catalyst overview

8/8/2019 Catalyst Overview

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INTRODUCTION TO CATALYST Object oriented Perl MVC Framework

By

BUNTY RAY


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WHAT IS MVC?

Model View Controller: Architecture that separates an application's data model,

user interface, and control logic into 3 distinct components

modifications to one component can be made with minimal

impact to the others.

Responsibility model - domain-specific representation of the information

on which the application operates (database)

view - renders the model into a form suitable for

interaction, typically a user interface (html) controller- responds to events and invokes changes on the model

and/or the view


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WHAT IS CATALYST?

A framework for development of web application

using Model-View-Controller pattern: Promotes the re-use of existing Perl modules that already handle common web

application

Catalyst is controller

View: Template::Toolkit, Mason, HTML::Template, etc.

Model: Class::DBI, Tangram, Rose::DB, etc.

platform independent (really!)

Engines: CGI, FastCGI, mod_perl (1.3 and 2.0), self restarting

development engine


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WHY CATALYST?

Doesn't aim to provide end to end solution (RnR)

Flexibility use different components as M or V Reusability plugins (extends runtime functionality):

session, form validation, static files serving, unicode

Built-in development tools:

Self-restarting development web server on dev's machine Distribute the application as CPAN module

Framework for auto and unit tests

Doesn't need web server to generate pages


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CATALYST ARCHITECTURE FLOW


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INSTALLING AND RUNNING

Installation from CPAN

$ perl -MCPAN -e 'install Task::Catalyst Confirm successful installation catalyst.pl

(Before proceeding please check the next slide to confirm the output) Creating stub application $ catalyst.pl MyApp

# output omitted [Next Slide] $ cd MyApp $ script/myapp_create.pl controller Library::Login Running $ script/myapp_server.pl Open in browser: http://localhost:3000/library/login/

C:\Users\BUNTY\

op\Server-Starte


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CHECK IF INSTALLED PROPERLY

When you execute catalyst.pl , ensure you see the bellow output

developer@dev01-th:~$ catalyst.pl

Usage:catalyst.pl [options] application-name

'catalyst.pl' creates a skeleton for a new application, and allows youto upgrade the skeleton of your old application.

Options:-force don't create a .new file where a file to be created exists

-help display this help and exit-makefile only update Makefile.PL-scripts only update helper scripts-short use short names, M/V/C instead of Model/View/Controller.

application-name must be a valid Perl module name and can include "::",which will be converted to '-' in the project name.

Examples:catalyst.pl My::Appcatalyst.pl MyApp

To upgrade your app to a new version of Catalyst:

catalyst.pl -force -scripts MyApp


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CATALYST URL


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APPS

developer@dev01-th:~$ catalyst.pl MyApp

created "MyApp"

created "MyApp/script"created "MyApp/lib"

created "MyApp/root"

created "MyApp/root/static

created "MyApp/root/static/images"

created "MyApp/t"

created "MyApp/lib/MyApp"

created "MyApp/lib/MyApp/Model"

created "MyApp/lib/MyApp/View"

created "MyApp/lib/MyApp/Controller"

created "MyApp/myapp.conf"

created "MyApp/lib/MyApp.pmcreated "MyApp/lib/MyApp/Controller/Root.pm"

created "MyApp/README"

created "MyApp/Changes"

created "MyApp/t/01app.t"

created "MyApp/t/02pod.t"


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CONTINUED

created "MyApp/t/03podcoverage.t"

created "MyApp/root/static/images/catalyst_logo.png"

created "MyApp/root/static/images/btn_120x50_built.png"

created "MyApp/root/static/images/btn_120x50_built_shadow.png"

created "MyApp/root/static/images/btn_120x50_powered.png"

created "MyApp/root/static/images/btn_120x50_powered_shadow.png"

created "MyApp/root/static/images/btn_88x31_built.png"

created "MyApp/root/static/images/btn_88x31_built_shadow.png"

created "MyApp/root/static/images/btn_88x31_powered.png"created "MyApp/root/static/images/btn_88x31_powered_shadow.png"

created "MyApp/root/favicon.ico

created "MyApp/Makefile.PL"

created "MyApp/script/myapp_cgi.pl"

created "MyApp/script/myapp_fastcgi.pl"

created "MyApp/script/myapp_server.pl"

created "MyApp/script/myapp_test.pl"

created "MyApp/script/myapp_create.pl"


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DIRECTORY

drwxr-xr-x 2 developer developer 4096 2010-08-22 01:06 script

-rw-r--r-- 1 developer developer 52 2010-08-22 01:06 README-rw-r--r-- 1 developer developer 133 2010-08-22 01:06 myapp.conf

-rw-r--r-- 1 developer developer 144 2010-08-22 01:06 Changes

drwxr-xr-x 3 developer developer 4096 2010-08-22 01:20 lib

drwxr-xr-x 4 developer developer 4096 2010-08-22 01:49 root

drwxr-xr-x 4 developer developer 4096 2010-08-22 01:53 inc-rw-r--r-- 1 developer developer 488 2010-08-22 01:53 META.yml

-rw-r--r-- 1 developer developer 26474 2010-08-22 01:53 Makefile

-rw-r--r-- 1 developer developer 0 2010-08-22 01:54 pm_to_blib

drwxr-xr-x 8 developer developer 4096 2010-08-22 01:54 blib

-rw-r--r-- 1 developer developer 624 2010-08-22 01:55 Makefile.PL

drwxr-xr-x 2 developer developer 4096 2010-08-22 02:19 t


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CONTINUED

Makefile.PL

This script generates a Makefile to build , test and install your application. Thisfile is invoked (perl Makefile.Pl) after you executed the command

catalyst.pl MyApp (output attached)

It also contains a list of your applications CPAN dependencies andautomatically install them.

Changes This is simply a text file where you can document changes to your application.This can be used as an help for end user or other developers.

R EADME

Its a text with information on your application.

myapp.conf This is the main configuration file for the application which is loaded when yourapplication starts.

C:\Users\BUNTY\p\Running_Mak


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CONTINUED/lib Directory

Its the hear of the application. This directory contains a file MyApp.pm, which

defines the namespace and inheritance that are necessary to make this Catalystapplication. It also contains list of plugins to load application specificconfiguration.

/lib directory contains 3 key directories

Controller , View and Model

Catalyst loads the Controller, Model and View from these directories.

Basically the default Controller is Root.pm . This will handle all root level ( / )URLs. This is where the code that generates the welcome page is located.

MyApp under /lib is like a namespace of a module. The application is createdwith whatever argument to catalyst.pl.

e.g. catalyst.pl MyCompany::HR::Timeslips

This will create the application with namespace MyCompany::HR::Timeslipsand in file system its will be /lib/MyCompany/HR/Timeslips


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CONTINUED

/root Directory

Contains the template and other non code support file.

Contains a /static sub directory which holds static contents like image files andstylesheet, css files etc.

/script Directory

Contains scripts needed to run, test and modify your application

(i) myapp_server.pl->This is the development server (a self-contained HTTPD server) that you canuse to run your application while you are developing it.

(ii) myapp_cgi.pl->

This is a script for deploying your application with a web server that can not use

mod_perl or FastCGI. Its very slow and low performer, so should be used as thelast option.

(iii) myapp_fastcgi.pl ->

Allows you to run your application in a FastCGI server.(Production Mode)


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CONTINUED

(iv) myapp_test.pl ->

Basically used to test an action without opening browser.(v) myapp_create.pl ->

This is a helper script. This is customized version of the catalyst.pl for yourapplication. It can be used to create Controller, Model and View.

/t Directory

The t directory is where your application's automatic tests are stored.

01app.t, which is a test that passes if your application compiles.

02pod.t, which will pass if your Plain Old Documentation (POD) embeddedAPI documentation, inside your application, is valid.

03podcoverage.t, which tests that every public function in your applicationhas some documentation.

You can run the tests in this command by running make test, afterMakefile.PL creates the Makefile.


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HANDLING URL REQUEST

When a user makes a request using Browser, Catalyst looks for the appropriatemethod that can handle the request within package called Controller.

http://url/controller.action

(hello) (test)

/lib/appname/Controller/Hello.pm

e.g. http://192.168.187.132:3000/hello/index.html

Will match the hello Controller (Hello.pm) index will matchthe subroutine

within the Hello.pm
http://url/controller.actionhttp://192.168.187.132:3000/hello/index.htmlhttp://192.168.187.132:3000/hello/index.htmlhttp://url/controller.actionhttp://url/controller.action


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CREATING A CONTROLLER

perl script/myapp_create.pl controller Hello

This will create /lib/MyApp/Controller/Hello.pm

package MyApp::Controller::Hello;

use strict;

use warnings;

use parent 'Catalyst::Controller';

=head1 NAMEMyApp::Controller::Hello - Catalyst Controller

=head1 DESCRIPTION

Catalyst Controller.

=head1 METHODS=cut

=head2 index

=cut

C:\Users\BUNTY\op\Creating A c


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CONTINUED

sub index :Path :Args(0) {

my ( $self, $c ) = @_;

$c->response->body('Matched MyApp::Controller::Hello in Hello.');

}

=head1 AUTHOR

developer,,,

=head1 LICENSE

This library is free software, you can redistribute it and/or modify

it under the same terms as Perl itself.=cut

1;

At the top is the package declaration (so Perl knows what this module is

named), and then some use statements (to tell Perl that this module uses

Moose). Then, BEGIN {extends 'Catalyst::Controller'; } to tell Moose/Perl thatthis module is a Catalyst Controller. Next, there is some POD (the text starting

with =) that you can fill in to provide some API documentation (see man

perlpod for the syntax.


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CONTINUED

Let us check what just happened by running the server with the following

command: perl script/myapp_server.pl

[debug] Loaded Path actions:

. -------------------------------------+--------------------------------------.

| Path | Private |

+-------------------------------------+--------------------------------------+| / | /index |

| / | /default |

| /hello | /hello/index |

Opening the URL http://localhost:3000/hello will show you the following:

Matched MyApp::Controller::Hello in Hello


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ADDING A VIEW

Now the URL is mapped to Controllers method. Its time now to show someHTML content using View.

View is a system that defines how content can be rendered. Currently we willmake use of Template Toolkit templating system to enable TT view for our HTMLpage. (Template Toolkit module is available with Catalyst)

Step 1:

Remove the below line from Hello.pm Controller under /lib/MyApp/Controllerlocation from the subroutine index().

$c ->response ->body()Catalyst knows how to take care of forwarding the response to the default viewafter the Controllers execution.

Step 2:

Now create the view

perl script/myapp_create.pl view TT TTThis means create a view called View/TT.pm (1st TT) based on the standardCatalyst::View::TT (2nd TT). Technically this means we can create as many viewsof Catalyst::View:TT with different names.

C:\Users\BUNTY\op\Creating a T


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CONTINUEDStep 3:

Now update the Makefile.Pl with the below content under requires section. This step is

not mandatory, but is advised to do since it will be useful when you are migrating theapplication to a different machine.

requires Catalyst::View::TT =>0;

Now run the below commands

(a) perl Makefile.PL

(b) make

Step 4:

Now create a template under /root/hello directory with a name index.tt

/root is the default location from where Catalyst::View::TT will look for templates.

Now add content to the .tt file to display

hello , world!

C:\Users\BUNTY\p\Running_Mak

C:\Users\BUNTY\p\Running_mak

TML Document


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catalyst overview

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