1. The object is initially passive, and is stored in the object store as an instance of the class OutputObjectState .

  2. When required by an application, the object is automatically activated by reading it from the store using a read_committed operation and is then converted from an InputObjectState instance into a fully-fledged object by the restore_state operation of the object.

  3. When the application has finished with the object, it is deactivated by converting it back into an OutputObjectState instance using the save_state operation, and is then stored back into the object store as a shadow copy using write_uncommitted . This shadow copy can be committed, overwriting the previous version, using the commit_state operation. The existence of shadow copies is normally hidden from the programmer by the transaction system. Object deactivation normally only occurs when the top-level transaction within which the object was activated commits