The architecture of the Branch Transformation Toolkit application solution is based on a logical three-tier model: back-end enterprise tier, application server tier, and client tier.
Within the application server tier, the toolkit has two separate layers. The application presentation layer is responsible for receiving requests from the client and passing that request on to the application logic layer. It also passes the response back to the client. The application logic layer is responsible for performing the request as a process and passing the response back to the application presentation layer. The individual components within the layer are discussed later in this document.
For the most part, the application presentation layer resides in a Web container in WebSphere(R) Application Server while the application logic layer resides in a EJB container. The services are the exception because they can reside anywhere.
The design and portability of the toolkit (resulting from being Java(TM) code) allow the middle-tier servers to exist at either the branch level (one server per branch), the regional level (one server per group of branches), or even a centralized level (a single server for the entire financial institution). The design provides flexibility to achieve the right balance between the number of servers and the network bandwidth without affecting any application logic. Besides the application server, there may be a "technical server" responsible for providing common services (such as disks or printers) to the client workstations. If the application presentation layer and the application logic layer are on the same architectural level, they can physically be on the same machine.