Jan Luehe wrote:
Bill Barker wrote On 01/19/06 18:11,:
-----Original Message-----
From: Jan Luehe [mailto:[EMAIL PROTECTED]
Sent: Thursday, January 19, 2006 5:57 PM
To: tomcat-dev@jakarta.apache.org
Subject: Response not flushed before RD.forward() returns
Consider the following code snippet of a servlet's service() method:
public class DispatcherServlet extends HttpServlet {
public void service(HttpServletRequest req,
HttpServletResponse res)
throws IOException, ServletException {
request.getRequestDispatcher("/target").forward(request, response);
try {
Thread.currentThread().sleep(60000);
} catch (Exception ex) { }
}
where "target" prints some output to the response.
The code currently returns the output printed by "target" only after
DispatcherServlet's service() method has finished, instead of right
before RD.forward() returns.
This seems to be in violation of the Servlet Spec, which has this:
SRV.8.4 ("The Forward Method"):
Before the forward() method of the RequestDispatcher interface
returns, the response content must be sent and committed, and closed
by the servlet container.
The code at the end of o.a.c.core.ApplicationDispatcher.doForward()
looks like this:
// This is not a real close in order to support error
processing
if ( log.isDebugEnabled() )
log.debug(" Disabling the response for futher output");
if (response instanceof ResponseFacade) {
((ResponseFacade) response).finish();
} else {
// Servlet SRV.6.2.2. The Resquest/Response may have been
wrapped
// and may no longer be instance of RequestFacade
if (log.isDebugEnabled()){
log.debug( " The Response is vehiculed using
a wrapper: "
+ response.getClass().getName() );
}
// Close anyway
try {
PrintWriter writer = response.getWriter();
writer.close();
} catch (IllegalStateException e) {
try {
ServletOutputStream stream =
response.getOutputStream();
stream.close();
} catch (IllegalStateException f) {
;
} catch (IOException f) {
;
}
} catch (IOException e) {
;
}
}
In the above code sample, response will be an instance of
ResponseFacade, meaning it will be suspended instead of being flushed
and closed right away.
Does anyone remember why the "response instanceof ResponseFacade"
check is there? I would have expected the "else" case to always be
executed.
Without ever actually having looked at ResponseFacade, I'd always assumed
that ResponseFacade.finish called Response.finishResponse. And I would have
been wrong ;-). This would have done the commit/send/close properly.
I don't have time right now to dig through the SVN logs to see why it's this
way, but suspended doesn't really look good enough to satisfy the spec.
Yes. I'm afraid it's been like this forever.
And it has to stay like this forever too: this needs to get some post
processing done (like error pages, etc). If this person wants to flush,
let him call flush.
Rémy
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