title: How to update model and view model in MVVM pattern?
body: <p>I am struggling to implement MVVM pattern in my current project.</p>
  
  <p>"ClassA" continuously gets required data from a remote device and stores this data inside it's fields. It is a model, I guess. ClassA updates required information via Update method.</p>
  
  <p>"ClassB" continuously gets the data from "ClassA" and stores it in corresponding properties. Looks like it is a view model.</p>
  
  <p>View is a simple MainWindow.xaml with a DataGrid inside.</p>
  
  <p>I have the following questions: </p>
  
  <p>1) How do I update ViewModel?
  Should ClassB have an Update method, which accepts an instance of ClassA and updates corresponding fields?</p>
  
  <p>2) Where do I store an instance of ClassA?
  Should ClassA be a field of ClassB? If it should, then how do I update Model? 
  I thought of something like the following:</p>
  
  <pre><code>public void UpdateB()
  {
      ClassA.UpdateA();
      this.FieldOne = ClassA.FieldOne;
      this.FieldTwo = ClassA.FieldTwo;
  }
  </code></pre>
  
  <p>4) Does model have it's update method at all or model just stores the data?</p>
  
  <p>3) What do I do inside MainWindow.cs, aside from windows initialization? Do I update view model (ClassB) there?</p>