Request Lifecycle

This is the sequence of events that happens every time the application receives an HTTP request.

 

Routing:

• The process begins with the Routing module.
• The Routing module uses URL rewriting to map the incoming request's URL to a specific route defined in the application's route table (usually in RouteConfig.cs).
• A route essentially defines a pattern for URLs and specifies which controller and action method should handle requests that match that pattern.
• For example, a route might define that a request to "/Products/Details/5" should be handled by the Details action method of the ProductsController, with the "5" being an ID parameter.

 

Controller Instantiation:

• Once a matching route is found, the MvcHandler is invoked.
• The MvcHandler uses a ControllerFactory to create an instance of the appropriate controller class.
• The ControllerFactory is responsible for actually creating the controller object. This design allows for flexibility, such as using dependency injection to create controllers.
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Action Invocation:

• The controller receives the request.
• The ActionInvoker then determines which action method within the controller should be executed, based on the route data and possibly other factors like HTTP verb (GET, POST, etc.).
• Action Invokers handle the process of selecting the correct method to call.

 

Model Binding:

• Before the action method is executed, the MVC framework performs model binding.
• Model binding maps data from the HTTP request (such as form data, query string parameters, or route data) to the parameters of the action method.
• For instance, if a user submits a form with fields "Name" and "Email", model binding will automatically try to map those values to the Name and Email parameters of the controller's action method.

 

Action Execution:

• The selected action method is executed.
• The action method contains the core logic for handling the request.
• It interacts with the Model to retrieve or update data, and it determines what data to pass to the View.
• This is where you write the code that processes the user's request, interacts with your data, and prepares the application's response.

 

View Engine:

• The controller action returns an Action Result.
• If the result is a View, the View Engine is involved.
• The View Engine locates and processes the appropriate View file (e.g., a .cshtml file in ASP.NET MVC).
• The View is rendered, combining the data from the Model with HTML markup to generate the HTML that will be sent to the client.
• The View Engine takes the data you pass from the controller and merges it with your View template to produce the final HTML.

 

• Response:
• Finally, the MVC framework sends the generated HTML (or other content, such as JSON or a file) back to the user's browser as the HTTP response.
• The server sends this response back to the client that made the request.