send_http_header and subrequests

["Paul J. Lucas" <pj...@barefooters.org>]

	The second example on p. 128 of the Eagle book sets the content
	type and send the HTTP headers itself before running a
	subrequest.

	However, on p. 468, the documentation for the run() method says
	in part:

		When you invoke the subrequest's response handler in
		this way, it will do everything a response handler is
		supposed to, includinf sendinf the HTTP headers and the
		document body. ...  If you arevoking the subrequest
		urn() method from within your own content handler, you
		must not sen the HTTP headers and document body
		yourself ...

	These seem to contradict each other.  From testing, however, it
	seems as though the example on p. 128 is correct and the
	documentation on p. 468 isn't.  Is this true?

	The above aside, I'm having a problem when using subrequests
	when the subrequest also involves a (different) content handler.

	First, in a VirtualHost block, I have:

		AddType text/html	.chtml
		<Files *.chtml>
		  SetHandler		perl-script
		  PerlHandler		+Apache::HTML::ClassParser
		</Files>

	that sets up the aforementioned "different" content handler
	that uses .chtml files to generate dynamic content pages.  The
	ClassParser content handler, as expected, calls send_http_header()
	when it's ready to generate output.  It does, in part:

		sub handler {
			# ...
			return DECLINED if $r->content_type ne 'text/html';
			# ...
			$r->send_http_header();
			# ... generate content ...
			return OK;
		}

	Using this content handler by itself works just fine; however,
	when I try to use it in conjunction with another content
	handler, things don't work right.

	Briefly, I have a Location block like:

		<Location /get>
		  SetHandler		perl-script
		  PerlHandler		+My::Get
		</Location>

	that is a content handler that will, among other things, do
	on-the-fly conversions (similarly to the ImageMagick example in
	the Eagle book).  The My::Get handler does, in part:

		my $sub_r = $r->lookup_file( $full_path );
		my $status = $sub_r->status();
		unless ( $status == DOCUMENT_FOLLOWS ) {
			$r->log_error( "Can't look up $full_path" );
			return $status;
		}
		$r->send_http_header( $sub_r->content_type() );
		return OK if $r->header_only();
		return $sub_r->run();

	When I use My::Get by itself, it works fine: it will correctly
	serve documents of any type.  However, I'd like My::Get to
	simply be able to serve dynamic content pages if that's what
	it's asked to do to provide a uniform URL scheme.

	If $full_path refers to some .chtml file, things don't work
	right: I get two sets of response headers (200 OK) but the
	message that Apache prints is the canned "Document moved" error
	(with <A HREF="">here</A>, i.e., an empty URL).  Things I
	tried:

	1. In My::Get(), not calling send_http_header().  This results in
	   ordinary documents not being served correctly, e.g., the
	   content type is wrong.

	2. In My::Get(), if $full_path ends up being a .chtml file, do:

		$r->filename( $full_path );
		return DECLINED;

	   This results in the correct headers; however, the raw HTML is
	   served, i.e., the ClassParser handler is never called on the
	   file.

	I looked in the Eagle book about calling send_http_header()
	from within subrequests by reading the documentation for
	is_initial_req() and is_main(), but neither says anything about
	send_http_header().

	How can I get Apache to do what I want, i.e., have My::Get serve
	a file that is handled by another content handler?

	- Paul

Re: send_http_header and subrequests

[Doug MacEachern <do...@covalent.net>]

On Wed, 14 Jun 2000, Paul J. Lucas wrote:

> 	The second example on p. 128 of the Eagle book sets the content
> 	type and send the HTTP headers itself before running a
> 	subrequest.
> 
> 	However, on p. 468, the documentation for the run() method says
> 	in part:
> 
> 		When you invoke the subrequest's response handler in
> 		this way, it will do everything a response handler is
> 		supposed to, includinf sendinf the HTTP headers and the
> 		document body. ...  If you arevoking the subrequest
> 		urn() method from within your own content handler, you
> 		must not sen the HTTP headers and document body
> 		yourself ...
> 
> 	These seem to contradict each other.  From testing, however, it
> 	seems as though the example on p. 128 is correct and the
> 	documentation on p. 468 isn't.  Is this true?

right, subrequest->run does not output headers.
 
> 		my $sub_r = $r->lookup_file( $full_path );
> 		my $status = $sub_r->status();
> 		unless ( $status == DOCUMENT_FOLLOWS ) {
> 			$r->log_error( "Can't look up $full_path" );
> 			return $status;
> 		}
> 		$r->send_http_header( $sub_r->content_type() );

does it help if you change that to:

$sub_r->send_http_header;

?