Jack @ ASP.NET

Key characteristics of VIEW
? The view is a visual element, such as a window, page, user control, or data template. The view defines the controls contained in the view and their visual layout and styling.
? The view references the view model through its DataContext property. The controls in the view are data bound to the properties and commands exposed by the view model.
? The view may customize the data binding behavior between the view and the view model. For example, the view may use value converters to format the data to be displayed in the UI, or it may use validation rules to provide additional input data validation to the user.
? The view defines and handles UI visual behavior, such as animations or transitions that may be triggered from a state change in the view model or via the user’s interaction with the UI.
? The view’s code-behind may define UI logic to implement visual behavior that is difficult to express in XAML or that requires direct references to the specific UI controls defined in the view.

Key characteristics of’ ‘VIEWMODEL’
? The view model is a non-visual class and does not derive from any WPF or Silverlight base class. It encapsulates the presentation logic required to support a use case or user task in the application. The view model is testable independently of the view and the model.
? The view model typically does not directly reference the view. It implements properties and commands to which the view can data bind. It notifies the view of any state changes via change notification events via the INotifyPropertyChanged and INotifyCollectionChanged interfaces.
? The view model coordinates the view’s interaction with the model. It may convert or manipulate data so that it can be easily consumed by the view and may implement additional properties that may not be present on the model. It may also implement data validation via the IDataErrorInfo or INotifyDataErrorInfo interfaces.
? The view model may define logical states that the view can represent visually to the user.

Key characteristics of ‘MODEL’
? Model classes are non-visual classes that encapsulate the application’s data and business logic. They are responsible for managing the application’s data and for ensuring its consistency and validity by encapsulating the required business rules and data validation logic.
? The model classes do not directly reference the view or view model classes and have no dependency on how they are implemented.
? The model classes typically provide property and collection change notification events through the INotifyPropertyChanged and INotifyCollectionChanged interfaces. This allows them to be easily data bound in the view. Model classes that represent collections of objects typically derive from the ObservableCollection<T> class.
? The model classes typically provide data validation and error reporting through either the IDataErrorInfo or INotifyDataErrorInfo interfaces.
? The model classes are typically used in conjunction with a service or repository that encapsulates data access and caching.

1. Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client’s browser.

2. What type of code (server or client) is found in a Code-Behind class?
Server-side code. Since code-behind is executed on the server. However, during the code-behind’s execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.

3. Should user input data validation occur server-side or client-side?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.

4. What is the difference between Server.Transfer and Response.Redirect?
Why would I choose one over the other? Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client’s browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients url history list or current url. Response.Redirect is used to redirect the user’s browser to another page or site. This performas a trip back to the client where the client’s browser is redirected to the new page. The user’s browser history list is updated to reflect the new address.

5. What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.

6. What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.

7. Whats an assembly?
Assemblies are the building blocks of the .NET framework.

8. Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.

9. Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

10. Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.