Re: Handler Chain (based on request method)

André Warnier <aw@xxxxxxxxxx> · Sat, 24 Oct 2009 14:45:57 +0200

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@xxxxxxxxxxxxxxx)

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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