SysML FAQ: What is the Systems Modeling Language (SysML)?
What is the Systems Modeling Language (SysML)?
Question Variant(s): What is SysML?; What is OMG SysML?
Definition
Systems Modeling Language (SysML): SysML is a general-purpose architecture modeling language for Systems Engineering applications.
- SysML supports the specification, analysis, design, verification, and validation of a broad range of systems and systems-of-systems. These systems may include hardware, software, information, processes, personnel, and facilities.
- SysML is a dialect of UML 2, and is defined as a UML 2 Profile. (A UML Profile is a UML dialect that customizes the language via three mechanisms: Stereotypes, Tagged Values, and Constraints.)
- SysML is an enabling technology for Model-Based Systems Engineering (MBSE).
The SysML was originally created by the SysML Partners' SysML Open Source Specification Project in 2003. The SysML was adapted and adopted by the Object Management Group (OMG) as OMG SysML in 2006. For more information about the current version of OMG SysML, see the SysML FAQ: What is the current version of SysML?.
SysML Diagram Taxonomy
The SysML is composed of nine (9) diagram types and Allocation Tables for mapping language elements across diagram types:
| Diagram Name | Diagram Type | UML 2 Analog | SDLC Usage | Essential AGILE SYSML? |
Dynamic Sim † |
Math Sim ‡ |
Auto Code Gen |
Rigor | Semi | Informal |
|---|---|---|---|---|---|---|---|---|---|---|
| Requirement diagram (req) | Static Structure [Declarative] |
N/A | Requirements Analysis | |||||||
| Use Case diagram (uc) | Behavior * [Non-Simulatable] |
Use Case | Requirements Analysis | |||||||
| Activity diagram (act) | Dynamic Behavior [Simulatable] |
Activity [minor mods] |
System Analysis, Functional Analysis, System Design |
|||||||
| Sequence diagram (sd) | Dynamic Behavior [Simulatable] |
Sequence | System Design | |||||||
| State Machine diagram (stm) | Dynamic Behavior [Simulatable] |
State Machine | System Analysis, System Design |
|||||||
| Block Definition Diagram (bdd) | Static Structure [Black Box Definition] |
Class [moderate mods] |
System Analysis, System Design |
|||||||
| Internal Block Diagram (ibd) | Static Structure [White Box Usage] |
Composite Structure [moderate mods] |
System Analysis, System Design |
|||||||
| Parametric Diagram (par) | Static Structure [White Box Usage] |
N/A | System Analysis, System Design |
|||||||
| Package diagram (pkg) | Static Structure [Grouping] |
Package [minor mods] |
All SDLC phases | |||||||
| Allocation Table | N/A [Relationship Matrix] |
N/A | All SDLC phases | |||||||
†: Dynamic Simulation (a.k.a. Dynamic System Simulation) refers to the capability of a computer program to execute the time-varying behavior of a system of interest. In general, with the exception of Use Case diagrams, SysML and UML 2 Behavior diagrams are potentially capable of Dynamic System Simulation.
‡: Mathematical Modeling & Simulation (a.k.a. Mathematical ModSim, Mathematical M&S, Parametric Simulation) refers to the capability of a computer program to execute the a mathematical model of the behavior of a system of interest, where the model is defined as a set of mathematical equations. When properly defined and applied, Parametric diagrams are capable of Mathematical ModSim; no other SysML or UML 2 diagrams are capable of this.
*: Although Use Case diagrams are generally classified as Behavior diagrams by both the OMG SysML and UML 2 specifications, their Behavioral semantics are ambiguous and incomplete. Whereas Activity, Sequence, and State Machine diagrams are Turing Complete and their dynamic behavior can be simulated or executed, Use Cases diagrams are not Turing Complete and are not simulatable.
SysML Diagram Taxonomy
The SysML is composed of nine (9) diagram types and Allocation Tables for mapping language elements across diagram types:
| Diagram Name | Diagram Type | UML 2 Analog | SDLC Usage | Essential AGILE SYSML? |
Dynamic Sim † |
Math Sim ‡ |
Auto Code Gen |
Rigor | Semi | Informal |
|---|---|---|---|---|---|---|---|---|---|---|
| Requirement diagram (req) | Static Structure [Declarative] |
N/A | Requirements Analysis | |||||||
| Use Case diagram (uc) | Behavior * [Non-Simulatable] |
Use Case | Requirements Analysis | |||||||
| Activity diagram (act) | Dynamic Behavior [Simulatable] |
Activity [minor mods] |
System Analysis, Functional Analysis, System Design |
|||||||
| Sequence diagram (sd) | Dynamic Behavior [Simulatable] |
Sequence | System Design | |||||||
| State Machine diagram (stm) | Dynamic Behavior [Simulatable] |
State Machine | System Analysis, System Design |
|||||||
| Block Definition Diagram (bdd) | Static Structure [Black Box Definition] |
Class [moderate mods] |
System Analysis, System Design |
|||||||
| Internal Block Diagram (ibd) | Static Structure [White Box Usage] |
Composite Structure [moderate mods] |
System Analysis, System Design |
|||||||
| Parametric Diagram (par) | Static Structure [White Box Usage] |
N/A | System Analysis, System Design |
|||||||
| Package diagram (pkg) | Static Structure [Grouping] |
Package [minor mods] |
All SDLC phases | |||||||
| Allocation Table | N/A [Relationship Matrix] |
N/A | All SDLC phases | |||||||
†: Dynamic Simulation (a.k.a. Dynamic System Simulation) refers to the capability of a computer program to execute the time-varying behavior of a system of interest. In general, with the exception of Use Case diagrams, SysML and UML 2 Behavior diagrams are potentially capable of Dynamic System Simulation.
‡: Mathematical Modeling & Simulation (a.k.a. Mathematical ModSim, Mathematical M&S, Parametric Simulation) refers to the capability of a computer program to execute the a mathematical model of the behavior of a system of interest, where the model is defined as a set of mathematical equations. When properly defined and applied, Parametric diagrams are capable of Mathematical ModSim; no other SysML or UML 2 diagrams are capable of this.
*: Although Use Case diagrams are generally classified as Behavior diagrams by both the OMG SysML and UML 2 specifications, their Behavioral semantics are ambiguous and incomplete. Whereas Activity, Sequence, and State Machine diagrams are Turing Complete and their dynamic behavior can be simulated or executed, Use Cases diagrams are not Turing Complete and are not simulatable.
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