A three tier financial transaction system having a local data memory is disclosed. The three tier system includes a client interface, an application service, a host interface, and a local data memory. The client interface communicates data messages between a client program and the financial transaction system. The client interface converts client requests to a format compatible with the application service so the application service may process client requests from client programs. At the initiation of a logical session with a client program, the application service refreshes data for the customer associated with the client program using data obtained from a back end processing system through the host interface. The data in the local data memory is then used by the application service for processing client requests during the logical session. Response data generated by the application service is provided to the client interface for presentation to the client program. Communication between the client program and the client interface is preferably performed over an open communication network. The local data memory permits the processing of the client service request to be decoupled from the updating of the back end processing system to improve response times for client request processing.