$Id: README.apache2-mod_perl,v 1.1.2.4 2008-01-16 16:32:58 mike Exp $

We had some difficulty initially in getting the resolver to run under
Apache2/mod_perl2 -- it was initially developed under Apache the 1.3
series.  The results of our experiments are in the file
	web/conf/apache2.0/development.conf
which is a good starting point for making custom configurations.


=== FINDING THE RESOLVER LIBRARIES

For reasons we don't fully understand, mod_perl 2 (at least as
packaged for Debian) runs with taint-checking turned on, whereas
mod_perl 1 didn't.  Because of this, the PERL5LIB environment variable
is ignored, and so another approach is required to make the
development versions of the resolver Perl libraries available
(i.e. not whatever versions may have been installed from Debian
packages).  The best way seems to be to use the PerlSwitches
directive to pass in a "-I <dir>" option:
	PerlSwitches -I/usr/local/src/cvs/openurl-resolver/lib

In order for the PerlSwitches directive to be honoured, it's also
necessary to set "PerlOption +Parent", which means that a new and
dedicated Perl interpreter is created for each virtual host.


=== OBTAINING THE REQUEST OBJECT

At one point, it seemed as though in order to be able to obtain the
Apache request object using Apache2::RequestUtil->request(), we had to
set another Perl option in the Apache configuration:
	PerlOptions +GlobalRequest
As I write, this does _not_ seem to be necessary, but its worth noting
here as something to try if all does not go according to plan.


=== OBTAINING A USEFUL REQUEST OBJECT

The request object $r supplied by Apache2/mod_perl2 is not an
Apache2::Request, but an Apache2::RequestRec, which, astonishingly,
does not have the indispensible param() method.  To use param() you
need to create an Apache2::Request, which you can do using:
	$rr = new Apache2::Request($r);


=== DEFEATING THE UNDEFINED-SYMBOL DEMONS OF APREQ_HANDLE_APACHE

You may find that when you invoke one of various Apache2 functions --
such as creating an Apache2::Request object as suggested above -- you
run into this mysterious error message:
	/usr/sbin/apache2: symbol lookup error: /usr/lib/perl5/auto/APR/Request/Apache2/Apache2.so: undefined symbol: apreq_handle_apache2
You can do what I did and waste the best part of your life casting
wildly around for a fix, or you can just enable the "apreq" (Apache
Request?) module in Apache2:
	sudo a2enmod apreq
Well, of course!  How obvious!

(You may ask why, when mod_perl2 is enabled in the web server, the
ability to access a meaningful request object is not also enabled, or
at least why things are not arranged so that you get a comprehensible
and informative error-message if you try to use facilities that are
not enabled.  I certainly ask why.)


=== Stay tuned for more exciting adventures with Apache2.

