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[catagits/Catalyst-Manual.git] / lib / Catalyst / Manual / Tutorial / 01_Intro.pod

=head1 NAME

Catalyst::Manual::Tutorial::01_Intro - Catalyst Tutorial - Chapter 1: Introduction


=head1 OVERVIEW

This is B<Chapter 1 of 10> for the Catalyst tutorial.

L<Tutorial Overview|Catalyst::Manual::Tutorial>

=over 4

=item 1

B<01_Introduction>

=item 2

L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics>

=item 3

L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics>

=item 4

L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>

=item 5

L<Authentication|Catalyst::Manual::Tutorial::05_Authentication>

=item 6

L<Authorization|Catalyst::Manual::Tutorial::06_Authorization>

=item 7

L<Debugging|Catalyst::Manual::Tutorial::07_Debugging>

=item 8

L<Testing|Catalyst::Manual::Tutorial::08_Testing>

=item 9

L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD>

=item 10

L<Appendices|Catalyst::Manual::Tutorial::10_Appendices>

=back


=head1 DESCRIPTION

This tutorial provides a multi-part introduction to the Catalyst web
framework. It seeks to provide a rapid overview of many of its most
commonly used features. The focus is on the real-world best practices
required in the construction of nearly all Catalyst applications.

Although the primary target of the tutorial is users new to the Catalyst
framework, experienced users may wish to review specific sections (for
example, how to use DBIC for their model classes, how to add
authentication and authorization to an existing application, and/or
form management).

You can obtain the code for all the tutorial examples from the
catalyst subversion repository by issuing the command:

    svn co http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/Tutorial/ CatalystTutorial

This will download the most recent code for each chapter of the
tutorial into the CatalystTutorial directory on your machine.

B<These reference implementations are provided so that when you follow
the tutorial, you can use the code from the subversion repository to
ensure that your system is set up correctly, and that you have not
inadvertently made any typographic errors, or accidentally skipped
part of the tutorial.>

B<NOTE: You can use any Perl-supported OS and environment to run
Catalyst.> It should make little or no difference to Catalyst's
operation, B<but this tutorial has been written using the Debian 6 Live
CD> because that represents a quick and easy way for most people to try
out Catalyst with virtually zero setup time and hassles.  Also, the
tutorial has been tested to work correctly with the versions of Catalyst
and all the supporting modules in Debian 6 (see "VERSIONS AND
CONVENTIONS USED IN THIS TUTORIAL" below for the specific versions for
some of the key modules), so B<if you think you might be running into an
issue related to versions> (for example, a module changed its behavior
in a newer version or a bug was introduced), B<it might be worth giving
Debian 6 a try>.

If you plan to follow along with Debian 6, you can jump down to the
"Debian" section under L</"CATALYST INSTALLATION"> below and it will
walk you though the setup of a fully functional Catalyst environment. If
you would prefer to install directly from CPAN, you can download the
example program and all the necessary dependencies to your local machine
by installing the C<Task::Catalyst::Tutorial> distribution:

     cpan Task::Catalyst::Tutorial

This will also test to make sure the dependencies are working.  If you
have trouble installing these, please ask for help on the #catalyst
IRC channel, or the Catalyst mailing list.

Subjects covered by the tutorial include:

=over 4

=item * 

A simple application that lists and adds books.

=item *

The use of L<DBIx::Class|DBIx::Class> (DBIC) for the model (including
some of the more advanced techniques you will probably want to use in
your applications).

=item * 

How to write CRUD (Create, Read, Update, and Delete) operations in
Catalyst.

=item *

Authentication ("auth").

=item * 

Role-based authorization ("authz").

=item * 

Attempts to provide an example showing current (5.9) Catalyst
practices.

=item * 

The use of Template Toolkit (TT).

=item * 

Useful techniques for troubleshooting and debugging Catalyst
applications.

=item * 

The use of SQLite as a database (with code also provided for MySQL and
PostgreSQL).  (Note: Because we make use of the DBIx::Class Object
Relational Mapping [ORM] layer, out our application will be database
agnostic and can easily be used by any of the databases supported by
DBIx::Class.)

=item * 

The use of L<HTML::FormFu|HTML::FormFu> or L<HTML::FormHandler|HTML::FormHandler>
for automated form processing and validation.

=back

This tutorial makes the learning process its main priority.  For
example, the level of comments in the code found here would likely be
considered excessive in a "normal project."  Because of their contextual
value, this tutorial will generally favor inline comments over a
separate discussion in the text.  It also deliberately tries to
demonstrate multiple approaches to various features (in general, you
should try to be as consistent as possible with your own production
code).

Furthermore, this tutorial tries to minimize the number of controllers,
models, TT templates, and database tables.  Although this does result in
things being a bit contrived at times, the concepts should be applicable
to more complex environments.  More complete and complicated example
applications can be found in the C<examples> area of the Catalyst
Subversion repository at
L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/examples/>.
***Todo: update link above?


=head1 QUICK START

For those who want to get going quickly, here is a short "cookbook-style
recipe" to quickly get you up and running. Although there are many
different ways to get a Catalyst environment going, this tutorial has
been written with and tested against the Debian 6 Live CD, using the
steps in this Quick Start.

If you want, you can follow the directions in this section and then jump
right to L<Chapter 2|Catalyst::Manual::Tutorial::02_CatalystBasics> of
the tutorial. However, it would be a good idea to come back and read the
sections below the Quick Start when you have time. Or, continue reading
those other sections for suggestions if you do not wish to use the
Debian 6 Live CD.

=over 4

=item 1 

Download the C<debian-live-6.0.1-i386-rescue.iso> image from
L<http://cdimage.debian.org/cdimage/release/current-live/i386/iso-hybrid/>.

=item 2

Boot this disk, either in a physical machine, or possibly some sort
of virtual machine (using a VM can be a very handy way to practice).

=item 3

Select "C<Live>" from the initial boot menu.

=item 4

At the "C<user@debian:~$>" prompt, type:

    sudo aptitude -y install subversion

=item 5

If you want to be able to remotely SSH to this system, set a
password for root (you might want to do "dpkg -l | grep openssh-server"
to be sure the ISO image you downloaded has the SSH daemon installed...
if it's missing, do a "sudo aptitude -y install openssh-server"):

    sudo passwd
    ...

=item 6

Add the "unstable" Debian package repository:

    sudo vi /etc/apt/sources.list

Add the following line to the bottom of this file:

    deb http://ftp.us.debian.org/debian/ unstable main

=item 7

Install Catalyst and related libraries:

    sudo aptitude update
    sudo aptitude -y install libcatalyst-perl libdatetime-format-sqlite-perl \
        libdbix-class-encodedcolumn-perl sqlite3 libcatalyst-modules-perl \
        libperl6-junction-perl libcatalyst-modules-extra-perl \
        libdbix-class-timestamp-perl
    sudo aptitude clean

=item 8

Test example code:

    mkdir test
    cd test
    svn co http://dev.catalystframework.org/repos/Catalyst/trunk/examples/Tutorial/MyApp_Chapter8
    cd MyApp_Chapter8/MyApp
    CATALYST_DEBUG=0 prove -wl t
    cd

=back


=head1 VERSIONS AND CONVENTIONS USED IN THIS TUTORIAL

This tutorial was built using the following resources. Please note that
you may need to make adjustments for different environments and versions
(note that trailing zeros in version numbers are not significant and may
get dropped with some techniques for viewing them; for example, Catalyst
v5.80020 might show up as 5.8002):

=over 4

=item * 

Debian 6 (Squeeze)

=item * 

Catalyst v5.80025

=item *

Catalyst::Devel v1.28

=item * 

DBIx::Class v0.08123

=item *

Catalyst::Model::DBIC::Schema v0.41

=item *

Template Toolkit v2.22


=item *

HTML::FormFu -- v0.07002

=item * 

B<NOTE:> You can check the versions you have installed with the
following command (note the slash before the space):

    perl -M<_mod_name_>\ 999

or:

    perl -M<_mod_name_> -e 'print "$<_mod_name_>::VERSION\n"'

For example:

    perl -MCatalyst::Devel\ 999

or:

    perl -MCatalyst::Devel -e 'print "$Catalyst::Devel::VERSION\n";'

=item * 

This tutorial will assume that the web browser is located on the same
system where the Catalyst development server is running, and therefore
use a URL of C<http://localhost:3000> (the Catalyst development server
defaults to port 3000, but can be changed with the "-p" option to the
development server).  If you are running Perl on a different box than
where your web browser is located (or using a different port number via
the C<-p> I<port_number> option to the development server), then you
will need to update the URL you use accordingly.

Please Note: Depending on the web browser you are using, you might need
to hit C<Shift+Reload> or C<Ctrl+Reload> to pull a fresh page when
testing your application at various points (see
L<http://en.wikipedia.org/wiki/Bypass_your_cache> for a comprehensive
list of options for each browser).  Also, the C<-k> keepalive option to
the development server can be necessary with some browsers (especially
Internet Explorer).  ***Todo: is this still true?

=back


=head1 CATALYST INSTALLATION

Although Catalyst installation has been a challenge in the past, the
good news is that there are a growing number of options to eliminate (or
at least dramatically simplify) this concern.  Although a compelling
strength of Catalyst is that it makes use of many of the modules in the
vast repository that is CPAN, this can complicate the installation
process if you approach it in the wrong way.  Consider the following
suggestions on the most common ways to get started with a Catalyst
development environment:

=over 4

=item *

Debian

The Debian 6 Live CD represents a great way for newcomers to experiment
with Catalyst.  As a "live CD," you can simple boot from the CD, run a
few commands, and in a matter of minutes you should have a fully
function environment in which do this tutorial. B<The tutorial was fully
tested to work under Debian 6.  Although it SHOULD work under any
Catalyst installation method you might choose, it can be hard to
guarantee this.>

=over 4

=item * 

Download one of the ISO files from
L<http://cdimage.debian.org/cdimage/release/current-live/i386/iso-hybrid/>
(the current version at the time this was written was 6.0.1).  You can
pick any one of the live CD variations will work, but you may wish to
consider the following points:

=over 4

=item *

"C<debian-live-6.0.1-i386-rescue.iso>" is probably the best all-around
option for most people because it includes many extra tools such as the
GCC compiler, therefore saving RAM (every package you need to install
when running from a Live CD consumes memory because RAM disk is being
used in lieu of real disk space).  When initially booting under this
image, you may see some cryptic warning messages having to do with
various diagnostic tools it tries to load or enable, but you should be
able to safely ignore these.

=item *

"C<debian-live-6.0.1-i386-standard.iso>" is a great option because of
its compact size, but you will probably need approximately 1 GB of RAM
in the computer where you will run the tutorial.  Because the "standard"
live CD comes with with a minimal set of tools, we will have to install
extra packages (such as the GCC compiler), all of which will require RAM
when running from a live CD.

=item *

The other ISO images include different flavors of X-Windows desktop
managers.  You can select one of these if you don't mind the larger
download size and prefer a graphical environment.  Be aware that these
disks do not come with the extra tools found on the "rescue" image, so
you will need adequate RAM to be able to install them just as you would
under the "standard" image. B<Use one of the "graphical" ISO images if
you want a graphical web browser on the same machine as where you will
run the tutorial.>  (If you are using one of the non- graphical images
discussed above, you can still use a graphical web browser from another
machine and point it to your Catalyst development machine.)

=back

=item *

Boot off the CD.

=item *

Select "C<Live>" from the initial boot menu.

=item *

Once the system has booted to a "C<user@debian:~$>" prompt, first
install the Subversion client in case you want to check out the
completed chapter example code:

    sudo aptitude -y install subversion

If you want to be able to remotely SSH to this system, set a
password for root:

    sudo passwd
    ...

Then enter the following command to add the more current "unstable"
package repository so we get the latest versions of Catalyst and related
packages:

    sudo vi /etc/apt/sources.list

Add the following line to the bottom of this file:

    deb http://ftp.us.debian.org/debian/ unstable main

If you are not familiar with VI, you can move to the bottom of this file
and press the "o" key to insert a new line and type the line above.
Then press the "Esc" key followed by a colon (":"), the letters "wq" and
then the "Enter" key.  The rest of the tutorial will assume that you
know how to use some editor that is available from the Linux
command-line environment.

=item *

Install Catalyst:

    sudo aptitude update
    sudo aptitude -y install libcatalyst-perl libdatetime-format-sqlite-perl \
        libdbix-class-encodedcolumn-perl sqlite3 libcatalyst-modules-perl \
        libperl6-junction-perl libcatalyst-modules-extra-perl \
        libdbix-class-timestamp-perl

Let it install (normally about a 30 to 90-second operation) and you are
done. (Note the '\' above.  Depending on your environment, you might be
able to cut and paste the text as shown or need to remove the '\'
characters to that the command is all on a single line.)

If you are using an image other than the "rescue" ISO, you will also need
to run the following command to install additional packages:

    sudo aptitude -y install gcc make libc6-dev

If you are running from the Live CD, you probably also want to free up
some RAM disk space with the following:

    sudo aptitude clean

NOTE: While the instructions above mention the Live CD because that
makes it easy for people new to Linux, you can obviously pick a
different Debian ISO image and install it to your hard drive.  Although
there are many different ways to download and install Debian, the
"netinst" ISO image (such as "C<debian-500-i386-netinst.iso>" represents
a great option because it keeps your initial download small (but still
lets you install anything you want "over the network").

Here are some tips if you are running from a live CD and are running
out of disk space (which really means you are running out of RAM):

=over 4

=item *

Always run "C<aptitude clean>" after you install new packages to delete
the original .deb files (the files installed B<by> the .deb package
B<will> remain available, just the .deb package itself is deleted).

=item *

If you are installing modules from CPAN, you can free up some space with
"C<rm -rf /root/.cpan/*>" (change "/root/" in the previous command to
match your home directory or the location where CPAN has been configured
to perform build operations).

=item *

If necessary, you can remove the cached package information with the
command "C<rm -f /var/lib/apt/lists/*>".  You can later pull this
information again via the command "C<aptitude update>".

=item * 

You can save a small amount of space by commenting out the lines in
C</etc/apt/sources.list> that reference "deb-src" and
"security.debian.org".  If you have already done an "C<aptitude update>"
with these repositories enabled, you can use the tip in the previous
bullet to free the space up (and then do another "C<aptitude update>").

=item *

Although you can free up space by removing packages you installed since
you last booted (check out "C<aptitude remove _pkg_name_>"), don't bother
trying to remove packages already available at the time of boot. Instead
of freeing up space, it will actual consume I<more> space. (The live CD
uses these "burn in" packages right from the CD disk vs. first loading
them on the virtual RAM disk. However, if you remove them, the system
has to update various files, something that I<does> consume some space
on the virtual RAM disk.)

=back

=back

=item *

Ubuntu

Ubuntu is a popular offshoot of Debian.  It provides cutting edge
versions of many common tools, application and libraries in an
easy-to-run live CD configuration (and because a single download option
can be used for both live CD and install-to-disk usage, it keeps your
download options nice and simple).  As with Debian 6, you should be able
to generate a fully function Catalyst environment in a matter of
minutes.  Here are quick instructions on how to use Ubuntu to prepare
for the tutorial:

=over 4

=item * 

Download the Ubuntu Desktop edition and boot from the CD and/or image
file, select your language, and then "Try Ubuntu without any changes to
your computer."

=item *

Open a terminal session (click "Applications" in the upper-left corner,
then "Accessories," then "Terminal").

=item *

Add the 'universe' repositories:

    sudo gedit /etc/apt/sources.list

And remove the comments from the lines under the comments about the
'universe' repositories.

=item *

Install Catalyst:

    sudo aptitude update
    sudo aptitude install libdbd-sqlite3-perl libcatalyst-perl libcatalyst-modules-perl libconfig-general-perl

Accept all of the dependencies.  Done.

If you are running from the Live CD, you probably also want to free up
some disk space with the following:

    sudo aptitude clean

NOTE: While the instructions above mention the live CD because that
makes it easy for people new to Linux, you can obviously also use one of
the options to install Ubuntu on your drive.

=back

=item * 

Matt Trout's C<cat-install>

Available at L<http://www.shadowcat.co.uk/static/cat-install>,
C<cat-install> can be a fairly painless way to get Catalyst up and
running.  Just download the script from the link above and type
C<perl cat-install>.  Depending on the speed of your Internet connection
and your computer, it will probably take 30 to 60 minutes to install
because it downloads, makes, compiles, and tests every module.  But this
is an excellent way to automate the installation of all the latest
modules used by Catalyst from CPAN.


=item * 

Other Possibilities

=over 4

=item *

OpenBSD Packages

The 2008 Advent Day 4 entry has more information on using OpenBSD
packages to quickly build a system:
L<http://www.catalystframework.org/calendar/2008/4>.

=item *

NetBSD Package Collection on Solaris

The 2008 Advent Day 15 entry has more information on using C<pkgsrc> and
NetBSD packages on Solaris:
L<http://www.catalystframework.org/calendar/2008/15>.

=item * 

CatInABox

You can get more information at
L<http://www.catalystframework.org/calendar/2008/7> or
L<Perl::Dist::CatInABox|Perl::Dist::CatInABox>.

=item * 

Frank Speiser's Amazon EC2 Catalyst SDK

There are currently two flavors of publicly available Amazon Machine
Images (AMI) that include all the elements you'd need to begin
developing in a fully functional Catalyst environment within minutes.
See L<Catalyst::Manual::Installation|Catalyst::Manual::Installation>
for more details.

=back

=back

For additional information and recommendations on Catalyst installation,
please refer to
L<Catalyst::Manual::Installation|Catalyst::Manual::Installation>.


=head1 DATABASES

This tutorial will primarily focus on SQLite because of its simplicity
of installation and use; however, modifications in the script required
to support MySQL and PostgreSQL will be presented in the Appendix.

B<Note:> One of the advantages of using tools like Catalyst and DBIC is
that applications become much more database independent.  As such, you
will notice that only the C<.sql> files used to initialize the database
change between database systems: most of the code generally remains the
same.


=head1 WHERE TO GET WORKING CODE

Each chapter of the tutorial has complete code available as a tarball in
the main Catalyst Subversion repository (see the note at the beginning
of each part for the appropriate svn command to use).

B<NOTE:> You can run the test cases for the final code through Chapter 8
with the following commands:

    svn co http://dev.catalystframework.org/repos/Catalyst/trunk/examples/Tutorial/MyApp_Chapter8
    cd MyApp_Chapter8/MyApp
    CATALYST_DEBUG=0 prove -wl t

If you wish to include the L<HTML::FormFu|HTML::FormFu> section in your tests,
substitute C<MyApp_Chapter9_FormFu> for C<MyApp_Chapter8> in the URL
above (don't forget to "cd" out of the Ch8 directory if you ran the code above).

    svn co http://dev.catalystframework.org/repos/Catalyst/trunk/examples/Tutorial/MyApp_Chapter9_FormFu
    cd MyApp_Chapter9_FormFu/MyApp
    CATALYST_DEBUG=0 prove -wl t

You can also fire up the application under the development server that is conveniently
built in to Catalyst.  Just issue this command from the C<MyApp> directory where you
ran the test suite above:

    script/myapp_server.pl

And the application will start.  You can try out the application by
pulling up C<http://localhost:3000> in your web browser (as mentioned
earlier, change C<localhost> to a different IP address or DNS name if
you are running your web browser and your Catalyst development on
different boxes).  We will obviously see more about how to use the
application as we go through the remaining chapters of the tutorial, but
for now you can log in using the username "test01" and a password of
"mypass".


=head1 AUTHOR

Kennedy Clark, C<hkclark@gmail.com>

Please report any errors, issues or suggestions to the author.  The
most recent version of the Catalyst Tutorial can be found at
L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.

Copyright 2006-2010, Kennedy Clark, under the
Creative Commons Attribution Share-Alike License Version 3.0
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).