Systems modeling language: Difference between revisions

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The '''Systems Modeling Language''' ('''SysML'''), is a [[___domain-specific modeling]] language for [[systems engineering]]. It supports the specification, analysis, design, verification and validation of a broad range of systems and systems-of-systems. SysML was originally developed by an [[open source]] specification project, and includes an open source license for distribution and use. SysML is defined as an extension of a subset of the [[Unified Modeling Language]] (UML) using UML's profile mechanism.

SysML offers systems engineers several noteworthy improvements over UML, which tends to be software-centric. These improvements include the following:<ref name="faq">{{cite web|author=SysML Partners|title=SysML FAQ|url=http://www.sysmlforum.com/faq.htm|accessdate=2006-07-02}}</ref>

SysML is notable for the wide range of systems concepts it can model. These system concepts may include hardware, software, information, processes, personnel, and facilities. In an automotive application, for example, the language can be used to specify mechanical objectives and constraints such as maximum acceleration, [[curb weight]], [[air conditioning]] performance, and interior cabin [[acoustical engineering|noise management]]. It can specify electrical parameters ranging from the [[FM radio]] [[tuning sensitivity]] to the [[real-time]] response of the [[antilock brake|anti-lock braking]] control electronics. It can specify and model the [[embedded software]] used to control the on-board automotive computers. Finally, it can model the factories used to build the car, as well as the interfaces between the organizations that work in the factory. SysML does not replace the simulation tools used to model specific subsystems, but rather provides the "glue" to model the interaction between subsystems.

* SysML's semantics are more flexible and expressive. SysML reduces UML's software-centric restrictions and adds two new diagram types, Requirement and Parametric diagrams. The former can be used for requirements management; the latter can be used for performance analysis and quantitative analysis. As a result of these ehancements, SysML is able to model a wide range of systems, which may include hardware, software, information, processes, personnel, and facilities.

* SysML is a smaller language that is easier to learn and apply. Since SysML removes many of UML's software-centric and gratuitous constructs, the overall language is smaller as measured both in diagram types and total constructs.

* SysML allocation tables support common kinds of allocations. Whereas UML provides only limited support for tabular notations, SysML furnishes flexible allocation tables that will support requirments allocation, functional allocation, and structural allocation. This capability facilitates automated [[verification]] and [[validation]] (V&V) and gap analysis.

* SysML model management constructs support models, views, and viewpoints. These constructs extend UML's capabilities and are architecturally aligned with IEEE-Std-1471-2000 (IEEE Recommended Practice for Architectural Description of Software Intensive Systems).

The advantages of SysML over UML for systems engineering become more obvious if you consider an example, modeling an automotive system. With SysML you can use Requirement diagrams to efficiently capture functional, performance and interface requirements, whereas with UML you are subject to the limitations of Use Case diagrams to define high-level functional requirements. Likewise, with SysML you can use Parametric diagrams to precisely define performance and mechanical constraints such as maximum acceleration, [[curb weight]], [[air conditioning]] capacity, and interior cabin [[acoustical engineering|noise management]]. UML provides no straightforward mechanism to capture this essential performance and mechanical information.

A noteworthy improvement of SysML over the [[Unified Modeling Language|UML]] is its support for [[requirements modeling]]. During the design process, designers and users of specific sub-systems can communicate the design criteria using several alternative design formats including diagrams, tables, and tree structures. The requirements provide a checkable interface and documentation of the evolution of the system design over time.

As for the rest of the automotive system, SysML enhanced Activity and State Machine diagrams can be used to specify the [[embedded software]] control logic for the on-board automotive computers. Other SysML structural and behavioral diagrams can be used to model factories that build the automobiles, as well as the interfaces between the organizations that work in the factories.

== History ==

The SysML initiative has its origins in a January 2001 decision by the [[INCOSE|International Council on Systems Engineering]] (INCOSE) Model Driven Systems Design workgroup to customize the UML for systems engineering applications. Following this decision, INCOSE and the [[Object Management Group]] (OMG), which maintains the UML specification, jointly chartered the OMG Systems Engineering Domain Special Interest Group (SE DSIG) in July 2001. The SE DSIG, with support from INCOSE and the [[ISO 10303|ISO AP 233]] workgroup, developed the requirements for the modeling language, which were subsequently issued by the OMG as part of the ''UML for Systems Engineering Request for Proposal'' (UML for SE RFP; OMG document ad/03-03-41) in March 2003.<ref name="rfp">{{cite web|author=OMG SE DSIG|title=UML^TM for Systems Engineering RFP|url=http://syseng.omg.org/UML_for_SE_RFP.htm|accessdate=2006-06-29}}</ref>

In mid-2003 the ''SysML Partners'',<ref>{{cite web|url=http://www.sysml.org/partners.htm|title=SysML Partners|accessdate=2006-06-29}}</ref> an informal association of industry leaders and tool vendors co-chaired by [[Sanford Friedenthal]] and [[Cris Kobryn]], organized an open source specification project to develop the SysML in response to the "UML for Systems Engineering" RFP. The SysML 1.0a open source specification was completed and submitted to the OMG in November 2005.<ref name="sysml faq">{{cite web|author=SysML Partners|title=SysML FAQ|url=http://www.sysmlforum.com/faq.htm|accessdate=2006-06-29}}</ref> The SysML 1.0a open source specification was completed and submitted to the OMG in November 2005. After a series of competing specification proposals, a "SysML Merge Team" proposal was proposed to the OMG in April 2006. This proposal is now being finalized via the OMG adoption process.

== OMG SysML ==