This is strictly just a UI concept at this point, but it's a very simple Silverlight implementation of drawing some shapes on the screen, connecting them with lines, then clicking and dragging the shapes around while maintaining the line connections. 

Source Code: nodeconnect2.zip [552 kb]

Example App: http://kindohm.com/sl/NodeConnect/TestPage.html

It's hard to explain the highlights with only small code snippets (I don't want to paste the entire source code into this post), but here is a shot at some of the key features...

The nodes/shapes were implemented as Silverlight user controls. Clicking and dragging was simply handled on the user control's MouseMove event in combination with up/down state of the left mouse button.  The MoveNode method does the dirty work:

Point lastPoint;

//declared as a XAML element...
TranslateTransform translation;

void MoveNode(Point currentPosition)
{
  double deltaX = currentPosition.X - this.lastPoint.X;
  double deltaY = currentPosition.Y - this.lastPoint.Y;
  this.translation.X = this.translation.X + deltaX;
  this.translation.Y = this.translation.Y + deltaY;  
  this.lastPoint = position;
}

As for drawing and re-drawing the lines, I created a Connection class that is just a data structure that describes a Line and where it starts from. To update the lines when a shape is moved, I just iterate through a Dictionary that stores a Connection for each control that the moved control is connected to. The Dictionary is maintained for all controls so that each control is aware of everything it is connected to:

public class NodeControl
{

...

  void MoveConnections()
  {
    foreach (NodeControl key in this.connections.Keys)
    {
      Connection connection = this.connections[key];
      Point newPosition = 
        NodeControl.GetCoordinatesForControl(this);
      Line line = connection.Line;
  
      //IsPrimary determines if this 
      //control holds the start or end
      //of the line
      if (connection.IsPrimary)
      {
        line.X1 = newPosition.X;
        line.Y1 = newPosition.Y;
      }
      else
      {
        line.X2 = newPosition.X;
        line.Y2 = newPosition.Y;
      }                
    }
  }

...

}

Oh the data visualization possibilities...

Enjoy.