The executed commands may be stored in a stack to provide undo and redo functionality. These diagrams show the structure and behavior of a command stack.
Proper logs are essential for long-term system administration. A good logging module should be extensible, configurable and easy to use. This example model may be a good starting point for your solution. It allows you to dynamically change the outputs for the logs and log to multiple targets at once.
Linked list and doubly linked list data structures depicted in UML diagrams.
Model of user module including rights, roles and user access logging.