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List:       apache-modules
Subject:    Re: [apache-modules] How input and output filter communicate
From:       Nick Kew <nick () webthing ! com>
Date:       2003-02-17 15:19:59
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On Mon, 17 Feb 2003, Kent Fitch wrote:

> But I'm very interested in request_config as a better
> alternative.  I can't find any good examples of it in
> the current Apache source - can you point me to some?

Not OTTOMH.  Quicker to cut&paste from my current work-in-progress at
http://access.www.webthing.com/software/mod_accessibility/

mod_accessibility is an output filter that rewrites outgoing HTML
to improve accessibility.  Apart from the filter itself, there's
a post_read_request hook that does some simple URL rewriting.
This serves to offer readers a choice of different views on a page,
and to preserve state.

So that's

typedef struct req_cfg {
  const char* view ;
  const char* variant ;  
} req_cfg ;

static int getView(request_rec* r) {

  ...

  req_cfg* cfg = apr_palloc(r->pool, sizeof(req_cfg)) ;

/* Parse /view=..../ component of URL and rewrite it out
  Store the results in cfg
*/

  ap_set_module_config(r->request_config, &accessibility_module, cfg) ;

  return DECLINED ; // keep out of the way of other modules
}

And then to access the stuff in the filter, I make that a field
in the filter context:

typedef struct saxctxt {
  ...
  req_cfg* view ;
  ...
} saxctxt ;

So in my filter_init function, I just use
  ctx->view =
	ap_get_module_config(f->r->request_config,&accessibility_module);

and my filter then has the data from the post_request hook in ctx->view,
and can now parse it to an enum, etc.


-- 
Nick Kew



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