To describe the hardware elements and model the network, we use three different views to model
the structure of the system: the object construction and the software structure view focus on the
software architecture of the system, while the system architecture view gives out an sketch of the
system hardware and the communication method among system components. To describe the
time constraints, UML supplies sequence diagrams and collaboration diagrams, which are able to
specify the real-time feature of the system by way of marking time constraints aside by the names
of message and object.