data structure.
If multiple threads were allowed access to a native routine, they would over write each others data which is stored in global variables.
If only one thread at a time can have access to the native routine for the duration of the native routine, the whole advantage of using threads is completely nullified.
These native routines cannot be rewritten (3rd party code) and must be used.
One solution I envisioned was to load a new copy of the native shared object code for each Java object that used the native code. However, it seems System.loadLibrary() can only be used in a static context.
Is there any known solution to this problem?

Here is an elaboration on the earlier suggestions. It's a high overhead solution, because you have to start a bunch of JVMs.
1. You have a java control program, which will start up a pool of "services", make requests to them, and gather the results.
2. Each service is a small java program with a native method:
o java communications front-end.
o native method declaration.
o native - in your case fortran - method implementation.
3. Each service is started using "exec". That puts it in a separate process.
4, Since each service is a java program, you can use java to do communications between the control program and the service.
o You could use RMI.
o You could - perhaps - use java Process communications, i.e., have the services write to stdout, and have the control program capture the output.
o You could use socket communications.

Unit Testing and APEX Global Variables

We've recently started to unit test our database level PL/SQL business logic.
As such we have a need to be able to simulate or provide output from PL/SQL APEX components in order to facilitate testing of these components.
Some of the most obvious portions that need simulation are:
1. The existence of a session
2. The current application ID
3. The current page ID.
We currently handle requirement #1 by using apex_040100.wwv_flow_session.create_new
We handle 2 and 3 using the apex_application.g_flow_id and g_flow_step_id global variables.
I'm just wondering, how safe is it for us to use wwv_flow_session.create_new to simulate the creation of a session at testing time for those things which need a session?
I've also noticed that there are apex_application.get_application_id and apex_application.get_page_id functions whose output is not tied to the global variables (at least in our current version).
Is it safe for us to expect that we can set these global variables for use in testing or is apex moving to get_application_id and get_page_id functions away from global variables?
Will there be corresponding set_application_id and set_page_id functions in the future?
Sorry for the question bomb. Thanks for any help.

My first question would be why do you need to establish a session to test your PL/SQL?
wwv_flow_session is a package internal to APEX, and you should probably leave it be.
The get_application_id procedure you refer to is in apex_application_install, which is used for scripting installation of applications - not get/set of page ID like you're describing.
If you're uncomfortable using apex_application.g_flow_id, you can use v('APP_ID') or preferably pass the app_id/page_id as parameters to your procedures.
Your question seems to have a few unknowns, so that's the best I can describe.
Scott

Can F4IF_INT_TABLE_VALUE_REQUEST FM return a value in a global variable?

Hi everybody,
I need to use F4IF_INT_TABLE_VALUE_REQUEST FM because I have to let users select an specific option before choosing another value. The point is that I need to save in a program global variable what the user selects, and decide something with it in the program.
Is it possible that F4IF_INT_TABLE_VALUE_REQUEST FM returns the value in a sinple variable or it has to be paramter?
I look in a lot of previous threads but I didn't find anything, and I don't know if it's possible.
Thanks and kind regards,
MMP.

Hi,
Sure you can. All you need to do is to store what the function returns in your global variable. It don't need to be returned back to screen field.
DATA: BEGIN OF VALUES OCCURS 0,
         CARRID TYPE SPFLI-CARRID,
         CONNID TYPE SPFLI-CONNID,
       END OF VALUES.
DATA: VALUES_TAB TYPE TABLE OF VALUES,
          G_VALUE TYPE SPFLI-CONNID. "global variable to store what is returned
"in PAI first populate your table
SELECT CARRID CONNID
    FROM SPFLI
    INTO CORRESPONDING FIELDS OF TABLE VALUES_TAB
    UP TO 10 ROWS.
"then call the function but don't return the value to screen field
"If you specify the import parameters DYNPPROG, DYNPNR, and DYNPROFIELD, the useru2019s selection is
"returned to the corresponding field on the screen. If you specify the table parameter RETURN_TAB, the
"selection is returned into the table instead.
CALL FUNCTION 'F4IF_INT_TABLE_VALUE_REQUEST'
       EXPORTING
            RETFIELD         = 'CONNID'
            VALUE_ORG        = 'S'
       TABLES
            VALUE_TAB        = VALUES_TAB
            RETURN_TAB      = RETURN_TAB.
"now simply read first row of return tab and store the value returned there in some global var
READ RETURN_TAB INDEX 1.
MOVE RETURN_TAB-FIELDVAL TO G_VALUE.
Regards
Marcin

Problem with .DLL and global variables

Hi,
I need some helps to figure out my problem.
I wrote a .dll file to open and run a GUI. When I run it at the first time, it is ok. When I call it again, there is an error "Pointer to free memory passed to library. It will be ok if I completely exit the program that calls the .dll before re-call it. I think there is some problems with global variables when I call another thread. How can I free global variables between threads. Is there any solution for this problem?
Thanks

Vinh Pham:
Are you doing anything intentionally that frees your globals?
CVI ships with an example program that demonstrates calling a DLL to create a user interface: guidll.cws.
I made two simple modifications to guidll.cws.
1. In guidll.c, I made hpanel global by moving its declaration from RunDLLUI() to right below the #include statements.
2. In useguidll.c, I duplicated the lines calling RunDLLUI () and MessagePopup() to call the DLL gui twice.
I built the project and ran it. I had no problems with free'ed globals.
Take a look at the guidll example.
Can you either post your code or a modification to guidll that demonstrates the problem you're having?

Control global variable used in sub vi

Hi,
I've created a vi to read an instrument and to initiate its calibration with labview. This VI stores data in a global variable containing measurments and status of the instrument.
Now what I'm trying to do is create a sub vi with this to read&write 2 exactly identical instruments so I can finally create a VI that read all 3 instruments simultaneously.
How could I create a control on the global variable used by the sub VIs since it is the only thing that will change along with its COM port ?
I included a screetshot of the current VI.
Thanks,
Attachments:
Read_Calibrate.PNG ‏61 KB

I would make an array of values and then you just pass in which value to update. I would actually take it a step further and make an Action Engine that can update the data and return the data.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Loading a text file into a global variable issue - really a global var?

From all the documentation and examples I can find, it appears that it would be
correct to create a global array variable [outside of any functions] to load image names into,
then use these images for a slideshow. I want to make the app dynamic, in that changing the text file gives a new set of images.
The global variable goes null [no values] after the load event listener. Why is that?
Isn't global, well global, and alive for the duration of the SWF?
PARAMS.TXT:
monthNames=January,February,March,April,May,June,July,August,September,October,November,De cember&dayNames=Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
CODE:
var dNames:Array = new Array();
var mNames:Array = new Array();
var request:URLRequest = new URLRequest("images/params.txt");
var variables:URLLoader = new URLLoader();
variables.dataFormat = URLLoaderDataFormat.VARIABLES;
variables.addEventListener(Event.COMPLETE, completeHandler);
try
variables.load(request);
catch (error:Error)
trace("Unable to load URL: " + error);
trace("2 mNames 2: " + mNames[2]);
trace("2 dNames 3: " + dNames[3]);
stop();
function completeHandler(event:Event):void
var loader:URLLoader = URLLoader(event.target);
dNames = loader.data.dayNames.split(",");
mNames = loader.data.monthNames.split(",");
trace(loader.data.dayNames);
trace("1 mNames 2: " + mNames[2]);
trace("1 dNames 3: " + dNames[3]);
OUTPUT:
2 mNames 2: undefined
2 dNames 3: undefined
Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
1 mNames 2: March
1 dNames 3: Wednesday
How do I access these values after loading from the external file, after the load?
Thanks in advance.

The statement you quoted from whatever Adobe documentation is correct.
If you want to load the data into the arrays before anything else happens, then have anything else that happens execute via the completeHandler function... after the data is loaded and processed into the arrays.
the command: loadFile() executes before the trace("2:" +images[4]); command. The loadFile function is processed and the loading process BEGINS... but starting the loading does not delay the main processing from continuing down the line--the loading itself becomes a secondary/background task. The command was to execute the loadFile function and the processing of that function was completed. If you don't believe so, then add a trace...
function loadFile():void
     vars.dataFormat = URLLoaderDataFormat.VARIABLES;
     vars.addEventListener(Event.COMPLETE, onComplete, false, 0, true);
     vars.load(new URLRequest("images/fnames.txt"));
     trace("started loading");
If you add that trace, you should see that the loadFile function execution is completed and the next line in your code is then processed... trace(2....)
The addEventlistener does not stop anything. The addEventListener code is assigning a monitor, not a traffic controller... it is telling the monitor to indicate when the data has finished loading. It is not telling anything to stop program execution.
So if you want to wait until the data is loaded before you do anything else... it goes....
function onComplete(evt:Event):void
     var urlVars:URLVariables = evt.target.data;
     images = vars.data.images.split(",");
     tnails = vars.data.thumbnails.split(",");
     ................HERE.................

How do i create and pass a global variable from one vi to several sub-vi's?

Hi Guys,
I am trying to create a program that opens several front panels (sub-VI's) in sequence. in each front panel, the user would open a file that the name is obtained from the previous sub-VI. I would like to know how i could pass the filename and refnum of the file thorough from one sub-vi to another. A global variable would do it in VB, but how do we do global vars in LABWIEW. thanks
Papish

I put together a sample VI and Sub VI that illustrates how to pass a Refnum and access a data file while in a Sub VI.
For multiple VIs just repeat the sub VI process.
You probably don't wanna use a Global Variable if not needed (can add to the mess down the road haha).
Let me know if it helps you out! Or if I can clarify anything else!
Chances are if you have seen VI in the forest it hasn't fallen.
Attachments:
Passing Refnum.zip ‏21 KB

How do you override global variable values when calling oraxsl or xsl.exe?

I am a newbie to oracle xslt.
I have down loaded the latest version of xdk (10.1.0.2...). (Jan 2, 2009).
In the past I haveI used micorsoft's "msxsl.exe" to perform my transformations.
I am looking for a more up-to-date transformation tool.
I found Oracle's version, and thought I would try it out.
I have run the "bin/xsl.exe -hh" command.
I read its help data. It states that variables are
passed by coding a pramater "-V <var> <value>".
I have also examined the oraxls.bat file.
I found the documentation on "oracle.xml.parser.v2.oraxsl" class.
It states that parameters are passed after the "-p" switch.
It says the value of the -p parameter is "a list of paramemters".
I don't find this sufficient information to be useful.
I can spend days guessing, and I might get lucky.
I thought it my be better to ask for help.
I need to pass in (override) values for 3 global variables.
I saw the method
"setParam(namespace, variable, value)",
near the documentation for the "oraxsl" class.
How do you format the options string to communicate more than one param statement?
(in either xsl.exe and/or oraxsl class).
Suppose I have an xslt stylesheet as follows:
==================================================
<?xml version="1.0" ?>
<xsl:stylesheet version="1.1" xmlns:xsl='http://www.w3.org/1999/XSL/Transform' >
<xsl:param name='a' select='"default_a"' />
<xsl:param name='b' select='"default_b"' />
<xsl:param name='c' select="'default_c"' />
<xsl:template match='/'>
this is value for a: <xsl:value-of select='$a' />
this is value for b: <xsl:value-of select='$b' />
this is value for c: <xsl:value-of select=$c' />
<xsl:apply-templates />
</xsl:template>
</xsl:stylesheet>
========================================================
Now as part of the calling of the XSL processor I want to change the value of these
three global parameters.
I want:
a="current_a",
b="current_b",
and c="current_c"
How do I express this using xsl.exe and its paramter string (-V ????).
and/or how do I express it to the oraxsl class ( -p (xsl, a,"current_a"), (....) )???
The syntax for specifying this information is not very clear in either situation.
Of course I am making the "assumption" that by "param" they are
refering to "global parameters" (as in my stylesheet), rather than some other global parameters of XLST.
As an aside inquiry:
I had hopped that the Oracle's xsl Verion 2 routine could handle xslt 2.0 commands
such as "xsl:for-each-group", since it handled multiple xsl:outputs.
From reading some of the documentation it seems it only handles xslt 1.0 syntax/commands.
Is this true? (or is the documentation not up-to-date?).
Any help on passing param values to xsl.exe and/or "oraxsl" class is appreciated.
Thanks.

Here is the line from one of my testing .bat files that passed in one parameter. I can't recall if I've passed in two, but this will give you a starting point for passing in multiple
java -cp %CPath% oracle.xml.parser.v2.oraxsl -p show_image='yes' %ValXML% %ValXSLT% As for XSLT 2.0 support, it appears it does per {thread:id=503445}

How to Use Transient View Objects to Store Session-level Global Variables

hi
Please consider section "40.8.5 How to Use Transient View Objects to Store Session-level Global Variables"
at http://download.oracle.com/docs/cd/E14571_01/web.1111/b31974/bcstatemgmt.htm#ADFFD19610
Based on this documentation I created the example application
at http://www.consideringred.com/files/oracle/2010/ProgrammaticalViewObjectAndRollbackApp-v0.01.zip
It behaves as show in the screencast at http://screencast.com/t/qDvSQCgpvYdd
Its Application Module has a Transient View Object instance "MyEmployeesContextVOVI", as master for the child View Object instance "EmpInCtxJobVI".
On rollback the Transient View Object instance keeps its row and attribute values.
Also when passivation and activation is forced (using jbo.ampool.doampooling=false ) the Transient View Object instance seems to keep its row and attribute values.
questions:
- (q1) Why does the expression #{bindings.MyEmployeesContextVOVIIterator.dataControl.transactionDirty} evaluate as true when a Transient View Object instance attribute value is changed (as shown in screencast at http://screencast.com/t/qDvSQCgpvYdd )?
- (q2) What would be a robust approach to make a Transient View Object instance more self-contained, and manage itself to have only one single row (per instance) at all times (and as such removing the dependency on the Application Module prepareSession() as documented in "5. Create an empty row in the view object when a new user begins using the application module.")?
many thanks
Jan Vervecken

Thanks for your reply Frank.
q1) Does sample 90 help ? http://blogs.oracle.com/smuenchadf/examples/
Yes, the sample from Steve Muench does help, "90. Avoiding Dirtying the ADF Model Transaction When Transient Attributes are Set [10.1.3] "
at http://blogs.oracle.com/smuenchadf/examples/#90
It does point out a difference in marking transactions dirty by different layers of the framework, "... When any attribute's value is changed through an ADFM binding, the ADFM-layer transaction is marked as dirty. ...".
This can be illustrate with a small change in the example application
at http://www.consideringred.com/files/oracle/2010/ProgrammaticalViewObjectAndRollbackApp-v0.02.zip
It now shows the result of both these expressions on the page ...
#{bindings.MyEmployeesContextVOVIIterator.dataControl.transactionDirty}
#{bindings.MyEmployeesContextVOVIIterator.dataControl.dataProvider.transaction.dirty}... where one can be true and the other false respectively.
See also the screencast at http://screencast.com/t/k8vgNqdKgD
Similar to the sample from Steve Muench, another modification to the example application introduces MyCustomADFBCDataControl
at http://www.consideringred.com/files/oracle/2010/ProgrammaticalViewObjectAndRollbackApp-v0.03.zip
public class MyCustomADFBCDataControl
extends JUApplication
@Override
public void setTransactionModified()
    ApplicationModule vApplicationModule = (ApplicationModule)getDataProvider();
    Transaction vTransaction = vApplicationModule.getTransaction();
    if (vTransaction.isDirty())
      super.setTransactionModified();
}Resulting in what seems to be more consistent/expected transaction (dirty) information,
see also the screencast at http://screencast.com/t/756yCs1L1
Any feedback on why the ADF Model layer is so eager to mark a transaction dirty is always welcome.
Currently, question (q2) remains.
regards
Jan

Global variable in servlet

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