Real world dependency injection - DPC10
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Real world dependency injection - DPC10 Real world dependency injection - DPC10 Presentation Transcript

  • Real World Dependency Injection Stephan Hochdörfer, bitExpert AG "Dependency Injection is a key element of agile architecture" Ward Cunningham
  • Agenda 1. About me 2. What is Dependency Injection? 3. Real World examples 4. Pros & Cons 5. Questions
  • About me  Stephan Hochdörfer, bitExpert AG  Department Manager Research Labs  enjoying PHP since 1999  S.Hochdoerfer@bitExpert.de  @shochdoerfer
  • What is Dependency Injection? What is Dependency?
  • What is Dependency Injection? What is Dependency?  Application Layer  Data Access layer  Business logic layer  ...  External components  Framework classes  Webservices  ...
  • What is Dependency Injection? Why are Dependencies bad?
  • What is Dependency Injection? Why are Dependencies bad? „new“ is evil!
  • What is Dependency Injection? Why are Dependencies bad?  Tightly coupled code  Hard to re-use components  Hard to test components, no isolation
  • What is Dependency Injection? Simple Dependency Main Required class class
  • What is Dependency Injection? Complex Dependency Required class Main Required class class Required class
  • What is Dependency Injection? Very complex Dependency Database Required class External Main Required resource class class Required class Required Required Webservice class class
  • What is Dependency Injection? Very complex Dependency Database Required class External Main Required resource class class Required class Required Required Webservice class class
  • What is Dependency Injection? Very complex Dependency Database Required class External Main Required resource class class Required class Required Required Webservice class class
  • What is Dependency Injection? How to Manage Dependencies?
  • What is Dependency Injection? How to Manage Dependencies? You don`t need to. The Framework does it all!
  • What is Dependency Injection? How to Manage Dependencies? Simple Container vs. Full stacked Framework
  • What is Dependency Injection? What is Dependency Injection?
  • What is Dependency Injection? What is Dependency Injection? Consumer
  • What is Dependency Injection? What is Dependency Injection? Consumer Dependencies
  • What is Dependency Injection? What is Dependency Injection? Consumer Dependencies Container
  • What is Dependency Injection? What is Dependency Injection? Consumer Dependencies Container
  • What is Dependency Injection? Types of Dependency Injection Type 1: Constructor injection <?php class MySampleService implements IMySampleService { /** * @var ISampleDao */ private $oSampleDao; public function __construct(ISampleDao $poSampleDao) { $this->oSampleDao = $poSamleDao; } } ?>
  • What is Dependency Injection? Types of Dependency Injection Type 2: Setter injection <?php class MySampleService implements IMySampleService { /** * @var ISampleDao */ private $oSampleDao; public function setSampleDao(ISampleDao $poSampleDao) { $this->oSampleDao = $poSamleDao; } } ?>
  • What is Dependency Injection? Types of Dependency Injection Type 3: Interface injection <?php class MySampleService implements IMySampleService, IApplicationContextAware { /** * @var IApplicationContext */ private $oCtx; public function setApplicationContext(IApplicationContext $poCtx) { $this->oCtx = $poCtx; } } ?>
  • What is Dependency Injection? Configuration Types Type 1: Annotations <?php class MySampleService implements IMySampleService { /** * @var ISampleDao */ private $oSampleDao; /** * @Inject */ public function __construct(ISampleDao $poSampleDao) { $this->oSampleDao = $poSamleDao; } } ?>
  • What is Dependency Injection? Configuration Types Type 1: Annotations <?php class MySampleService implements IMySampleService { /** * @var ISampleDao */ private $oSampleDao; /** * @Inject * @Named('TheSampleDao') */ public function __construct(ISampleDao $poSampleDao) { $this->oSampleDao = $poSamleDao; } } ?>
  • What is Dependency Injection? Configuration Types Type 2: External configuration via XML <?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.bitexpert.de/schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.bitexpert.de/schema/ http://www.bitexpert.de/schema/bitFramework-beans.xsd"> <bean id="SampleDao" class="SampleDao"> <constructor-arg value="app_sample" /> <constructor-arg value="iSampleId" /> <constructor-arg value="BoSample" /> </bean> <bean id="SampleService" class="MySampleService"> <constructor-arg ref="SampleDao" /> </bean> </beans>
  • What is Dependency Injection? Configuration Types Type 2: External configuration via YAML services: SampleDao: class: SampleDao arguments: ['app_sample', 'iSampleId', 'BoSample'] SampleService: class: SampleService arguments: [@SampleDao]
  • What is Dependency Injection? Configuration Types Type 3: PHP Configuration <?php class BeanCache extends bF_Beanfactory_Container_PHP_ACache { protected function createSampleDao() { $oBean = new SampleDao('app_sample', 'iSampleId', 'BoSample'); return array("oBean" => $oBean, "bSingleton" => "1"); } protected function createMySampleService() { $oBean = new MySampleService($this->getBean('SampleDao')); return array("oBean" => $oBean, "bSingleton" => "1"); } ?>
  • What is Dependency Injection? Cache, Cache, Cache! 180 160 140 120 100 80 60 40 20 0 XML no Caching XML with Caching PHP PHP compiled Requests per Second meassured via Apache HTTP server benchmarking tool
  • Real world examples "High-level modules should not depend on low-level modules. Both should depend on abstractions." Robert C. Martin
  • Real World examples Unittesting made easy <?php require_once 'PHPUnit/Framework.php'; class ServiceTest extends PHPUnit_Framework_TestCase { public function testSampleService() { $oSampleDao = $this->getMock('ISampleDao'); // run test case $oService = new MySampleService($oSampleDao); $bReturn = $oService->doWork(); // check assertions $this->assertTrue($bReturn); } } ?>
  • Real World examples One class, multiple configurations Implementation Live Working <?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.bitexpert.de/schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.bitexpert.de/schema/ http://www.bitexpert.de/schema/bitFramework-beans.xsd"> <bean id="ExportLive" class="MyApp_Service_ExportManager"> <constructor-arg ref="DAOPageLive" /> </bean> <bean id="ExportWorking" class="MyApp_Service_ExportManager"> <constructor-arg ref="DAOPageWorking" /> </bean> </beans>
  • Real World examples One class, multiple configurations II <?php class Promio_Action_Account_Auth extends bF_Mvc_Action_AFormAction { private $oAccountManager; private $iType; public function __construct(Promio_Service_IAccountManager $poAccountManager) { $this->oAccountManager = $poAccountManager; } public function setType($piType) { $this->iType = (int) $piType; } protected function processFormSubmission(bF_Bo_ABo $poBOFormBackingObject) { $oMaV = new bF_Mvc_ModelAndView($this->getSuccessView(), true); try { $poBOFormBackingObject->setType($this->iType); $this->oAccountManager->save($poBOFormBackingObject); } catch(bF_Service_ServiceException $oException) { $oMaV = new bF_Mvc_ModelAndView($this->getFailureView(), true); } return $oMaV; } } ?>
  • Real World examples Mocking external services Consumer Connector Webservice IConnector interface <?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.bitexpert.de/schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.bitexpert.de/schema/ http://www.bitexpert.de/schema/bitFramework-beans.xsd"> <bean id="Consumer" class="MyApp_Service_Consumer"> <constructor-arg ref="Connector" /> </bean> </beans>
  • Real World examples Mocking external services alternative Local Consumer Connector filesystem IConnector interface <?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.bitexpert.de/schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.bitexpert.de/schema/ http://www.bitexpert.de/schema/bitFramework-beans.xsd"> <bean id="Consumer" class="MyApp_Service_Consumer"> <constructor-arg ref="AltConnector" /> </bean> </beans>
  • Real World examples Clean, readable code <?php class Promio_Action_News_Delete extends bF_Mvc_Action_AAction { /** * @var Promio_Service_INewsManager */ private $oNewsManager; public function __construct(Promio_Service_INewsManager $poNewsManager) { $this->oNewsManager = $poNewsManager; } protected function execute(bF_Mvc_Request $poRequest) { try { $this->oNewsManager->delete((int) $poRequest->getVar('iNewsId')); } catch(bF_Service_ServiceException $oException) { } $oMaV = new bF_Mvc_ModelAndView($this->getSuccessView(), true); return $oMaV; } } ?>
  • Real World examples No framework dependency <?php class MySampleService implements IMySampleService { /** * @var ISampleDao */ private $oSampleDao; public function __construct(ISampleDao $poSampleDao) { $this->oSampleDao = $poSamleDao; } public function getSample($piSampleId) { try { return $this->oSampleDao->readByPrimaryKey((int) $piSampleId); } catch(DaoException $oException) { } } } ?>
  • Pros & Cons Benefits  Good for agile development  Reducing amount of code  Helpful for Unit testing  Loose coupling  Least intrusive mechanism  Switching implementations by changing configuration  Separation of glue code from business logic  Clean view on the code  Separate configuration from code  Getting rid of boilerpate configuration code
  • Pros & Cons Cons  To many different implementations, no standard today!  Bucket, Crafty, FLOW3, Imind_Context, PicoContainer, Pimple, Phemto, Stubbles, Symfony 2.0, Sphicy, Solar, Substrate, XJConf, Yadif, Zend_Di (Proposal), Lion Framework, Spiral Framework, Xyster Framework, …  No JSR 330 for PHP  Simple Containers vs. fully-stacked Framework  No dependency from application to Container!  Developers need to be aware of configuration ↔ runtime
  • http://joind.in/1553