Areas of focus of SysML
The constructs, diagrams, and semantics of SysML are grouped around four areas of focus:
Requirements modeling
Improved behavior modeling
Blocks (improved structure modeling/semantics with blocks)
Parametrics
Requirements modeling: SysML allows the representation of requirements as model elements. Hence requirements become an integral part of the product architecture. The language offers a flexible means to represent
Improved behavior modeling: SysML uses UML constructs for interaction diagrams and state machines and enhances activity diagram semantics, including the addition of semantics to enable modeling of continuous behavior.
Improved structure modeling: SysML provides a basic structural element called a Block, whose aim is to provide a
Parametrics: SysML provides semantics for reasoning about properties of blocks and their relationships, and allows the integration of engineering analysis with design models. Parametrics in SysML are based on constraint
parameters. More specifically, constraints are properties in blocks named ConstraintProperty and are typed by ConstaintBlocks. A constraint block defines
an expression and the attributes that represent its parameters. SysML does not prescribe any language to represent the expressions or provide a solver for it. This is typically offered within the usage of a tool optimized for constraint solving.
We will discuss requirements modeling, blocks, and parametrics in turn, but not changes to activity diagrams, state machines, or other material pertaining to behavior as changed in SysML.
Requirements modeling
Requirements have been traditionally represented as text (accompanied with figures and drawings) and stored in files or databases. The requirements describe all the product functions and the constraints under which these functions should be realized:
