The objective of the model was to define the frame work for the MMI and then supply the actual MMI as static instance data that defines what windows etc. A core part that provides a complete abstract model of a subset of the overall behaviour that is truly common throughout the MMI, for example the rule for determining if a window can be iconised, this core is relatively comprehensible as few ifs and buts exist. Added to this model are a hierarchy of subtypes for the various windows and activities, and these contain all the special to type rules in a non abstract manner. An event passing mechanism and various types of object instance storage so that OOA objects can be implemented in a very direct manner Database Replication Database replication and reconciliation is provided so that standby servers remain in step with current ones, and that workstation copies of server data is maintained. This ensures that servers are consistent before any further action occurs Asynchronous replication of data from servers to workstation computers, this provides the workstations with faster data access, and a standalone capability.
Servers can proceed with further actions before the replication has completed.
A secure multicast transmission protocol that allows multicast, as opposed to point to point, communications to be used to perform the asynchronous updates. This feature is included as an optimisation for the servers.