Re: Number of users logged

On Thu, 2 Mar 2000, Wes Biggs wrote:

> If you want the number of concurrent requests to a particular servlet, I
> would suggest you declare it as an application-scope variable.  At the
> beginning of your service method, increment a counter, at the end,
> decrement it:
> 
> ServletContext application = getServletContext();
> Integer count = null;
> synchronized (application) {
>   count = (Integer) application.getAttribute("countMyServlet");
>   if (count == null) count = new Integer(1);
>   else count = new Integer(count.intValue() + 1);
>   application.setAttribute("countMyServlet", count);
> }
>  // bulk of service()/doGet()/doPost() here
> synchronized (application) {
>   count = new Integer(count.intValue() - 1);
>   application.setAttribute("countMyServlet", count);
> }
> 
> I would put the decrement operation in a finally {} clause to be safe.

Of course, you have to set the lifetime (Servlet Timeout) of the servlet
to -1 to avoid the reset of the servlet!

Another way would be to add a CounterFilter to the frame of the servlet,
but it is related to Jigsaw, so you have to find a way to pass it to the
servlet, by extending CounterFilter.

      /\          - Yves Lafon - World Wide Web Consortium - 
  /\ /  \        Architecture Domain - Jigsaw Activity Leader
 /  \    \/\    
/    \   /  \   http://www.w3.org/People/Lafon - ylafon@w3.org