"Shun, Vadim" wrote:
>
> Hi,
>
> I am storing some resources used on global level, such as database
> connection broker, in ServletContext.
> I am not sure however how to destroy them.
>
> The idea is that if this is the first time call, Controller Servlet init
> function initializes global resources and puts them in servlet context, so
> that all subsequent init functions reuse those resources. However I have a
> problem on how to destroying these global resources.
>
> Currently, my ActionServlet code has:
>
> public void destroy ()
> {
> // !!! actually should not do it here, should put in servlet
> context destroy
> DbConnectionBroker dbConnBroker = (DbConnectionBroker )
> getServletContext().getAttribute ("dbConnBroker");
> if ( dbConnBroker != null )
> dbConnBroker.destroy (); // destroy connection pool
> super.destroy();
> }
>
> Servlet initialization funciton has the following fragment of code:
> // !!!init DB pool, put it in servlet context
> DbConnectionBroker dbConnBroker = (DbConnectionBroker )
> getServletContext().getAttribute ("dbConnBroker");
> if ( dbConnBroker == null ) {
> // create one here
> dbConnBroker = new
> DbConnectionBroker(dbDriver,dbServer,dbLogin,dbPassword,
> minConns,maxConns,logFile, maxConnTime);
>
> getServletContext().setAttribute ("dbConnBroker",
> dbConnBroker);
> }
>
> The problem is that from looking at this code I can see that every time
> servlet is destroyed, it will unload global resources from servlet context,
> thus rendering the whole servletContext approach irrelevant (and dangerous I
> would say if there are other servlets reusing those resources). Of course,
> every servlet instance during init will have to recreate it again.
>
> I cannot avoid thinking of C++ where templates allowed smart reference
> counting of classes, thus I would be able to see if global resources are
> still in use (like auto_ptr STL template class and similar). However there
> must be some easier approach in Java for this particular problem (maybe some
> API call for servletcontext).
Context life-cycle support is one of the areas listed for analysis in
the specification work for JSP 1.2 (JSR 053). In JSP 1.0/1.1, the approach
you use (releasing context resources in the destroy() method of a servlet) is
the best way to do it.
Hans
--
Hans Bergsten [EMAIL PROTECTED]
Gefion Software http://www.gefionsoftware.com
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