Re: [Webwork-devel] Action load error handling in ServletDispatcher...

[Matt B. <ma...@sm...>]

see comments below

----- Original Message -----
From: "Joel Peach" <jp...@tr...>
To: <web...@li...>
Sent: Tuesday, May 07, 2002 9:38 AM
Subject: [Webwork-devel] Action load error handling in ServletDispatcher...


> Developers,
>
> I'm in the process of creating a custom action factory proxy to handle
authentication and authorization requirements in our system that can't be
serviced by container-managed auth. I've noticed a potential issue in the
way ServletDispatcher handles errors from the ActionFactoryProxy chain when
loading the action and wanted to bring it to your attention as I create a
patch.
>

The problem with the patch is the scenario where you may be trying to go to
the action which failed to be created. For instance ERROR might map to the
action that threw the exception. The way it is now, you can map back to the
same action and everything is fine.

> I've looked through the commit logs and the archives of this list and
haven't been able to find much in the way of how errors are to be addressed
in the ActionFactoryProxy chain. Looking at ServletDispatcher, it seems when
ActionFactory.getAction() is called, all Exceptions are trapped and a 404
error is sent back to the browser via the servlet response.
>
> However, in ParametersActionFactoryProxy, a patch was committed (revision
1.7) to trap IllegalArgumentException while setting the action properties
and propogate them to the ServletDispatcher as a ResultException. The
comment to the commit and in the source file for
ParametersActionFactoryProxy indicate that  the ResultException is to result
in the error view getting displayed for the action. Unfortunately, with the
way ServletDispatcher is handling exceptions at this point, the expected
behavior will never occur.

Hmm. It works. I checked in the FormTest where it throws
IllegalArgumentException instead of using doValidate(). Take a look at it.

>
> I'm wondering if I'm missing some subtlety of exception handling for the
action factory proxy chain or if the ServletDispatcher is in need of a way
to flexibly handle errors that occur as the Action is being instantiated?
>
> As I've been working on this patch, I've encountered some difficulty
resulting from the structure of ServletDispatcher's service() method and
that the action variable in that method is declared final. As far as I can
tell the declaration of the action variable as final is to prevent code
further down in the method from overwriting the variable after it has been
loaded. Can anyone please shed light on this?
>
> Help much appreciated and I look forward to being able to help out,
>
> -Joel
>
>
>
>
> ===================
> Joel Peach
> Tracerdigital, LLC
> 7632 Choctaw Place
> Columbus, OH
> United States
> p: (614) 540-3055
> e: jp...@tr...
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