Figure 7-3. Architecture of the example OMS
As shown in Figure 7-3, the OMS is divided into three distinct tiers. Each tier is
divided into layers with distinct roles.
The presentation tier is primarily responsible for processing the incoming request and
preparing the HTML-based view to be rendered on the browser. It is also responsible for
invoking the business logic. The data returned by the business tier is then used to pro-
duce the response for the client.