Translation Servers: Gateways Between Stateless and Stateful Information Systems

Public information systems offering access to the network community can be divided into two groups: those with stateful protocols and those with stateless protocols. Evolving client-server protocols like the Hypertext Transfer Protocol (HTTP) of the World-Wide Web (W3) are stateless. In this case the reaction of the information server depends on the request only. To access the server, special client programs (browsers) are required. Such browsers are comfortable tools for users, however they cannot access stateful servers directly. For this purpose either additional, stateful client programs or additional servers are required. This paper introduces the concept of Translation Servers, generic gateways to provide uniform and stateless access to stateful information servers for stateless browsers, without restructuring or duplicating the data. To communicate with the stateful information server, the Translation Server accesses the same user interface that has been designed for human use. Some of the problems discussed in this paper hold also for other inherently stateful applications offered on stateless information servers, like electronic shopping malls or data modification.