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Web Application ArchitecturesModule 5: Middleware
Lecture 8: MVC Implementation in Rails
c© 2011-13 G.L. Heileman Module 5, Lecture 8 1 / 4
Ruby on Rails
In Rails, the following classes support the MVC design pattern:
Model – The ActiveRecord class, described previously, implementsobject-relational mappings (ORM).
View – Views and controllers are actually bundled together in Rails inAction Pack. Dynamic content is generated by templates containingembedded Ruby (ERb) code supported by the ActionView class.
Controller – The ActionController class is the core of a web request inRails. It consists of one or more actions that are executed on requestand then either render a template or redirect to another action. Anaction is defined as a public method on the controller, which willautomatically be made accessible to the web-server through RailsRoutes.
c© 2011-13 G.L. Heileman Module 5, Lecture 8 2 / 4
MVC Interactions in Rails
1 The browser sends a request to the web server.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
4 The model layer collects the requested information and returns it tothe controller.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
4 The model layer collects the requested information and returns it tothe controller.
5 The controller gives the appropriate information to the view,requesting a particular format.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
4 The model layer collects the requested information and returns it tothe controller.
5 The controller gives the appropriate information to the view,requesting a particular format.
6 The view renders the information in that format and gives it back tothe controller.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
4 The model layer collects the requested information and returns it tothe controller.
5 The controller gives the appropriate information to the view,requesting a particular format.
6 The view renders the information in that format and gives it back tothe controller.
7 The controller assembles the total page’s html and gives it to the webserver.
1 The browser sends a request to the web server.2 The web server processes the request, determines which route it
belongs to and dispatches that request to the corresponding controllermethod.
3 The controller asks the model layer for all of the information neededto complete the request.
4 The model layer collects the requested information and returns it tothe controller.
5 The controller gives the appropriate information to the view,requesting a particular format.
6 The view renders the information in that format and gives it back tothe controller.
7 The controller assembles the total page’s html and gives it to the webserver.
8 The web server returns the page to the browser.
Browser
Web Server
1 http://localhost:3000/posts(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
1
2
http://localhost:3000/posts
PostsController::index
resources :posts
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all
resources :posts
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all4 Post array
resources :posts
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model View
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all 5 @posts4 Post array
resources :posts
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model View
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all 5 @posts4 Post array 6 index.html.erb
resources :posts
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model View
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all 5 @posts4 Post array 6 index.html.erb
resources :posts7 application.html.erb
+ index.html
(GET request)
Browser
Web Server
Routes
Dispatcher
Controller
Model View
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all 5 @posts4 Post array
8 text/html
6 index.html.erb
resources :posts7 application.html.erb
+ index.html
(response)(GET request)
c© 2011-13 G.L. Heileman Module 5, Lecture 8 3 / 4
MVC Interactions in Rails
Browser
Web Server
Routes
Dispatcher
Controller
Model View
1
2
http://localhost:3000/posts
PostsController::index
3 @posts = Post.all 5 @posts4 Post array
8 text/html
6 index.html.erb
resources :posts7 application.html.erb
+ index.html
(response)(GET request)
c© 2011-13 G.L. Heileman Module 5, Lecture 8 4 / 4
