For many years, software engineers have successfully applied the UML® to model-based software engineering. There have been several attempts to introduce the UML and the underlying object-oriented methods to systems engineering in order to unify the overall development process. However, many systems engineers continue to use classical structured analysis techniques and artifacts to define system requirements and designs. One reason for this could be that systems engineering is mostly driven by functional requirements. Speaking in terms of system functionality is still considered the most natural way of expressing a design by most of the domain experts involved in the early phases of system development (electrical engineers, mechanical engineers, test engineers, marketing, and, of course, customers). Given this, the only way to unify the overall development process is to extend the UML with regard to function-driven systems engineering and to define a process that enables a seamless transfer of respective artifacts to UML based software engineering. For this purpose, the OMG (Object Management Group) formed the SysML (Systems Modeling Language) consortium.

The following sections describe a SysML-based process that systems engineers can use to capture requirements and specify architecture. The approach uses model execution as a means for requirements verification and validation.