Abstract: Method and apparatus for maintaining currency in interrelated data which is referred to but not varied by users in a multi-user system which is on-line for 24 hours a day. Reference is had to the data through a data indexing construct available to each user. Currency is maintained by adding updated elements of the data when required by changed external conditions and storing the updated elements in the multi-user system concurrently with the previous version. A new indexing construct is built for the updated data version and users are switched to the construct when access to prior data elements is no longer required. Since only a single variable relating to the indexing construct must be changed in order to switch a user, an atomic operation is utilized to perform the switching.

Abstract: A method for providing synchronous message transfer is provided in an asynchronous operating environment in which conversational status can be established between communicating endpoints. The operating environment includes a transaction processing system having a plurality of terminals, a data communication component (DCC), and a transaction processor (XP) which exchanges message data with DCC for transmission to selected terminals. The method steps comprise ascertaining at the DCC whether a transaction initiated by a message is synchronous or asynchronous; passing the ascertained transaction from the DCC to the XP for generating a response; and processing the responses to synchronous transactions in progress, while retaining the responses to asynchronous transactions until the synchronous responses are completed.