This seems like a pretty clear-cut "bug" in the Servlet filter
architecture. The fact that one is unable to redirect a request once
response headers are commited (albeit not actually sent) is a silly
limitation.
I don't think commiting headers after Wicket operations is appropriate
either. There should be a safe way to commit headers within the Filter
before the Wicket operation, then if Wicket chooses to redirect, the
headers get discarded.
Anyway, it's too late for me to think straight (I've had a very long
day) but this is something we should look into in the future.
I don't know that IRedirectListener would work (before like you said,
it would allow setting of headers *after* processing, not before). The
only workaround I can think of is to store the headers ourselves in the
Wicket layer and only commit them to the Servlet API if a redirect does
not occur. In other words, emulate the desired behavior.
Gili
Johan Compagner wrote:
We could add something for that with pages like we do already for other
resources.
i also don't know what happens if you set headers afterwards instead of
at front (but that is depeding if it already send something to the
client i think)
Else you have to check the url. with a IRedirectListener param you can
set the headers
And bookmarkable pages also.
joahn
Gili wrote:
That seems to imply it is impossible to apply a servlet filter
which adds response headers (for caching). I mean, I have absolutely
no way of knowing ahead of time which Wicket page I am filtering is
going to redirect or not.
I believe Eelco originally recommended caching headers should be
set using servlet filters. If this is no longer viable, we'd have to
add support directly into Wicket core, no?
Gili
Johan Compagner wrote:
with a redirect nothing should be written to the stream i believe.
Gili wrote:
In my AddResponseHeaders filter (it's in the stack-trace) my
code reads:
HttpServletResponse response = (HttpServletResponse)
servletResponse;
// set the provided HTTP response parameters
for (Enumeration e=config.getInitParameterNames();
e.hasMoreElements();)
{
String headerName = (String) e.nextElement();
response.addHeader(headerName,
config.getInitParameter(headerName));
}
chain.doFilter(servletRequest, servletResponse);
so really all I am doing is setting response headers, why would
this cause problems for redirect? Is this normal?
Gili
Johan Compagner wrote:
that is strange somehow there is already written something to the
stream when we want to redirect
I added some more info (the redirect url) so that you can see which
urls are causing these problems.
johan
Gili wrote:
I just noticed this in my tomcat logs. Has anyone else
experienced the same thing? (This is rc3)
23:42:21,171 ERROR WebResponse:148 - Unable to redirect. HTTP
Response has already been committed.
23:42:21,171 ERROR [Webpage]:260 - Servlet.service() for servlet
Webpage threw exception
java.lang.IllegalStateException
at
org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:423)
at
wicket.protocol.http.WebResponse.redirect(WebResponse.java:156)
at
wicket.protocol.http.BufferedWebResponse.close(BufferedWebResponse.java:74)
at
wicket.protocol.http.WicketServlet.doGet(WicketServlet.java:226)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at
com.be.desktopbeautifier.web.filter.AddResponseHeaders.doFilter(AddResponseHeaders.java:44)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:526)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)
This does not occur on a regular basis but if it's a bug, it
would be nice to be able to track it down and fix it.
Gili
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