The instance of the object model illustrated in An Instance of the Company Object Model can be represented in several different ways according to your requirements. For example, you could display it as:

These two types of representation are illustrated below.

For each type of representation of an object-model instance handled by an application component—in our example, a tree and a matrix—you must define a view type. Each view ensures that each time a server object is modified, created, or removed following a request issued from an application component, other application components connected to the object model will be notified of this update. Application components can be graphical applications or any other type of application.

According to the foregoing requirements, two view types must be defined to represent the Company object model:

View types and the object model interact through a view server (see its definition in “View Server”). Figure 7.5 illustrates the Company view server, which is made up of an instance of our object model and a group of views.