Basics of system modelling in UML

Everyone knows what engineering is. All that's left is to define systems, and I'm not fool enough to do that.

Some engineering artifacts are most easily analysed, described, or designed as an assembly of simpler parts. Artifacts of this kind are called systems. Some systems have the property that flowing through them are streams of some 'working fluid' (which may be matter, energy, or information), in such a way that the 'working fluid' passes in turn through many parts of the system, which is in consequence termed a sequential (or flow) system. Examples are a chemical plant, an electrical power distribution network, a digital computer, a sewer system. Systems which do not have this property are termed associative systems of which examples are a motor car, an aircraft, or a bridge - - it is with (sequential) systems that the theory of system design has primarily been developed.

In the past the man has been first; in the future the system must be first. This in no sense, however, implies that great men are not needed. On the contrary, the first object of any good system must be that of developing first-class men