Abstract: A method provides access to a data entity having a basis version and the creation of derived versions. The method includes a creating procedure for creating a derived version, by carrying out one or more operations on the basis version, storing them, and accepting them. The method further includes a providing procedure for providing access to the derived version through first addresses mapped to second addresses of the basis version and of the accepted one or more operations, by reconstructing the derived version based on the basis version and the accepted one or more operations.

Abstract: The method controls processing units (10) in a distributed computer system. At least one stream (4) of messages (2) is sent by a client unit (14) to each of the processing units (10). Each message (2) includes an identifier, member of an ordered group. The messages (2) are sent in sequence of their identifier. A controlling unit (12) sends a request (6) for performing an action to the processing units (10). The request (6) includes a trigger, member of the ordered group. If the identifier of a received message (2) is equal to or larger than the trigger, the processing unit (10) triggers the action. The method also relates to a system for controlling processing units (10), to a processing unit (10), and to a controlling unit (12).

Abstract: A method provides access to a data entity having a basis version and the creation of derived versions. The method includes a creating procedure for creating a derived version, by carrying out one or more operations on the basis version, storing them, and accepting them. The method further includes a providing procedure for providing access to the derived version through first addresses mapped to second addresses of the basis version and of the accepted one or more operations, by reconstructing the derived version based on the basis version and the accepted one or more operations.