8.7 System Design

System Design with UML

• UML is a modern technique of system design and is used as documentation for all systems proposed in project tenders submitted to the British government.
• The Unified Modeling Language (UML) is a language for specifying, visualizing, constructing, and documenting the features of systems.
• UML represents a collection of best engineering practices that have proven successful in the modeling of large and complex systems.
• UML uses graphical notations to express the design of system projects and helps project teams communicate, explore potential designs, and validate the architectural design of systems.
• The primary goals of UML were to provide users with a ready-to-use, expressive visual modeling language, provide extensibility and specialization mechanisms, be independent of particular programming languages and development processes, provide a formal basis for understanding the modeling language, support higher-level development concepts, and integrate best practices.
• UML diagrams are designed to let developers and customers view a system from a different perspective and in varying degrees of abstraction.
• There are six diagrams to be drawn for a UML conformant documentation, but in this module, only the interaction and the use case diagrams are needed.
• The UML use case diagrams display the relationship among actors (users) and use cases.
• Interaction diagrams consist of sequence diagrams and collaboration diagrams, with primary focus on use case and sequential interaction diagrams in this course.
• After the diagrams are drawn, the task to be executed is implemented using a combination of hardware and software that the computer has to do.
• Hardware testing should be done on each sub-system basis, using simple programs designed to fully test out the hardware, and modern instruments like Logic Analyzers and In-Circuit Emulators can be used.
• After the software code for each subsystem has been written and converted into machine code, it must be tested to verify that it functions correctly, and this requires a 'protected' environment to test the software, with the aim of minimizing the number of untested software codes which have to be checked during system integration.