The book club's LitCrit application works on a stand-alone basis. That is, it runs as a Microsoft Exchange Server public folder application that uses Microsoft Outlook as its front end.
The Outlook client is the only element on the user-services tier. Designing the Outlook Form describes the LitCrit Outlook form the Fitch & Mather book club created using the forms design capabilities of Microsoft Outlook.
This stand-alone Outlook application has no business-services tier. In other words, this is a two-tier application, also known as a client/server application. This does not imply that this type of application, featuring an Outlook client on the user-services tier and Exchange directory and information stores on the data-services tier, cannot use business-service COM components. Business Logic in the Outlook Form describes how the enhanced CML/LitCrit Outlook application makes calls to COM components that reside on the business-services tier.
When you post a critique, the information you enter on the LitCrit form is stored in the Exchange public information store and the critique is posted to the LitCrit public folder. How LitCrit Uses Microsoft Exchange describes how the stand-alone LitCrit Outlook application uses the Exchange directory and information store.