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![sfServiceContainer Subclass <?php class UserRepositoryContainer extends sfServiceContainer { protected function getUserRepositoryService() { $container = new DataAccessLayer($this['repository.config']); return $container; } }](https://image.slidesharecdn.com/iocwithphp-110812014234-phpapp01/75/IoC-with-PHP-32-2048.jpg)
IoC with PHP
- 1. IoC with PHP Chris Weldon Dallas TechFest 2011
- 2. Before We Begin http://bit.ly/rf1pxR git://github.com/neraath/ioc-php-talk.git
- 3. Your Guide: ChrisWeldon • Fightin’ Texas Aggie • .Net and PHP Developer • UNIX and Windows Sysadmin • Senior Consultant at Improving Enterprises • Contact Me: chris@chrisweldon.net
- 4. Agile, Microsoft, OpenTechnologies, UX Applied Training, Coaching, Mentoring Certified Consulting Rural Sourcing Recruiting Services
- 5. Before We Getto IoC... <?php class Authenticator { private $_repository; public function __construct() { $this->_repository = new DataAccessLayer(); } public function authenticate($username, $password) { $hashedPassword = md5($password); $user = $this->_repository->findByUsernameAndPassword( $username, $hashedPassword); return $user === null; } }
- 6. What are theproblems?
- 7. What are theproblems? • Strongly coupled to DataAccessLayer
- 8. What are theproblems? • Strongly coupled to DataAccessLayer Authenticator authenticate() : bool DataAccessLayer findByUsernameAndPassword : array
- 9. What are theproblems? • Strongly coupled to DataAccessLayer • Authenticator Very inflexible authenticate() : bool DataAccessLayer findByUsernameAndPassword : array
- 10. What are theproblems? • Strongly coupled to DataAccessLayer • Authenticator Very inflexible authenticate() : bool • How to configure DataAccessLayer? DataAccessLayer findByUsernameAndPassword : array
- 11. What are theproblems? • Strongly coupled to DataAccessLayer • Authenticator Very inflexible authenticate() : bool • How to configure DataAccessLayer? • DataAccessLayer Let it read configs? findByUsernameAndPassword : array
- 12. What are theproblems? • Strongly coupled to DataAccessLayer • Authenticator Very inflexible authenticate() : bool • How to configure DataAccessLayer? • DataAccessLayer Let it read configs? findByUsernameAndPassword : array • How to test the Authenticator?
- 13. Let’s solve it • What are our goals? • Decrease coupling • Increase configurability
- 14. <?php interface IUserRepository { function findByUsernameAndPassword($username, $password); } class DataAccessLayer implements IUserRepository { private $_configParams; private $_database; public function __construct(array $configParams) { $this->_configParams = $configParams; $this->_database = Zend_Db::factory('Pdo_Mysql', $this->_configParams); } public function findByUsernameAndPassword($username, $password) { $query = 'SELECT * FROM users WHERE username = ? AND password = ?'; $result = $this->_database->fetchAll($query, $username, $password); return $result; } }
- 15. Our Updated Authenticator <?php classAuthenticator { private $_repository; public function __construct(IUserRepository $repository) { $this->_repository = $repository; } public function authenticate($username, $password) { $hashedPassword = md5($password); $user = $this->_repository->findByUsernameAndPassword( $username, $hashedPassword); return $user === null; } }
- 16. Time to Consume <?php classLoginController { public function login($username, $password) { $configuration = Zend_Registry::get('dbconfig'); $dal = new DataAccessLayer($configuration); $authenticator = new Authenticator($dal); if ($authenticator->authenticate($username, $password)) { // Do something to log the user in. } } }
- 17. Goal Recap • What were our goals? • Decrease coupling • Increase configurability
- 18. Goal Recap • What were our goals? • Decrease coupling • Increase configurability
- 19. Goal Recap • What were our goals? • Decrease coupling • Increase configurability
- 20. What You SawWas IoC • Inversion of Control changes direction of responsibility • Someone else responsible for creating and providing my dependencies • Most commonly applied pattern: Dependency Injection • Follows Dependency Inversion Principle from SOLID • Culture War: IoC vs. DI vs. Naming vs. Principles vs. Ideology
- 21. Dependency Inversion • “High-level modules should not depend upon low level modules. They should depend upon abstractions. • “Abstractions should not depend upon details. Details should depend upon abstractions.” Robert Martin
- 22.
- 23. Let’s Draw Authenticator authenticate() : bool DataAccessLayer findByUsernameAndPassword : array
- 24. Let’s Draw Authenticator authenticate() : bool DataAccessLayer findByUsernameAndPassword : array
- 25. Let’s Draw Authenticator authenticate() : bool Authenticator authenticate() : bool IUserRepository findByUsernameAndPassword : array DataAccessLayer findByUsernameAndPassword : array DataAccessLayer findByUsernameAndPassword : array
- 26. Benefit: Flexibility <?php class WebServiceUserRepositoryimplements IUserRepository { public function findByUsernameAndPassword($username, $password) { // Fetch our user through JSON or SOAP } } class OAuthRepository implements IUserRepository { public function findByUsernameAndPassword($username, $password) { // Connect to your favorite OAuth provider } }
- 27. Benefit: Testable <?php class WhenAuthenticatingextends PHPUnit_Framework_TestCase { public function testGivenInvalidUsernameAndPasswordShouldReturnFalse() { $stub = $this->getMock('IUserRepository'); $stub->expects($this->any()) ->method('findByUsernameAndPassword') ->will($this->returnValue(null)); $authenticator = new Authenticator($stub); $this->assertFalse($authenticator->authenticate('user', 'pass')); } }
- 28. Dependency Injection • Now we can inject our dependencies to our consumer classes • Still requires some other class to be tightly coupled to both of those • Need a container that can help abstract the relationship between the interface and implementation
- 29. <?php class UserRepositoryContainer { /** @return IUserRepository **/ public function getRepository() { $container = new DataAccessLayer(array( 'dsn' => 'mysql://localhost/database', 'username' => 'user', 'password' => 'pass' )); return $container; } } class LoginController { public function login($username, $password) { $container = new UserRepositoryContainer(); $repository = $container->getRepository(); $authenticator = new Authenticator($repository); // ... } }
- 30. Container Woes • No uniform interface by which to access services • Still tightly coupled with dependencies • Configurability of the container difficult • How to auto-inject dependency for configured consumer classes?
- 31. Symfony Dependency Injection Container • Two Ways to Setup and Use sfServiceContainer • Create subclass • Manual registration via code or config
- 32. sfServiceContainer Subclass <?php class UserRepositoryContainerextends sfServiceContainer { protected function getUserRepositoryService() { $container = new DataAccessLayer($this['repository.config']); return $container; } }
- 33. Consuming the Container <?php classLoginController { public function login($username, $password) { $configuration = Zend_Registry::get('dbconfig'); $container = new UserRepositoryContainer(array( 'repository.config' => $configuration )); $repository = $container->userRepository; $authenticator = new Authenticator($repository); if ($authenticator->authenticate($username, $password)) { // Do something to log the user in. } } }
- 34. That’s Pretty Nice • Configurability a lot easier • Uniform interface for accessing services • How does this scale when there are lots of dependencies? • Aren’t we still coupling the container to the implementation at compile time?
- 35. The Builder • Provides a uniform way of describing services, without custom containers • For each service description, we have the flexibility to configure an object: • At instantiation (Constructor Injection) • Post-instantiation (Setter/Method Injection)
- 36. How to Describea Service • Code-based or Config-based • Code-based allows for run-time changing of injection parameters • Config-based provides a way to change parameters between environments with no code changes • Not mutually exclusive
- 37. Code-Based Description <?php // Imaginethis is a bootstrap file. $configuration = Zend_Registry::get('dbconfig'); $builder = new sfServiceContainerBuilder(); $builder->register('user_repository', 'DataAccessLayer') ->addArgument($configuration) // OR ->addArgument('%repository.config%') from earlier ->setShared(false); $builder->register('authenticator', 'Authenticator') ->addArgument(new sfServiceReference('user_repository')); Zend_Registry::set('di_container', $builder);
- 38. Config-Based Description <?xml version="1.0"?> <container xmlns="http://symfony-project.org/2.0/container"> <parameters> <parameter key="user_repository.dsn">mysql://localhost/database</parameter> <parameter key="user_repository.username">username</parameter> <parameter key="user_repository.password">password</parameter> </parameters> <services> <service id="user_repository" class="DataAccessLayer" shared="false"> <argument type="collection"> <argument key="dsn">%user_repository.dsn%</argument> <argument key="username">%user_repository.username%</argument> <argument key="password">%user_repository.password%</argument> </argument> </service> <service id="authenticator" class="Authenticator"> <argument type="service" id="user_repository" /> </service> </services> </container>
- 39. Loading the Config <?php //Imagine this is a bootstrap file. $builder = new sfServiceContainerBuilder(); $loader = new sfServiceContainerLoaderFileXml($builder); $loader->load('/pathTo/services.xml'); Zend_Registry::set('di_container', $builder);
- 40. Using the Container <?php classLoginController { public function login($username, $password) { $container = Zend_Registry::get('di_container'); $authenticator = $container->authenticator; if ($authenticator->authenticate($username, $password)) { // Do something to log the user in. } } }
- 41. High Level Picture DataAccessLayer findByUsernameAndPassword : array IUserRepository findByUsernameAndPassword : array sfServiceContainerBuilder getService : object setService : void hasService : bool Authenticator authenticate() : bool IAuthenticator authenticate() : bool sfServiceContainerInterface getService : object LoginController setService : void login() : void hasService : bool
- 42. When to Usea DI Container
- 43. When to Usea DI Container • Not for model objects (e.g. Orders, Documents, etc.)
- 44. When to Usea DI Container • Not for model objects (e.g. Orders, Documents, etc.) • Great for resource requirements (e.g. repositories, loggers, etc.)
- 45. When to Usea DI Container • Not for model objects (e.g. Orders, Documents, etc.) • Great for resource requirements (e.g. repositories, loggers, etc.) • Really great for plugin-type architecture
- 46. When to Usea DI Container • Not for model objects (e.g. Orders, Documents, etc.) • Great for resource requirements (e.g. repositories, loggers, etc.) • Really great for plugin-type architecture • But not necessary to use Dependency Injection!
- 47.
- 48. Other Considerations • Learning curve
- 49. Other Considerations • Learning curve • Tracking dependencies
- 50. Other Considerations • Learning curve • Tracking dependencies • Dependency changes
- 51. Other Considerations • Learning curve • Tracking dependencies • Dependency changes • Setter/method vs. constructor injection
- 52. Service Lifetimes • setShared() allows you to specify context persistence • If shared, acts like a singleton • Useful if construction is expensive or state persistence required
- 53.
- 54. Thank You! http://bit.ly/rf1pxR git://github.com/neraath/ioc-php-talk.git