The Express Property Management business logic layer will encapsulates all knowledge about business process of application. It will not have any knowledge of the database all database activity is hidden in the data access layer. The business logic layer enlists the data access layer to do all the database related work. Meanwhile, presentation layer of the EPM application will use the business logic layer directly.

The business rules layer contains not only rules that determine what to do with data, but also how and when to do it. For an application to become scalable, it is often necessary to split the business rules layer into two separate layers: the client-side business logic, which we will call Workflow layer and the server-side business logic called business logic layer. Although we describe these layers as client and server side, the actual physical implementations can vary. Generally, workflow rules govern user input and other processes on the client, while business logic controls the manipulation and flow of data on the server. As the design strategy in EPM, we will move workflow layer on to the client side. Which means all the client side rules and validations will consist of workflow layer.