A system and method featuring a collection of model objects which hold data to be shared, and supporting interfaces to read and write the data, to create and destroy collaboration relationships and to attach "view objects" containing application code which will be automatically notified of value changes. Each user environment is provided with a model object control entity, referred to herein as a Collaboration Manager, which creates model objects, executes transactions, and creates association objects related to the collaboration. A concurrency control mechanism records the reads and updates of the data and of collaboration relationships within a single transaction site and guarantees that they are applied atomically and consistently to both the local and to all remote replica objects of the collaboration.