SysML Partners: Creators of SysML

Who created SysML?

SysML was created by the SysML Partners, an informal association of Systems Engineering experts and software modeling tool vendors that convened in 2003 to create a profile (dialect) of UML for Systems Engineering called SysML (Systems Modeling Language). The SysML Partners defined SysML as an open source specification that would satisfy the requirements of the Object Management Group's UML for Systems Engineering RFP, and their specifications included an open source license for distribution and use.

A Brief History of SysML

The SysML Partners were founded and chaired by Cris Kobryn, who previously chaired the successful UML 1.x and UML 2.0 architecture modeling language design teams. As Chair of the SysML Partners Kobryn coined the language name "SysML" (short for "Systems Modeling Language"), designed the original SysML logo, and organized the SysML core language design team as an open source specification project. David W. Oliver, Co-Chair of the INCOSE Model Driven Design Working Group and INCOSE Fellow, was a seminal contributor to the SysML Partners throughout the project. (See Acknowledgement in Memoriam below.) Sandy Friedenthal, chair of the OMG Systems Engineering Special Interest Group, served as Deputy Chair of the SysML Partners during the start of the project.

The SysML Partners submitted SysML Specification v. 0.9 to the OMG for review 10 Jan. 2005 (OMG document ad/05-01-03). After considering constructive feedback from the OMG, INCOSE, and the general public, the SysML Partners submitted their SysML Specification v. 1.0a for OMG technology adoption on 14 Nov. 2005 (OMG document ad/05-11-05). After more than 1.5 years of the OMG technology and political processes the OMG formally adopted the OMG SysML 1.0 specification (OMG document ptc/06-05-04) in July 2006.

There has been no major revision of OMG SysML 1.x since it was formally adopted by the OMG in July 2006. The OMG has only adopted minor revisions to the OMG SysML 1.x specification, the most recent minor revision is OMG SysML 1.4.

SysML Language Design Principles

The following fundamental design principles have guided the development of SysML:
Parsimony: SysML is based on a subset of UML that economically satisfies the basic requirements of the systems engineering community as defined in the UML for SE RFP. Additional constructs and diagram types are added to this UML subset only as needed to address derived system engineering requirements discovered during the language specification process. This disciplined application of Occam’s razor results in a more concise, yet more semantically expressive language which is easier to learn, implement and apply.
Reuse: SysML strictly reuses UML constructs wherever practical, and when modifications to UML are required, they are done in a manner that strives to minimize changes to the underlying language. Consequently, SysML is intended to be straightforward for UML vendors to implement. • Modularity: The principle of strong cohesion and loose coupling is applied to organize normative and non-normative language constructs into stereotype extension and model library packages.
Layering: Layering is used to organize the SysML profile in two ways. First, since SysML is defined as strict UML Profile, all SysML packages may be considered an extension layer of the underlying UML metamodel. Second, a SysML language constructs are organized into two levels of compliance, Basic and Advanced, which constitutes an additional layering.
Partitioning: Partitioning is used to organize conceptual areas within the same layer. SysML’s package structure, which is explained in the following section, partitions the SysML profile into packages that correspond to the language’s major diagram types. This partitioning is largely isomorphic with UML’s package structure, and is intended to facilitate reuse and implementation.
Extensibility: SysML supports the same extension mechanisms furnished by UML (metaclasses, stereotypes, model libraries), so that the language can be further extended for specific systems engineering domains, such as automotive, aerospace, manufacturing and communications.
Interoperability: SysML is aligned with the semantics of the ISO AP-233 data interchange standard to support interoperability among engineering tools, and inherits the XMI interchange from UML.

Reference: SysML Specification v. 1.0a, Section 6.1 Design Principles [14 Nov. 2005]

SysML Language Design Technical Approach

The following summarizes the technical approach followed by the SysML language designers in defining SysML as a dialect (profile) of UML 2:
• Parsimoniously extend UML constructs only as needed: Sparingly add new constructs to UML 2 only as needed to support Systems Engineering requirements as specified by the OMG's UML for Systems Engineering RFP;
• Reduce UML constructs not needed: Explicitly eliminate software-centric UML constructs not needed by SysML so that the SysML dialect will be simpler and less complex than the UML parent language, and therefore easier to learn and apply;
Support SysML + UML mixed language usage: Ensure that SysML constructs can be synergistically combined with UML 2 constructs in a model shared by Systems Engineers and Software Engineers, where the former use SysML and the latter use UML. The synergistic combination of SysML and UML should maximize requirements traceability and minimize semantic overlap between the two languages.
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SysML Partners

The main contributors to the SysML v. 1.0a specification follow:

Other SysML contributors

Other SysML contributors that include, but are not limited to, SysML Partners' SysML Specification v. 0.9 copyright holders:

SysML 1.0 & OMG Adoption

The SysML Partners completed their SysML v. 1.0a open source specification draft and submitted it to the OMG in November 2005. A series of competing specification proposals was followed by a "SysML Merge Team" proposal submission to the OMG in April 2006, which was adopted by the OMG as OMG SysML™ in July 2006.

Industry Recognition

  • 2006: The International Council on Systems Engineering (INCOSE) presented Kobryn with its Outstanding Service Award for his contributions to the development of the SysML.
  • 2007: The SD Times's editors named the SysML Partners as a winner in the "Modeling Category" of the SD Times 100, which recognizes the leaders and innovators of the software development industry.

Acknowledgement in Memoriam
The seeds of what eventually grew into the SysML Partners open source specification project began with collaborations between David W. Oliver (1932-2011) and Cris Kobryn starting in 2001. During that time Oliver was an INCOSE Fellow who served as Co-Chair of the INCOSE Model Driven Design Working Group, and Kobryn was consumed with leading the UML2 Partners visual modeling language design team.

Kobryn was impressed by Oliver's vision and passion for a UML for Systems Engineering profile (UML dialect) backed by his Systems Engineering expertise. Both Oliver and Kobryn realized early that UML software components and Systems Engineering hardware components were more similar than dissimilar. Convinced that the two kinds of components could be unified syntactically and semantically, Kobryn subsequently directed his software-centric UML2 Partners team to reduce gratuitous software-centric aspects of the UML 2.0 specification draft so that it could potentially serve as a syntactic and semantic foundation for a future UML for Systems Engineering profile.

Without Oliver's passion and vision, which inspired this tedious but essential UML 2.0 foundation re-work, it is unlikely that the SysML open source specification project could have been completed in a timely manner.
Systems Modeling Language and SysML are not usable as trademarks (see SysML open source project Legal Notices). Unified Modeling Language, UML and OMG SysML are trademarks of the Object Management Group. All other product and service names mentioned are the trademarks of their respective companies.