=head1 NAME

XAO::Web - XAO Web Developer, dynamic content building suite

=head1 DESCRIPTION

XAO::Web is a part of XAO open source web services suite. It allows to
build dynamic web content using data, templates and external input.

The distinguishing feature of XAO::Web is in its modular design where
almost every aspect of functionality can be altered and alterations can
be re-used. No complex code is embedded in the templates which allows
to upgrade code and templates separately or maintain multiple visual
representations of the same functionality at the same time.

Aside from that most interesting features of XAO::Web are:

=over

=item *

Perl code is not mixed with templates. Templates can be normal HTML
files if no processing is required.

=item *

A specific site can replace or modify standard XAO::Web objects if
required by overriding or extending their methods. You do not need to
re-implement entire object to make a site specific change.

In case of system object upgrade or bug fix there is no need to alter
site-specific changes normally.

=item *

Site can create any extension objects or embed third-party extensions
as well.

=item *

One server can serve arbitrary number of XAO::Web sites each
with however extended functionality without creating any conflicts. That
includes different modifications to the system objects for different
sites.

=item *

Not limited to Web environment, allows to build any dynamic
content -- content of mail messages or reports for instance.

=item *

Works with CGI or mod_perl (mod_perl is recommended for production
grade sites).

=item *

If used in mod_perl mode improves performance by using caching of
configuration, parsed templates, database handlers and so on.

=item *

XAO::Web is by default integrated with XAO::FS (see L<XAO::FS>) as a
database layer, but this is not a requrement -- if for any reason
a different database must be used for a site it can be easily and
gracefully achieved.

=item *

Hosting providers can allow their customers to build very complex sites
without allowing them to execute arbitrary code, by allowing to modify
only templates.

=back

=head1 INSTALLATION

Download tarball from a CPAN server near you, from the master site
(L<http://xao.com/>) or using links on L<http://freshmeat.net/> and then
install it in the usual way, just say:

  perl Makefile.PL
  make
  make test
  sudo make install

Saying "install XAO::Web" from the CPAN shell is a good way too:

  perl -MCPAN -eshell
  install XAO::Web

Using CPAN shell is usually the best way because all dependencies will
be resolved automatically. If you do manual installation then XAO::Web
depends on at least the following modules (look into Makefile.PL or
just watch closely the output of `perl Makefile.PL' for additional
dependencies):

  XAO::Base
  XAO::FS
  Digest::MD5
  Error
  MIME::Lite
  Test::Unit

When you run "perl Makefile.PL" you will be asked for XAO::Web test
database. That database is only used when you do `make test' and it have
to exist. It does not matter what is inside the database, it will be
completely wiped out for each test case. Normally the database should be
the same that you have used for XAO::FS tests and in case of MySQL is
usually 'test' or 'test_fs'.

The directory where templates get installed is the same that you
gave to XAO::Base when you installed it. Normally that directory is
/usr/local/xao -- we will assume that for the rest of the document.

=head1 FIRST-TIME RUNNING AND TESTING

You are almost there. Now is the time to try it!

Configure your Apache server so that it would execute
/usr/local/xao/handlers/xao-apache.pl when someone types URL like
http://test.company.com/cgi-bin/symphero.pl. Here is an example of a virtual
host configuration for that (or you can simply sym-link symphero.pl to
your existing cgi-bin directory if you have one):

 <VirtualHost 10.0.0.1:80>
  ServerName   test.company.com
  ScriptAlias  /cgi-bin/ /usr/local/xao/handlers/
 </VirtualHost>

After you configure and re-start your web-server point your browser at
http://test.company.com/cgi-bin/xao-apache.pl/mysite/ -- you should be
able to see the default page template processed by XAO::Web. If you do
not see it -- you might want to look into apache error log, usually
there is some additional information there.

In the URL you used to look at the default page includes 'mysite' as a
site name. In this case it can be anything you want, nothing depends on
the name because your site does not yet have any specific templates,
objects or configuration. We will get back to customizing your site
later.

Now let us look into the URL - it does not look good, does it? It
includes cgi-bin, site name and generally looks ugly, we agree. The way
to deal with it currently is to use mod_rewrite to hide that into Apache
configuration. We are working on the real mod_perl module that will
not require mod_rewrite, you should expect it with the next release of
XAO::Web.

Here is how to configure Apache with mod_rewrite in the meantime:

 <VirtualHost 10.0.0.1:80>
  ServerName   test.company.com
  ServerAlias  test.company.com
 
  <Directory /usr/local/xao/handlers>
   Options ExecCGI
   SetHandler cgi-script
  </Directory>

  RewriteEngine on
  RewriteRule   ^/images/(.*)$  \
                /usr/local/xao/projects/mysite/images/$1  \
                [L]
  RewriteRule   ^/(.*)$  \
                /usr/local/xao/handlers/xao-apache.pl/mysite/$1  \
                [L]
 </VirtualHost>

That leaves everything in /images/ to be processed by the web server
in the usual way and maps everything else to XAO::Web handler. Restart
Apache and try going to just http://test.company.com/ now -- you should
see the same default page as before.

And finally, here is an example of mod_perl configuration, you should
use it for production grade sites. The only difference is in <Directory>
block.

 <VirtualHost 10.0.0.1:80>
  ServerName   test.company.com
  ServerAlias  test.company.com
 
  <Directory /usr/local/xao/handlers>
   Options ExecCGI
   SetHandler perl-script
   PerlHandler Apache::Registry
   PerlSendHeader Off
  </Directory>

  RewriteEngine on
  RewriteRule   ^/images/(.*)$  \
                /usr/local/xao/projects/mysite/images/$1  \
                [L]
  RewriteRule   ^/(.*)$  \
                /usr/local/xao/handlers/xao-apache.pl/mysite/$1  \
                [L]
 </VirtualHost>

That is it, if you got so far your installation of XAO::Web works fine
and you can move on to actually building a custom web site.
 
=head1 SITE DEVELOPMENT

Before you go any further it is recommended that you keep cgi-bin
configuration sample from the examples above as opposed to
mod_perl. Mod_perl development has its own peculiarities related
to caching of modules and content and you can get back to that
later. Cgi-bin based configurations are usually much easier to develop
and debug.

Here is a couple of steps to start the development of a new site.

=over

=item 1

Choose a name for your site. It have to start with a B<lowercase letter> and
may contain letters, digits and underscore signs. Let's assume you've
chosen "mysite" as a name.

=item 2

Create a sub-directory in /usr/local/xao/projects with the name of
your site (/usr/local/xao/projects/mysite in our case). This
directory is the home directory of your site. Everything else below is
relative to that directory. For simplicity you might want to sym-link
that directory into your home directory.

=item 3

Create a sub-directory named 'objects'. Place a configuration file
called 'Config.pm' inside of it. There is a couple of requrements for
that file:

=over

=item *

Package name have to be 'XAO::DO::Config'.

=item *

Usually it defines an init() method that will initialize site
configuration. In mod_perl environment that method will be called
only once when the site is initialized for the first time. That means
that init() is a good place to open connection to a database and it
is recommended to do that as most of XAO modules require database
connection to work properly.

=back

Here is an example of configuration module Config.pm for "mysite" site:

 # Configuration for mysite
 #
 package XAO::DO::Config;
 use strict;
 use XAO::Objects;

 # Inheritance from the system Config object
 #
 use base XAO::Objects->load(objname => 'Config', baseobj => 1);

 # Site configuration values. A lot of stuff can be stored here for
 # different modules, base_url is not required, but recommended.
 #
 my %data=(
     base_url        => "http://test.company.com",
     base_url_secure => "http://test.company.com",
 );

 ##
 # Initializing configuration object for our site
 #
 sub init {
     my $self=shift;

     # Creating a database configuration object and embedding it into our
     # configuration, see below for explanation
     #
     my $fsconfig = XAO::Objects->new(
            objname  => 'FS::Config',
            odb_args => {
                dsn       => 'OS:MySQL_DBI:test_fs',
                user      => 'test',
                password  => 'test',
            }
        );
     $self->embed(fs => $fsconfig);

     # Storing configuration into embedded hash
     #
     $self->embedded('hash')->fill(\%data);

     # And finally calling base class' init() method
     #
     $self->SUPER::init();
 }

 1;

For the more detailed description of `embedding' and initialization
process in general please refer to L<XAO::DO::Config>.

=item 4

At that point you should already be able to see
your new site in your browser. Just point it to
http://test.company.com/cgi-bin/xao-apache.pl/mysite/ or just
http://test.company.com/ depending on your Apache configuration.

But in order to do something useful you normally need to create one more
directory - 'templates'. That directory will contain all templates of
your site and unless you use some extended features of XAO::Web the
layout of files in this directory directly translates into URIs.

Nothing else is used by XAO::Web and usually you would also create
directories like 'images' or 'static'; put your site to CVS version
control or make some kind of installation tools for it. It is all up to
you.

=back

This is it. Try placing an index.html file into your 'templates'
directory and go to browser to check how it appears.

=head1 AUTHORS

Copyright (c) 2000-2001 XAO Inc.

XAO::Web was created and is maintained by Andrew Maltsev
<am@xao.com>. Creating of XAO::Web would not be possible without
valuable comments and ideas from everybody on our team and especially
from Marcos Alves, Bil Drury, Brian Despain and Jason Shupe.

=head1 SEE ALSO

Recommended reading:
L<XAO::Web>,
L<XAO::Objects>,
L<XAO::DO::Config>,
L<XAO::FS>,
L<XAO::DO::FS::Config>.

=cut
