How to learn to build your own PHP framework

How to learn to build your own PHP framework Bridging the gap between PHP, OOP and Software Architecture Pham Cong Dinh (a.k.a pcdinh) Software Developer Hanoi PHP Day - December 2008 Hanoi - Vietnam

Introduction

A foundation member of JavaVietnam since 2003 ( http://www.javavietnam.org )

A foundation member of PHPVietnam Discussion Group since 2004 ( http://groups.google.com/group/phpvietnam )

Lead web developer with World’Vest Base Inc.

Java is my first love since 1999

PHP is my real lover since 2003. I love the way PHP community works

Sometimes I works on Python, Ruby, Erlang

I am a strong believer in dynamic programming languages, JavaScript, web standards, convergence of web as a platform and Outsourcing 2.0

I spent 2 years to play with my framework named Pone (PHP One)

Objectives

Where is PHP now? It is changing.

Enterprise oriented: which is driven by Yahoo, Facebook, Zend, Sun/MySQL, Oracle, OmniTI … PHP is too big. It can not just be ignored

Object Oriented Programming adoption

Increased complexity of web applications

Web vs. Adobe Air, MS Silverlight, JavaFX, Google Native Client

Trends Will Move Applications to the Web: Consumer Innovation Setting the Pace, Rise of the Power Collaborator, New Economics of Scale for IT, Barriers to Adoption Are Falling

Scale-out wins

Understanding what framework designers think

Building up shared mindsets

Providing food for thought

Agenda – 40 slides

Making judgments

Top notch frameworks and their shortcomings

A broader view on your framework

Lessons to learn

Making judgments

Common wisdom: Reinventing the wheel

Good

You know it inside and out

You control its pace

It fits your needs. Sometimes, your need is unique

It teaches you how the world around you works

License: This is why GPL is sometime a bad thing

Bad

You may not as good as other ones

No community

No outside contributors

Reinventing the square wheel

Making judgments

To develop a framework is just like to set up a business

Think of your limitation: time, resources, knowledge to build/test/document/maintain your own mental baby

Know your team: how to train them

Know the market : known frameworks in the market. Sometimes your needs are satisfied to some extent in several little-known frameworks

Starts with pencil and paper: its components and how they interact

Starts with API: learn how to design an API first

You never do it right from day one

Know the market

CakePHP shortcomings

Zend Framework shortcomings

Third party frameworks shortcomings

Know the market - CakePHP

Misleading terms: plugin, model…

Plugin: CakePHP allows you to set up a combination of controllers, models, and views and release them as a packaged application

Too database centric: CakePHP naming convention is driven by table names, not dependency injection mechanism.

Admin routing sucks: why do we need one-and-only backend for the whole application/plugin/etc…?

Flat application structure: plugin/controller/action and no more.

Global space constants

No elegant way to change media file (css, javascript, meta content) on each layout page, controlled by a Controller.

<head> <?php echo $html->charset(); ?> <title> <?php echo $title_for_layout; ?> </title> <?php echo $html->css('cake.generic'); echo $javascript->link('prototype-1.6.0.2'); echo $scripts_for_layout; echo $html->meta('icon','/myapp/img/favicon.ico', array ('type' =>'icon')); ?> </head>

loadModel(), loadController() are not about dependency injection

E.x: You want to provide access to a model from a Component Say you have a model called FooBar in a file called foo_bar.php

loadModel ('FooBar');

$this ->FooBar = & new FooBar();

loadModel() maybe deprecated in favor of

App::import ('Model', 'ModelName');

beforeFilter(), afterFilter() are coupled with a certain controller (controller is a heavy object. It should avoid being hit too soon)

<?php class AppController extends Controller { var $beforeFilter = array ( 'checkAccess' ); var $components = array ( 'Acl' ); function checkAccess() { } } ?>

Reuse of view via elements with requestAction() is bad and expensive

The dispatcher is called for each call to a controller (routing, figures out what (Plugin)/Controller/Action is request, loops through all $paths->controllerPaths files, to figure out what Controller to load)

The controller is set up again

Behavior: controllerActAsModel

Controller is an interface to another tier

Controller is not designed to provide data for internal components

Cache unfriendly

Caching hits its hard time because there is no way to get generated view content

<?php

$this->element('helpbox', array("cache" => array('time'=> "+7 days",'key'=>'unique value')));

?>

What about URL-based caching, session/cookie-based caching, geo-based caching, date-based caching

(there are a lot of things to tell about CakePHP but it is all for today)

Know the market – Zend Framework

Zend Framework tries to be a better PEAR

Powered by a solid foundation

A solid and controllable licensing (CLA)

More strictly controlled development environment

Enterprise-oriented class library

A well-defined roadmap and versioning

Zend Framework is a glue framework or framework-oriented class library

Zend Framework is extremely big and bloated

Zend Framework 1.6.2: 1261 file, 267 folders

Zend_Mail: 33 files

Zend_Pdf: 89 files

Zend_Controller: 50 files

Zend_View: 57 files

Drupal includes folders: 33 files

Zend Framework is designed most like Java frameworks

Small class file

Lot of classes: object graph is hard (see next)

Atomic responsibility

Strongly embrace design patterns

Everything is an object, even a HTML button or checkbox. The same to Java (see Apache Wicket, Tapestry, JBoss Seam)

class Zend_View_Helper_FormReset extends Zend_View_Helper_FormElement

{

public function formReset($name = '', $value = 'Reset', $attribs = null)

{

$info = $this->_getInfo($name, $value, $attribs);

extract ($info); // name, value, attribs, options, listsep, disable

// check if disabled

$disabled = '';

if ($disable) {

$disabled = ' disabled="disabled"';

}

// get closing tag

$endTag = '>';

if ($this->view->doctype()->isXhtml()) {

$endTag = ' />';

}

// Render button

$xhtml = '<input type="reset"'

. ' name="' . $this->view->escape($name) . '"'

. ' id="' . $this->view->escape($id) . '"'

. $disabled;

. . . . . . . . .

}

}

What Zend Framework brings

Lot of files are loaded per request which is a bad thing for a dynamic, interpreted language and stateless platform like PHP

Much more memory usage

Bad thing for PHP memory management model in which memory is allocated in small chunks

Zend Framework code: There are lot of require_once() call inside an if statement which is bad for opcode caching mechanism

Zend Framework leaves shared hosting in the cold.

700 sites per server are quite normal

No control over file system optimization

No control over memory

No control over opcode caching

A glue framework requires you to know every concrete class and how to use them in a application life cycle

A lot of things to consider means bootstrapping is a mess

define ('ROOT_DIR', dirname(dirname(dirname(__FILE__))));

define ('APP_DIR',dirname(dirname(__FILE__)));

set_include_path ('.' . PATH_SEPARATOR . APP_DIR . '/lib/' . PATH_SEPARATOR . APP_DIR . '/application/default/models/' . PATH_SEPARATOR . ROOT_DIR . '/shared/lib/' . PATH_SEPARATOR . get_include_path());

//This requires that your Zend library lies in ROOT_DIR/shared/lib/

//make classes autoload without doing require

require_once ('Zend/Loader.php');

Zend_Loader::registerAutoload();

if ( defined ('ENV') !== TRUE) {

define ('ENV','production'); //change staging to production to go to production settings

}

$config = new Zend_Config_Xml(APP_DIR . '/config/config.xml', ENV);

Zend_Registry::set('config',$config);

//init session

$session = new Zend_Session_Namespace($config->session_name);

Zend_Registry::set('session',$session);

Zend_Db_Table::setDefaultAdapter(Zend_Db::factory(Zend_Registry::get('config')->database));

/**

* Init the Smarty view wrapper and set smarty suffix to the view scripts.

*/

$view = new EZ_View_Smarty($config->smarty->toArray());

// use the viewrenderer to keep the code DRY instantiate and add the helper in one go

$viewRenderer = Zend_Controller_Action_HelperBroker::getStaticHelper('ViewRenderer');

$viewRenderer->setView($view);

$viewRenderer->setViewSuffix($config->smarty->suffix);

/**

* Set inflector for Zend_Layout

*/

$inflector = new Zend_Filter_Inflector(':script.:suffix');

$inflector->addRules(array(':script' => array ('Word_CamelCaseToDash', 'StringToLower'), 'suffix' => $config->layout->suffix));

// Initialise Zend_Layout's MVC helpers

Zend_Layout::startMvc( array ('layoutPath' => ROOT_DIR.$config->layout->layoutPath,

'view' => $view,

'contentKey' => $config->layout->contentKey,

'inflector' => $inflector));

$front = Zend_Controller_Front::getInstance();

$front->setControllerDirectory(array(

'default' => '../application/default/controllers',

'blog' => '../application/blog/controllers',

));

$front->throwExceptions(true);

// enable logging to default.log

$writer = new Zend_Log_Writer_Stream(APP_DIR.'/data/log/default.log');

$logger = new Zend_Log($writer);

// give easy access to the logger

Zend_Registry::set('logger', $logger);

try {

$front->dispatch();

} catch (Exception $e) {

echo nl2br($e->__toString());

}

Zend Framework is different.

It is not a solid application framework like CakePHP, it is designed to be a platform on which other frameworks are built

Technical details should be mentioned in another talk (enough for today)

MVC Push or Pull

MVC Push or Passive View

<?php // Load the Savant3 class file and create an instance. require_once 'Savant3.php'; $tpl = new Savant3(); // Create a title. $name = "Some Of My Favorite Books"; // Generate an array of book authors and titles. $booklist = array( array( 'author' => 'Hernando de Soto', 'title' => 'The Mystery of Capitalism' ), array( 'author' => 'Neal Stephenson', 'title' => 'Cryptonomicon' ), array( 'author' => 'Milton Friedman', 'title' => 'Free to Choose' ) ); // Assign values to the Savant instance. $tpl->title = $name; $tpl->books = $booklist; // Display a template using the assigned values. $tpl->display('books.tpl.php'); ?>

MVC Push or Pull

MVC Pull or so-called HMVC (see next): break a big controller into small ones

MVC Push or Pull: HMVC implementation

Master Controller

/**

* Show the home page

*

* @link http://www.wvbresearch.com/home/index/index

* @name index

* @access public

*/

public function indexAction()

{

// Attach placeholder: the name of ElementGroup

$this->_layout->registerBody('homeIndex');

// Set content for the response

$this->_response->setContent($this->_layout->render('index3col'));

}

Group Controller

class Group_HomeIndex extends Pone_View_ElementGroup

{

/**

* Elements in in this group

*

* @var array

*/

protected $_elementsInGroup = array(

'homeTopNegativeEpsSurprises', 'homeTopPositiveEpsSurprises',

'homeIntroduction', 'brokerRatingsUpgrades', 'homeAnalystEstimatesSearchBox',

'homeResearchReportSearchBox', 'latestResearchReports'

);

protected $_templateFile = 'homeIndex';

public function setup()

{

}

}

Element Controller

class Element_LatestResearchReports extends Pone_View_Element

{

protected $_templateFile = 'latestResearchReportsOnHome';

/**

* List of recent research reports

*

* @var Pone_DataSet

*/

public $researchReports;

public function setup()

{

$module = Pone::getContext()->getFront()->getRequest()->getModuleName();

$numberOfItems = 7;

if ('home' !== $module)

{

$this->_templateFile = 'latestResearchReports';

$numberOfItems = 10;

}

$dbConn = Pone_Action_Helper_Database::getInstance()->getConnection('oracleweb', true);

$researchReportDs = ResearchReportDatabaseService::getInstance($dbConn);

$this->researchReports = $researchReportDs->findRecentList($numberOfItems);

}

}

Element Controller template

< div class =" featureBlockHeader ">

< h2 >Latest reports</ h2 >

</ div >

< div class=" textBox ">

< div class=" textBoxContent ">

<?php if ( true === $this->researchReports->isReadable()): $iter = $this->researchReports->getIterator(); ?>

< ul class=" imgList ">

<?php foreach ($iter as $report): ?>

< li ><a href="research/detail/view/rpid/<?php echo $report->get('report_id') ?>"><?php echo $report->get('title'); ?></a></li>

<?php endforeach; ?>

</ul>

<?php else: echo $this->researchReports->getMessage(); endif; ?>

</ div >

</ div >

IDE support

Code completion rocks

MVC Push is bad for view data documentation

Zend_Registry is bad for code completion

Zend_Registry :: set('logger', $logger);

Think of interface because implementing a way to load dynamic class from a variable or an array element.

Learn how to write DocBlock

Core feature set

MVC framework

Model layer: DBO, File handling/transformation, business rules, workflows, search, messaging, memory, remote resource access …

Validation framework instead of form handling

Unified directory structure: model classes, controllers, views (page fragments, layouts), plugins, filters, custom exceptions, helpers

Session

Authentication and ACL: Abstract and extensible

HTTP Digest

Database backed

SAML/SSO

Serializable Unified Session User Object

Core feature set

Validation framework

class Form_Signup extends Pone_Form_Input

{

. . . . . .

public function onPost()

{

// Email

$emailRules = array(

Pone_Form_Rule::EMAIL => array('feedback' => _t('common.error.email.notvalid'))

);

$this->setValidationRule('email', $emailRules);

// Email 2

$email2Rules = array(

Pone_Form_Rule::STRING_EQUAL => array('feedback' => _t('common.error.reemail.not_match'),

'reference' => 'email')

);

$this->setValidationRule('email2', $email2Rules);

// password

$passwordRules = array(

Pone_Form_Rule::NOT_EMPTY => array('feedback' => _t('common.error.password.empty'))

);

$this->setValidationRule('password', $passwordRules);

// password 2

$password2Rules = array(

Pone_Form_Rule::STRING_EQUAL => array('feedback' => _t('common.error.repassword.not_match'),

'reference' => 'password')

);

$this->setValidationRule('password2', $password2Rules);

}

}

Much more things that need to take into account

Behavior layer

Caching

Distributed caching

Local caching

Dependency Injection framework

Internationalization

(enough for today)

Lessons to learn

Take your hand dirty please.

Singleton is bad thing when dependency injection and unit testing are taken into consideration

can't replace it with an interface

Factory allows for both discovery and instance management of the service providers

Final classes should keep singleton objects

$dbConn = Pone_Action_Helper_Database :: getInstance ()->getConnection('oracleweb', true);

$researchReportDs = ResearchReportDatabaseService :: getInstance ($dbConn);

$this->researchReports = $researchReportDs->findRecentList($numberOfItems);

Lessons to learn

Factory and interface make good things

Factory and Adapter are good for service providers

$conn = Pone_Database_ConnectionFactory::getConnection($config);

$stmt = $conn->createStatement();

$stmt ->addBatch("INSERT INTO test2 VALUES (1007, 'pcdinh1007', 1)");

$conn ->beginTransaction();

$updateCounts = $stmt->executeBatch();

Lessons to learn

Fluent interface/object chaining sometimes is a bad thing

Law of Demeter

$module = Pone::getContext()->getFront()->getRequest()->getModuleName();

Lessons to learn

Don’t think DAO or ActiveRecord, think Domain Respository

Lessons to learn

An interface between Model and Controller must be defined

Model class returns an array: bad thing. How to catch errors and deal with them in the view template

Lessons to learn

Dependency Injection

Does all injection through the constructor

$libBasePath = $basePath.'/libs';

$appBasePath = $basePath.'/apps';

Pone::executeContext( new BenchmarkContext() , $basePath, $appBasePath, $libBasePath);

OR

$front->setRequest(new Pone_Request( new Pone_Request_SimpleUrlParser() ));

Use Template Method design pattern

Seam

if (session_id() === '' && PHP_SAPI != 'cli')

{

Pone::getContext()->loadSessionUserClass();

$started = session_start(); // PHP 5.3: returns false or true

$this->_started = true;

}

Use XML/YAML like in Spring, Symfony which is somewhat heavy in an interpreted language like PHP

Design by Interface

Rule: Don’t call me, I will call you

Template Method

Convention over configuration

That’s end for today

Thanks you

Any question?

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