The Essential Diagram web server control is built using a Subject-Observer design
pattern that makes the product reliable, highly extensible and easy to customize.
Essential Diagram stores graphical objects in a node graph and renders those objects
onto the display medium. The software supports both vector and raster graphics on
the drawing surface. A powerful object model that is shared between the Windows
and Web versions of the product, a hierarchical node structure, a wide selection
of drawing shapes, styles and properties inheritance, and an extensible command
model make Essential Diagram an ideal diagramming platform for building highly specialized