NAME

Porting Modules from mod_perl 1.x to 2.x

Description

If you have released an Apache::Foo module on CPAN you may wonder what steps you should take to make your code working under 2.x while still preserving 1.x compatibility. This document attempts to answer some of the questions related to this issue.

Should the Module Name Be Changed?

While you can change the name of the module, it's the best to try to preserve the name and use some workarounds, if your module cannot be ported to run under 1.x and 2.x at the same time.

Most of the existing 1.x modules on CPAN should work with 2.x without any change. The ones that will not work are the .xs modules.

Let's say that you have a module Apache::Foo whose release version complient with mod_perl 1.x is 1.57. You keep this version on CPAN and release a new version 2.01 which is complient with 2.x and preserves the name of the module. It's possible that a user may need to have both versions of the module on the same machine. Since the two have the same name they obviously cannot live under the same tree. One attempt to solve that problem is to use MP_INST_APACHE2 Makefile.PL's option. If the module is configured as:

  % perl Makefile.PL MP_INST_APACHE2=1

it'll be installed relative to the Apache2/ directory. The second step is to change the documentation of your 2.x complient module to say:

  use Apache2 ();

in the code before the module is required or in startup.pl or

  PerlModule Apache2

in httpd.conf. This will @INC to look in the Apache2/ directory first.

The introduction of Apache2/ directory is similar to how Perl installs its modules in a version specific directory. For example:

  lib/5.7.1
  lib/5.7.2

Requiring a specific mod_perl version.

To require a module to run only under 2.x, simply add:

  use mod_perl 2.0;

to your module. You can also use the variable $mod_perl::VERSION.

Adjusting Modules to Work with 1.x and 2.x.

It's possible to adjust your module to work with both 2.x and 1.x. This is quite easy if your aren't using XS. Interfaces that are deprecated in 2.x can be enabled by adding:

  use Apache::compat();

in the code or startup.pl.

The variable $mod_perl::VERSION should be used in conditionals to use the appropriate code for 1.x or 2.x.

XS modules will need Makefile.PL/#ifdef logic to work with both versions. But the applications that use them should not need to know the difference.

META: example? probably the best to use some existing module that co-exists with the two versions.

Thread Safety

'make test' Suite

Apache::Test testing framework that comes together with mod_perl 2.x works with 1.x and 2.x mod_perl versions. Therefore you should consider porting your test suite to use the Apache::Test Framework.

Maintainers

Maintainer is the person(s) you should contact with updates, corrections and patches.

Stas Bekman <stas (at) stason.org>

Authors

• Stas Bekman <stas (at) stason.org>

• Doug MacEachern <dougm (at) covalent.net>

Only the major authors are listed above. For contributors see the Changes file.

cpanm mod_perl

perl -MCPAN -e shell
install mod_perl