The big picture

A picture or diagram can represent a thousand words. For that reason alone, visual modelling has become a popular way of describing complex systems. Historically, visual modelling has been used more often in a software design context. Now, as systems grow in complexity, there is an increasing need for designers to model whole systems in a standardised manner. Whilst the unified modelling language (UML) was developed largely with the software design community in mind, the constructs employed in UML were commonly used to express non software concepts. Hence, in 2003, the SysML specification project was founded to develop a domain specific modelling language for systems engineering applications. The resulting specification, adopted by the Object Management Group in July 2006, supports the specification, analysis, design, verification and validation of a broad range of systems and systems of systems. Artisan’s chief consultant Matthew Hause, whose background is in control systems, explains the ethos behind SysML. “When you do something like functional decomposition, you don’t have entities that map to what happens in the real world. You used to have to break your system out into its various viewpoints and then there was no way to connect them. What SysML and UML both allow – since they have the ‘class’ and the ‘block’ – is the creation of an entity that has information about itself, a set of functions that it can do, and a set of relationships with other elements. If what you are trying to do is to mirror what’s happening in the real world, you have a better chance.” Among the many characteristics that SysML and UML also share is that they both cater for system architectures with interfaces.