We've done this in eXo Platform : https://jira.exoplatform.org/browse/PLF-497

https://github.com/exoplatform/platform/commit/586e1b411c9a9509e3d415a9f0fcbb91bb76e1ba




        <external-component-plugins>
                <target-component>org.exoplatform.web.filter.ExtensibleFilter</target-component>



                <component-plugin>
                        <name>JSP filter Plugin</name>



                        <set-method>addFilterDefinitions</set-method>


                        <type>org.exoplatform.web.filter.FilterDefinitionPlugin</type>


                        <init-params>
                                <object-param>



                                        <name>JSP Filter</name>


                                        <object type="org.exoplatform.web.filter.FilterDefinition">



                                                <field name="filter"><object type="org.exoplatform.commons.platform.RedefinableResourceFilter"/></field>                                



                                                <field name="patterns">



                            <!-- WARNING: the mapping is expressed with regular expressions -->



                                                        <collection type="java.util.ArrayList" item-type="java.lang.String">



                                                                <value>


                                                                        <string>.*/.*\.jsp</string>


                                                                </value>
                                <value>



                                  <string>.*/favicon\.ico</string>


                                </value>                
                                                        </collection>



                                                </field>
                                        </object>



                                </object-param>
                        </init-params>



                </component-plugin>
        </external-component-plugins>


It's leveraging a customized filter called :  RedefinableResourceFilter that I'm not sure exists in Gatein (but should IMO) :




package org.exoplatform.web.filter;




import org.exoplatform.container.PortalContainer;




import java.io.IOException;




import javax.servlet.FilterChain;



import javax.servlet.ServletContext;


import javax.servlet.ServletException;
import javax.servlet.ServletRequest;



import javax.servlet.ServletResponse;


import javax.servlet.http.HttpServletRequest;




public class RedefinableResourceFilter implements Filter {




  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,



                                                                                           ServletException {



    HttpServletRequest req = (HttpServletRequest) request;



    PortalContainer pContainer = PortalContainer.getInstance(req.getSession().getServletContext());



    ServletContext context = pContainer.getPortalContext();



    String path = req.getRequestURI();



    String ctx = req.getContextPath();



    if (ctx != null && ctx.length() > 1 && path.startsWith(ctx)) {



      path = path.substring(ctx.length());



    }
    context.getRequestDispatcher(path).include(request, response);



  }

}




On Fri, Nov 29, 2013 at 3:23 PM, Juraci Paixão Kröhling <jpkroehling@redhat.com> wrote:
Nicolas,

My goal is to change the favicon from /portal, without affecting custom
modifications that might have been done at /sample-portal. I think we
have already this behavior for templates via extensions, but it doesn't
seem to work for other resources (like .ico files).

The final solution could be anything (extensions, service, ...), hence
the request for suggestions :-)

- Juca.

On 11/28/2013 05:07 PM, Nicolas Filotto wrote:
> I'm not sure I understand what you want to do, you want to be able to
> modify the favicon from an extension (like sample-extension) or from an
> new portal (like sample-portal)?
>
>
> On Thu, Nov 28, 2013 at 3:40 PM, Juraci Paixão Kröhling
> <jpkroehling@redhat.com <mailto:jpkroehling@redhat.com>> wrote:
>
>     All,
>
>     We have a request to display a specific favicon for JBoss Portal, and it
>     seems there's no "easy" (or correct) solution in place for that
>     right now.
>
>     The first intuitive solution would be to override the templates, to make
>     them link to the desired favicon. This doesn't scales, as the whole
>     template is duplicated and it will only cause headaches in the future.
>
>     The second possible solution would be to incorporate the path to the
>     favicon into the properties file, but this means having a fixed path to
>     the favicon, which is a step backwards from what there is today: in one
>     of the templates for /portal, it gets the favicon for the context path,
>     so, if the current portal is /example-portal, it currently gets the
>     favicon at /example-portal/favicon . With the favicon coming from the
>     properties file, this would not be the case anymore, as all favicons
>     would be coming from a fixed path.
>
>     The third solution would be to build a FaviconService, that would take
>     care of determining the proper favicon path. It sounds to me that this
>     is a bit of overkill, but would be a clean solution.
>
>     Of course, the best option would be to be possible to override the
>     favicon from /portal, but this doesn't seems to be possible at the
>     moment. It seems that only templates are overriden.
>
>     Before proceeding with the third solution (which seems the most
>     desirable as of now), I would like to get your comments, opinions and
>     suggestions on how this could be better handled.
>
>     Best Regards,
>     Juca.
>
>
>     _______________________________________________
>     gatein-dev mailing list
>     gatein-dev@lists.jboss.org <mailto:gatein-dev@lists.jboss.org>
>     https://lists.jboss.org/mailman/listinfo/gatein-dev
>
>
>
>
> _______________________________________________
> gatein-dev mailing list
> gatein-dev@lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/gatein-dev
>



_______________________________________________
gatein-dev mailing list
gatein-dev@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/gatein-dev



--
Patrice Lamarque
eXo - VP Products