Re: TC4's classloader choking on xerces.jar (maybe)
- Original Message - From: "Craig R. McClanahan" [EMAIL PROTECTED] Tomcat 4 follows the new rules in the servlet 2.3 PFD spec, which allows a container to change this so that loading starts with your WEB-INF areas first. Consider the following scenario - I put a copy of the Postgres JDBC driver (just to show that it's not specific to xml parsers :-) in my shared library directory, because lots of my apps need it. But, one of my webapps needs a different version of the Postgres driver, because it depends on a new feature that was implemented in a later version. So, I put the new driver file in the WEB-INF/lib directory of my webapp, and install it in Tomcat. Under Tomcat 3.2, the newer driver is ignored (because it's got the same class names). Under Tomcat 4.0, the newer driver is respected for that webap -- all others continue to use the shared one. Craig, I have a small doubt here. If I place the same jar file containing the class xyz.class in the tomcat/lib directory and in WEB-INF/lib directory, then will tomcat load the class from the tomcat/lib directory or WEB-INF/lib directory? If it is loaded from the WEB-INF/lib directory then this class gets loaded by a different classloader(webapp class loader) and is incompatible with the classes loaded from tomcat/lib. Should the container not check the META-INF/MANIFEST.MF to find out if the versions are same and if the versions are same it loads the class from tomcat/lib directory. Or do the specs mandate that any class in the WEB-INF/lib directory overrides class found in the tomcat/lib directory. Do the classes in WEB-INF/lib override the classes on the classpath in tomcat 4.0? Regds, Gokul Craig McClanahan - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
Re: NullPointerException from HttpSessionFacade.invalidate()
Hans Bergsten wrote: [...] The spec may not be explicit enough about this, but the session object you get back from the getSession() object is a container-managed object that the application is not supposed/allowed to keep long-lived references to. It's the same as with all other container-objects made available to the application; request, response, JSP tag handlers, etc. I'm not sure why you're keeping references to the session objects in you're application, but if you describe what you're trying to do I'm sure I can give you a hint about another way to accomplish the same thing without the problems you have with your current solution. I amtrying to disallow a single user to have multiple login sessions valid at any given time. I have to enforce this even if the user tried to login from two different machines. Can you suggest a solution for this which works on tomcat 3.2.1 and uses servlet specs 2.2 only. Regds, Gokul
Re: NullPointerException from HttpSessionFacade.invalidate()
- Original Message - From: "Hans Bergsten" [EMAIL PROTECTED] Gokul Singh wrote: Hans Bergsten wrote: [...] I am trying to disallow a single user to have multiple login sessions valid at any given time. I have to enforce this even if the user tried to login from two different machines. A small addition here. The requirement is that the user be allowed to login by creating a new session on login request and invalidating any valid session that he may have at that time. To be more elaborate. 1. A user U logs in and has a session associated with him i.e. S1. 2. user U goes to another machine and tries to login. 3. The user U should get a new session S2 with S1 being invalidated. I hope the requirements are now clear. archives for details). The bottom line is that a session is associated with a "client", not a "user". Agreed. Can you suggest a solution for this which works on tomcat 3.2.1 and uses servlet specs 2.2 only. Something like this should work in any compliant container. Thanks for putting down the whole code for me. I already implement this philosophy in my code. But the requirements are slightly different as spelled above. To make sure a user only logs in once, check if the loginID is already in the context structure before allowing a new login and creating the UserBean. The requirement is that the user can login any no. of times he wants. But he should have only one valid session and that should be the session from the last successful login attempt as mentioned above. Can you please tell me if this is possible using 2.2 specs and tomcat 3.2.1 Regds, Gokul PS: I have joined this list today only. I am not sure if this posting is appropriate for this list or not. If it is inappropriate here, then please mail to me privately. Hans -- - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
NullPointerException from HttpSessionFacade.invalidate()
Hi,I am trying to build a login servlet and get a
NullPointerException from HttpSessionFacade class in Tomcat 3.2.1.The code
of the simple version of the servlet which reproduces theproblem is attached
at the end of this mail along with the stack trace of the Exception
thrown.This piece of code works fine on tomcat 3.1.1 but fails on tomcat
3.2.1
To reproduce the error,1. start tomcat 3.2.1 afresh.2. Login from a
browser.The password field is not required as for now.3. Open another
browser (not a new instance of the same browser) on the samemachine or
another machine.4. Login with the same username.the servlet does the
following1.it invalidates any existing session on this request.2.it
checks the context to find if the present user has any associatedsession and
if it is there tries to invalidate it. (This is where I get theexception,
given below).3. creates a new session.4. puts the new session into the
context with the user id.In tomcat 3.2 is the session object which I get
( actually HttpSessionFacade) valid only for the request or can span multiple
Requests?
Any help would be greatly appreciated.
I am not on this mailing list. Please send a CC to me at [EMAIL PROTECTED] when replying to
this mailRegds,Gokul= 8 SERVLET CODE
= 8 ===import javax.servlet.*;import
javax.servlet.http.*;import java.io.*;public class
TestSessionBehaviourextends HttpServlet{private static String
STR="LOGIN.SESSION.USER.";public void doGet(HttpServletRequest req,
HttpServletResponse res)throws IOException,
ServletException{ res.setContentType("text/html");
PrintWriter out = res.getWriter(); sendLoginPage(out);
out.close();}public void doPost(HttpServletRequest req,
HttpServletResponse res)throws IOException{ String
name = req.getParameter("id"); HttpSession objSession =
req.getSession(false); // if the present request has a session
invalidate it. if(objSession != null)
objSession.invalidate(); // if this user has a valid session,
invalidate it. objSession =
(HttpSession)getServletContext().getAttribute(STR+name); if
(objSession != null) { System.out.println("The session
from context retrieved"); try
{ objSession.invalidate();
}catch(IllegalStateException ex) { }
} // create new session objSession =
req.getSession(true); // store in the context the username and
session.
getServletContext().setAttribute(STR+name,objSession); // send
reciept html res.setContentType("text/html"); PrintWriter
out = res.getWriter(); sendReceipt(out);
out.close();}private void sendReceipt(PrintWriter
out){
out.println("htmltitleReceipt/titlebodyThe login
isrecorded/body/html");}private
void sendLoginPage(PrintWriter out){
out.println("htmltitleTest Login/titlebodyPlease
login brformmethod=post tabletr");
out.println("tdName /tdtdinput type=text name=id
/td/tr");
out.println("trtdPassword/tdtdinput
type=textname=pass/td/tr");
out.println("trtdinput type=reset
value=reset/tdtdinputtype=submit
value=login/td/table");
out.println("/form/body/html");}}=
8= EXCEPTION THROWN 8 =Internal Servlet
Error:java.lang.NullPointerExceptionatorg.apache.tomcat.facade.HttpSessionFacade.invalidate(HttpSessionFacade.java:136)at
TestSessionBehaviour.doPost(TestSessionBehaviour.java:33)at
javax.servlet.http.HttpServlet.service(HttpServlet.java:760)at
javax.servlet.http.HttpServlet.service(HttpServlet.java:853)at
org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:404)at
org.apache.tomcat.core.Handler.service(Handler.java:286)at
org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)atorg.apache.tomcat.core.ContextManager.internalService(ContextManager.java:797)at
org.apache.tomcat.core.ContextManager.service(ContextManager.java:743)atorg.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:210)atorg.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)atorg.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:498)at
java.lang.Thread.run(Thread.java:484)= 8= 8
=
---"The
proverb warns that, 'You should not bite the hand that
feedsyou.' But maybe you should, if it prevents you from feeding
yourself."--Thomas
Szasz---
