The advantage of grounding SysML semantics in a declarative approach is that well-known techniques of mathematical logic can then be used to make formal deductions based on the assertions made in a model, in order to prove things that are true or not about the system or domain that is being modeled. Declarative semantics contrast with the operational semantics which specify how a model executes, such that the execution results are evaluated to determine how the system will behave. It is expected that the full semantics for SysML v2 will include both declarative and operational components.
As an example of how the semantics of SysML v2 could be built up from a declarative base, consider the case of the semantics of control nodes used in activity diagrams. Currently (in UML and, so, SysML v1), each type of control node such as a fork node, join node, decision node, or merge node is defined with its own unique semantics. In SysML v2, the general concept of a control node might be specified along with its base semantics. The specific semantics for fork, join, decision and merge nodes could then be specified in the core model library, specializing the base control node semantics. The language formalism would include rules for how this could be done in an unambiguous, rigorous way. A formal mathematically-based language does not have to be difficult to use. The usability of the language will be emphasized using graphical, textual and tabular notations appropriate for practicing system engineers.
Replaced/Superseded by document(s)
The Object Management Group (OMG) is a software consortium with an international membership of vendors, developers, and end users. Established in 1989, its mission is to help computer users solve enterprise integration problems by supplying open, vendor-neutral portability, interoperability and reusability specifications based on Model Driven Architecture (MDA).
MDA defines an approach to IT system specification that separates the specification of system functionality from the specification of the implementation of that functionality on a specific technology platform, and provides a set of guidelines for structuring specifications expressed as models. OMG has published many widely-used specifications such as UML [UML], BPMN [BPMN], MOF [MOF], XMI [XMI], DDS [DDS] and CORBA [CORBA], to name but a few significant ones.