View Model and View Model in Sivlerlight 5

Question

Hi all What is view model and view model ? please dont want links I need definition with proper understanding.

Sanjeeb Lenka · Answer

hi The Model The model is what I like to refer to as the domain object. The model represents the actual data and/or information we are dealing with. An example of a model might be a contact (containing name phone number address etc.) or the characteristics of a live streaming publishing point. The key to remember with the model is that it holds the information but not behaviors or services that manipulate the information. It is not responsible for formatting text to look pretty on the screen or fetching a list of items from a remote server (in fact in that list each item would most likely be a model of its own). Business logic is typically kept separate from the model and encapsulated in other classes that act on the model. This is not always true: for example some models may contain validation. The View The view is what most of us are familiar with and the only thing the end user really interacts with. It is the presentation of the data. The view takes certain liberties to make this data more presentable. For example a date might be stored on the model as number of seconds since midnight on January 1 1970 (Unix Time). To the end user however it is presented with the month name date and year in their local time zone. A view can also have behaviors associated with it such as accepting user input. The view manages input (key presses mouse movements touch gestures etc.) which ultimately manipulates properties of the model. In MVVM the view is active. As opposed to a passive view which has no knowledge of the model and is completely manipulated by a controller/presenter the view in MVVM contains behaviors events and data-bindings that ultimately require knowledge of the underlying model and viewmodel. While these events and behaviors might be mapped to properties method calls and commands the view is still responsible for handling its own events and does not turn this completely over to the viewmodel. One thing to remember about the view is that it is not responsible for maintaining its state. Instead it will synchronize this with the viewmodel. The View Model The viewmodel is a key piece of the triad because it introduces Presentation Separation  or the concept of keeping the nuances of the view separate from the model. Instead of making the model aware of the user's view of a date so that it converts the date to the display format the model simply holds the data the view simply holds the formatted date and the controller acts as the liaison between the two. The controller might take input from the view and place it on the model or it might interact with a service to retrieve the model then translate properties and place it on the view. The viewmodel also exposes methods commands and other points that help maintain the state of the view manipulate the model as the result of actions on the view and trigger events in the view itself. These are the details what i copy paste from this link. you better to go through this link to get example with detail description http://www.codeproject.com/Articles/100175/Model-View-ViewModel-MVVM-Explained

View, Model, and View Model in Sivlerlight 5