1. A method for enabling data sharing between software systems, comprising: managing at least one data-sharing session for each of a plurality of users with a server computer system, each said data-sharing session having a set of software systems associated with said user participating therein, said server computer system maintaining requests for said software systems to be notified of updates to values of sets of requested data items, said set of software systems sharing data item values in said data-sharing session, said server computer system storing said shared data item values, resolving said shared data item values to said requested data items using semantic descriptions provided for said shared data item values and said requested data items, and providing available updates to said shared data item values resolving to said sets of requested data items to said software systems.