[CORE] move _ErrorPageWriter to myfaces-impl?

[Jakob Korherr <ja...@gmail.com>]

Hi,

I am currently working on MYFACES-2454 and I am stuck at the following
situation:

Spec section 6.2.3 explains the Default Error Page, which is generated in
MyFaces via the package private class javax.faces.webapp._ErrorPageWriter.
The spec says, if we have an <error-page> definition in web.xml that points
to a facelet page, this facelet page must be able to include the information
produced by (in case of MyFaces) _ErrorPageWriter via <ui:include
src="javax.faces.error.xhtml" />.

<ui:include> is handled by
org.apache.myfaces.view.facelets.tag.ui.IncludeHandler, thus it is part of
myfaces-impl and it cannot access _ErrorPageWriter.

So there a few ways to solve this problem:

1) Duplicate _ErrorPageWriter to myfaces-impl, which is just ugly

2) Move _ErrorPageWriter to myfaces-impl and make it public. This would also
allow custom error handlers (org.apache.myfaces.ERROR_HANDLER) to fall back
to the default behaviour (there was a request for that in the
myfaces-user-list recently).
However, we would not be able to invoke the ErrorPageWriter in
FacesServlet's service method any more. So we would have to invoke it either
from LifecycleImpl or from ResourceHandlerImpl, if the current request is a
resource request. Looking at the code in FacesServlet maybe makes things
clearer:

...
        try
        {

            ResourceHandler resourceHandler =
facesContext.getApplication().getResourceHandler();

            if (resourceHandler.isResourceRequest(facesContext))
            {
                resourceHandler.handleResourceRequest(facesContext);
            }
            else
            {
                _handleStandardRequest(facesContext);
            }
        }
        catch (Exception e)
        {
            handleLifecycleException(facesContext, e);
        }
...

This solution would also allow us to generate different error pages for
resource requests, because currently we always a text/html error page, also
if the request was for example image/jpg.


3) Invoke the _ErrorPageWriter in FacesServlet in either way, but if there
is an <error-page> in web.xml, save the output in a request-scoped variable,
which can be accessed by IncludeHandler, instead of writing it directly to
the request writer.


Input would be highly appreciated!!!!!

Regards,

Jakob Korherr