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

Re: Handler Chain (based on request method)

[André Warnier <aw...@ice-sa.com>]

André Warnier wrote:
>>
> Just by curiosity, what happened to the suggestions I gave you on the 
> Apache httpd list (apart from the first one, which was to cross-post 
> here) ?
> 
Ok, sorry, I see that response to the httpd list just got there.
Maybe better to move the whole discussion here, there is probably more 
focused help available.

Re: 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>
>         <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?
> 
Just by curiosity, what happened to the suggestions I gave you on the 
Apache httpd list (apart from the first one, which was to cross-post here) ?

Also, the reason why the above does not work is probably that the 
<Limit...> sections are not really full containers.  So your SetHandlers 
above probably overwrite one another regardless, and only the last one 
counts.

Another quick/cheap hack maybe :

 >     <Location /fs>
 >             Allow from All
 >             SetHandler perl-script
 >             PerlHandler BackCAD::Dispatch
 >     </Location>

then modify the code of BackCAD::Dispatch to return DECLINED if it's a GET.
Honestly, I've never tried that, and I don't know if then Apache would 
process it with its default handler.  But it's worth a try maybe.

Re: Handler Chain (based on request method)

[Perrin Harkins <ph...@gmail.com>]

On Wed, Oct 28, 2009 at 12:58 PM, Aaron Dalton <aa...@daltons.ca> 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.

Those are for rejecting requests, not mapping them to handlers.  I
would either use mod_rewrite to map the GET requests to a different
location, or make a PerlTransHandler to deal with it.

> Do I need to write some sort of
> pre-dispatcher that checks the request method and returns DECLINED if
> it's GET?

Right, that would be the TransHandler approach.

> But if it's *not* GET, how do I then pass control on to the
> other dispatcher?

You can set the handler for the current request from within the
script.  Take a look at the docs for examples.  I know you'll find
some if you search for "default-handler" in the mail archives too.

- Perrin