[users@httpd] Handler Chain (based on request method)

[Aaron Dalton <aa...@daltons.ca>]

I'm using mod_perl and CGI::Application::Dispatch to create a RESTful 
web application.  In the one resource, GETs should be sent to the 
default handler, and all other requests to the dispatcher.  I have tried 
using <Limit> and <LimitExcept>, but they do not appear to be working. 
The handlers get processed regardless.  Here is the current config:

	<Location /fs>
		<LimitExcept GET>
			Allow from All
			SetHandler perl-script
			PerlHandler BackCAD::Dispatch
		</LimitExcept>
		<Limit GET>
			Allow from All
			SetHandler default-handler
		</Limit>
	</Location>

Is there some way to make this work?  Do I need to write some sort of 
pre-dispatcher that checks the request method and returns DECLINED if 
it's GET?  But if it's *not* GET, how do I then pass control on to the 
other dispatcher?

Thank you so much for your time and assistance.
Aaron

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Re: [users@httpd] Handler Chain (based on request method)

[André Warnier <aw...@ice-sa.com>]

Aaron Dalton wrote:
> I'm using mod_perl and CGI::Application::Dispatch to create a RESTful 
> web application.  In the one resource, GETs should be sent to the 
> default handler, and all other requests to the dispatcher.  I have tried 
> using <Limit> and <LimitExcept>, but they do not appear to be working. 
> The handlers get processed regardless.  Here is the current config:
> 
>     <Location /fs>
>         <LimitExcept GET>
>             Allow from All
>             SetHandler perl-script
>             PerlHandler BackCAD::Dispatch
>         </LimitExcept>
>     </Location>
> 
> Is there some way to make this work?  Do I need to write some sort of 
> pre-dispatcher that checks the request method and returns DECLINED if 
> it's GET?  But if it's *not* GET, how do I then pass control on to the 
> other dispatcher?
> 
Interesting issue.
Several things come to mind, roughly :
1) you may want to (also) post this question on the mod_perl list 
(modperl@perl.apache.org)
2) what happens if you just remove the section
 >         <Limit GET>
 >             Allow from All
 >             SetHandler default-handler
 >         </Limit>
?
3) If nothing else works, you should be able to do this using mod_rewrite :
a) define a new <Location /fs-dispatch> with your perl module in it
b) use RewriteCond and RewriteRule to check for a "non-GET" call, and if 
so, re-direct (internally) to the /fsdispatch location
4) for your last question : I think that if your first handler returns 
DECLINED, Apache will automatically pass the request to the next defined 
handler in the chain.  The first handler returning "not-DECLINED" wins.
You could also create your "pre-dispatcher" as a PerlAccessHandler, 
which will always be executed in a previous phase (before content 
handlers).  That pre-dispatcher could just "push" the BackCAD::Dispatch 
handler as a content-handler only if needed, leaving the default Apache 
handler if it is a GET.
TIMTOWTDI, I think the saying goes.




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