Re: Denial Service Attack Prevention apache-tomcat modjk2

[Wade Chandler]

Shapira, Yoav wrote:
Hi,
You can use JavaScript to disable form elements, thereby graying them
out and preventing the user from clicking again.
Yoav Shapira
Millennium Research Informatics

-----Original Message-----
From: Steve [mailto:[EMAIL PROTECTED]
Sent: Thursday, June 10, 2004 10:52 AM
To: Tomcat Users List
Subject: Denial Service Attack Prevention apache-tomcat modjk2
Looking for a solution to prevent a user from click multiply times on a
function in which the application is still performing from the first
click.
The user thinkgs the app is not responding where in fact it is, then
causing the app to take a dump from multiply request.
Using cisco css LB into --> Apache, mod_jk2 into tomcat 4.1.29
any tips or pointers greatly appr
-s

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Replying on top of Yoav's because I don't have the other message.
If it is a large enough operation your could do something like this:
//check if running
String methodName = "com.mypackage.MyClass.myMethod";
//pull value from session test and add if needed.
Boolean isRunning = (Boolean)session.getAttribute(methodName);
if( isRunning != null && isRunning.booleanValue() )
{
   //hand off to other method that tells them to please wait.
}
else
{
//first let app know user is doing task.
session.setAttribute(methodName, new Boolean(true));
//perform that large task
try
{
//do work that might jump out here...
}
catch(Throwable e)
{
}
finally
{
   //ok, it's done...remove from session.
   session.removeAttribute(methodName);
}
}//end else
Now the large task can't eat up your cpu more than you let it because it 
only runs once per user at a time.  Sleeping the thread a little after 
so many iterations in loops also will help your entire server and 
application.  After maybe every 1000 iterations sleep for a couple of 
millis. Play with that sometimes it helps sometimes not.  It spreads out 
the load over time a bit and allows the computer to service more users, 
it just takes longer...

Hope that helps you some.
Wade
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