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https://issues.apache.org/jira/browse/WICKET-3219?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Peter Ertl updated WICKET-3219:
-------------------------------

    Attachment: filter-extension.patch

> programmatical addition or removal of filters prior to wicket filter request 
> handling
> -------------------------------------------------------------------------------------
>
>                 Key: WICKET-3219
>                 URL: https://issues.apache.org/jira/browse/WICKET-3219
>             Project: Wicket
>          Issue Type: New Feature
>            Reporter: Peter Ertl
>            Assignee: Peter Ertl
>             Fix For: 1.5-M4
>
>         Attachments: filter-extension.patch
>
>
> [full-working patch included]
> I would like to extend WicketFilter so you can add (or remove) standard 
> servlet filters programatically to it. These will filter the request  prior 
> to wicket using Filter#doChain(). At the end of the filter chain wicket 
> itself will process the request.
> Usually the wicket request handling looks like this:
>  incoming browser request -> 
>    begin WicketFilter#doFilter ->
>      wicket request processing ->
>    end WicketFilter#doFilter ->
>  send response to browser
> Now when adding standard java.servlet.Filter instances to the WicketFilter 
> using something like
> --- sample code ---
> public class MyApplication extends WebApplication
> {
>       @Override
>       protected void init()
>       {
>               super.init();
>               XForwardFilter filter = new XForwardFilter(); // transparent 
> proxy handling behind front-end proxies
>               try
>               {
>                       getWicketFilter().addInterceptor(filter);
>                       ////////// getWicketFilter().addInterceptor(filter, 
> config); // alternate config (e.g. mock filter config since FilterConfig is 
> just an interface)
>               }
>               catch (ServletException e)
>               {
>                 // standard exception which can be thrown from 
> javax.servlet.Filter#init(FilterConfig)
>                       log.error(e.getMessage(), e);
>               }
> }
> --- EOF sample code ---
> the processing will change like that:
>   incoming browser request -> 
>     begin WicketFilter#doFilter ->
>       begin XForwardFilter#doFilter() ->
>         XForwardFilter processing ->
>         chain.doFilter(request,response) ->
>           invoke wicket request processing ->
>         end XForwardFilter#doFilter() ->
>     end WicketFilter#doFilter ->
>       send response to browser
> - The filter (= interceptor) will be invoked for the same filter path 
> WicketFilter is configured
> Being able to add filters like this will have the following advantages:
> - The filter can be added or removed anytime during the wicket application 
> lifecycle
> - You don't have to touch web.xml ever
> - You can specify mock filter configs or alternate filter configs using 
> (WicketFilter#addInterceptor(filter, alternateFilterConfig))
> - Tigher integration of the filter with wicket since the application and 
> session is already attached to the current thread context (similar to 
> WicketSessionFilter, but without web.xml fiddling)
> - Plugins can add filters without requiring any manual intervention by the 
> developer, this will make them more powerful
> - Filters can be removed thread-safe at runtime
> - Low-level request processing is really simple and requests or responses can 
> be wrapped using HttpServletRequestWrapper and HttpServletResponseWrapper
> - the filter class can not be invalid (<filter-class> in web.xml) since it's 
> checked by the compiler
> - Eventually migration from pre-wicket application might be easier
> Please check the patch to get the whole idea.
> Votes and comments are greatly appreciated :-)

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