Separation of concerns - DPC 12

Transcript

1. Separation of Concerns
2. Separation of concerns About Joshua  Joshua Thijssen, NoxLogic / Techademy  Freelance Consultant, Developer, Trainer  Development in PHP, Python, Perl, C, Java  jthijssen@noxlogic.nl  @jaytaph
3. Separation of concerns About Stephan  Stephan Hochdörfer, bitExpert AG  Department Manager Research Labs  enjoying PHP since 1999  S.Hochdoerfer@bitExpert.de  @shochdoerfer
4. Separation of concerns It is what I sometimes have called the separation of concerns, which [...] is yet the only available technique for effective ordering of one's thoughts. Edsger W. Dijkstra, "On the role of scientific thought" (1974)
5. Separation of concerns SoC […] is the process of breaking a computer program into distinct features that overlap in functionality as little as possible. http://en.wikipedia.org/wiki/Separation_of_concerns
6. Separation of concerns It`s all about focusing!
7. Separation of concerns One step a time. Focus on the details!
8. Separation of concerns <?php $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access_token?..."); $feed = file_get_contents("https://graph.facebook.com/ident/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } } $feed = file_get_contents("http://search.twitter.com/search.json?q=from:ident"); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); } foreach($items as $item) { echo $item['message']; }
9. Separation of concerns <?php $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access_token?..."); $feed = file_get_contents("https://graph.facebook.com/ident/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } } $feed = file_get_contents("http://search.twitter.com/search.json?q=from:ident"); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); } foreach($items as $item) { echo $item['message']; }} Controller part!
10. Separation of concerns <?php $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access_token?..."); $feed = file_get_contents("https://graph.facebook.com/ident/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } } $feed = file_get_contents("http://search.twitter.com/search.json?q=from:ident"); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); } foreach($items as $item) { echo $item['message']; } View part!
11. Separation of concerns Very unstable. Not safe for changes....
12. Separation of concerns „Make everything as simple as possible...“
13. Separation of concerns Establish boundaries
14. Separation of concerns What are the boundaries? Presentation Layer
15. Separation of concerns What are the boundaries? Presentation Layer Business Layer
16. Separation of concerns What are the boundaries? Presentation Layer Business Layer Resource Access Layer
17. Isolate functionality, break it apart! Separation of concerns
18. Separation of concerns <?php namespace Acme\DemoBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template; class DemoController extends Controller { /** * @Route("/", name="_demo") * @Template() */ public function indexAction() { $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access_to..."); $feed = file_get_contents("https://graph.facebook.com/ident/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } }
19. Separation of concerns $feed = file_get_contents("http://search.twitter.com/search.json?..."); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); } return array('items' => $items); } }
20. Focus on one responsibility a time! Separation of concerns
21. Separation of concerns <?php namespace Acme\DemoBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template; class DemoController extends Controller { /** * @Route("/", name="_demo") * @Template() */ public function indexAction() { $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access_to..."); $feed = file_get_contents("https://graph.facebook.com/ident/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } } Facebook connector
22. Separation of concerns $feed = file_get_contents("http://search.twitter.com/search.json?..." ); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); } return array('items' => $items); } } Twitter connector
23. Interfaces as a contract Separation of concerns
24. Separation of concerns <?php interface ConnectorInterface { /** * Will return an array of the latest posts. * return array */ public function getLatestPosts() { } }
25. Separation of concerns <?php class FacebookConnector implements ConnectorInterface { protected $handle; public function __construct($handle) { $this->handle = $handle; } public function getLatestPosts() { $items = array(); $token = file_get_contents("https://graph.facebook.com/oauth/access..."); $feed = file_get_contents("https://graph.facebook.com/. $this->handle."/feed?".$token); $feed = json_decode($feed, true); foreach($feed['data'] as $post) { if('123456789012' === $post['from']['id']) { $items[] = array( 'date' => strtotime($post['created_time']), 'message' => $post['message']); } } return $items; } }
26. Separation of concerns <?php class FacebookConnector implements ConnectorInterface { protected $handle; public function __construct($handle) { $this->handle = $handle; } public function getLatestPosts() { $token = $this->getAccessToken(); return $this->readPosts($token); } protected function getAccessToken() { return file_get_contents("https://graph.facebook.com/oauth/access_?..."); } protected function readPosts($token) { // read the post, filter all relevant and return them... } }
27. Separation of concerns <?php class FacebookConnectorV2 extends FacebookConnector { protected function getAccessToken() { return md5($this->handle); } } Easy to extend, will not influence the behaviour of other methods!
28. Separation of concerns <?php namespace Acme\DemoBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template; class DemoController extends Controller { /** * @Route("/", name="_demo") * @Template() */ public function indexAction() { $items = array(); $fb = $this->get('FbConnector'); $items += $fb->getLatestPosts(); $feed = file_get_contents("http://search.twitter.com/search.json?..."); $feed = json_decode($feed, true); foreach($feed['results'] as $tweet) { $items[] = array( 'date' => strtotime($tweet['created_at']), 'message' => $tweet['text']); }
29. Separation of concerns <?php namespace Acme\DemoBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template; class DemoController extends Controller { /** * @Route("/", name="_demo") * @Template() */ public function indexAction() { $items = array(); $fb = $this->get('FbConnector'); $items += $fb->getLatestPosts(); $twitter = $this->get('TwitterConnector'); $items += $twitter->getLatestPosts(); return array('items' => $items); } }
30. Will improve the testability! Separation of concerns
31. Will reduce tight coupling! Separation of concerns
32. Will increase component reuse! Separation of concerns
33. The value of separation Why should I do it? Separation of concerns
34. The value of separation 1. Getting rid of code duplication Separation of concerns
35. The value of separation 2. Application becomes more stable and easier to understand Separation of concerns
36. The value of separation 3. Single responsibility offers clear extension points Separation of concerns
37. The value of separation 4. Increases the reusability of components Separation of concerns
38. Separation of concerns How to separate the concerns?
39. Separation of concerns How to separate? Horizontal Separation Presentation Layer Business Layer Resource Access Layer
40. Separation of concerns How to separate? Horizontal Separation ./symfony |-app |---cache |---config |---Resources |-src |---Acme |-----DemoBundle |-------Controller |-------Resources |---------config |---------public |-----------css |-----------images |---------views |-----------Demo |-----------Welcome |-------Tests |---------Controller |-web
41. Separation of concerns How to separate? Service Separation Service Interface Layer Business Layer Resource Access Layer
42. Separation of concerns How to separate? Service Separation Frontend / UI Webservers REST API Datastore Solr Search Service
43. Separation of concerns How to separate? Vertical Separation Module A Module B Module C
44. Separation of concerns How to separate? Vertical Separation ./symfony |-app |---cache |---config |---Resources |-src |---Acme |-----AdminBundle |-------Controller |-------Resources |-------Tests |-----ProductsBundle |-------Controller |-------Resources |-------Tests |-----CustomersBundle |-------Controller |-------Resources |-------Tests |-web
45. Separation of concerns How to separate? Vertical Separation Presentation Layer Business Layer Resource Access Layer Presentation Layer Business Layer Resource Access Layer Presentation Layer Business Layer Resource Access Layer
46. Separation of concerns How to separate? Vertical Separation ./symfony |-app |---cache |---config |---Resources |-src |---Acme |-----AdminBundle |-------Controller |-------Resources |-------Tests |-----ProductsBundle |-------Controller |-------Resources |-------Tests |-----CustomersBundle |-------Controller |-------Resources |-------Tests |-web
47. Cross-cutting concerns? How to deal with security or logging aspects? Separation of concerns
48. Separation of concerns How to separate? Aspect Separation Presentation Layer Business Layer Resource Access Layer Aspects
49. Separation of concerns How to separate? Aspect Separation <?php namespace Acme\Products\Aspects; /** * @FLOW3\Aspect */ class LoggingAspect { /** * @FLOW3\Inject * @var \Acme\Logger\LoggerInterface */ protected $logger; /** * @param \TYPO3\FLOW3\AOP\JoinPointInterface $joinPoint * @FLOW3\Before("method(Acme\Products\Model\Product->delete())") */ public function log(\TYPO3\FLOW3\AOP\JoinPointInterface $jp) { $product = $jp->getMethodArgument('product'); $this->logger->info('Removing ' . $product->getName()); } }
50. Separation of concerns Dependency Direction
51. Separation of concerns Dependency Direction "High-level modules should not depend on low-level modules. Both should depend on abstractions." Robert C. Martin
52. Separation of concerns Inverting Concerns Presentation Layer Business Layer Resource Access Layer
53. Separation of concerns Inverting Concerns Presentation Layer Business Layer Resource Access Layer Presentation Layer Business Layer Resource Access Layer UI Component
54. Separation of concerns Inverting Concerns The goal of Dependency Injection is to separate the concerns of obtaining the dependencies from the core concerns of a component.
55. Separation of concerns What are the benefits? Let`s recap....
56. Separation of concerns What are the benefits? 1. Facilitate reusability
57. Separation of concerns What are the benefits? 2. Ensure the maintainability
58. Separation of concerns What are the benefits? 3. Increasing the code quality
59. Separation of concerns What are the benefits? 4. Enables everyone to understand the application
60. Separation of concerns What are the benefits? 5. Allows developers to work on components in isolation
61. Thank you!
62. http://joind.in/6244