A message driven processor operates as middleware between clients and back-end hosts or servers in a large client-server system to reduce the number of concurrent sessions required to be supported by the network and to allow a common client user interface to divergent back-end systems. High level requests from a client in support of a business function are translated into workflows which may involve multiple requests to back-end servers by the message driven processor. Information resulting from workflows and information retrieved from back-end servers may be integrated into a single reply message to the requesting client.