rollback

In case error occured when executing a command but the command was already applied locally it has to be rolled back.

The RollbackController takes care of this. Everytime a Command is executed locally bevore/without the managing servers command, a copy of the target object is made. In case the managing encounters an exception when executing the command this old object will be restored. In case all goes well the client will receive the receivedCommand wich is a special command to say that the execution of another command finished successuflly.