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

Know the market - CakePHP 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>

Know the market - CakePHP 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');

Know the market - CakePHP 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() { } } ?>

Know the market - CakePHP 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

Know the market - CakePHP 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

Know the market – Zend Framework 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

Know the market – Zend Framework 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; . . . . . . . . . } }

Know the market – Zend Framework 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

Know the market – Zend Framework 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

Know the market – Zend Framework 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());

Know the market – Zend Framework // 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()); }

Know the market – Zend Framework 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)

A broader view on your framework 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'); ?>

A broader view on your framework MVC Push or Pull MVC Pull or so-called HMVC (see next): break a big controller into small ones

A broader view on your framework

A broader view on your framework 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')); }

A broader view on your framework MVC Push or Pull: HMVC implementation 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() { } }

A broader view on your framework MVC Push or Pull: HMVC implementation 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); } }

A broader view on your framework MVC Push or Pull: HMVC implementation 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 >

A broader view on your framework 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

A broader view on your framework 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

A broader view on your framework 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); } }

A broader view on your framework 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)"); $stmt ->addBatch("INSERT INTO test2 VALUES (1009, 'pcdinh1009', 1)"); $stmt ->addBatch("INSERT INTO test2 VALUES (1010, 'pcdinh1010', 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

How to learn to build your own PHP framework

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