SysML Partners: Creators of the SysML

A Brief History of SysML

• SYSML 1.0 Alpha MILESTONE [Nov. 2005] The SysML Partners submitted their SysML Specification v. 0.9 draft to the OMG for review 10 Jan. 2005. After processing voluminous constructive feedback from the OMG, INCOSE, and the general public, the SysML Partners submitted their SysML Specification v. 1.0 Alpha draft to the OMG for technology adoption on 14 Nov. 2005. The primary technical contributors to the SysML Partners's SysML 1.0 Alpha specification included Chris Sibbald (Telelogic), Thomas Wiegert (Motorola), Brian Willard (Northrop Grumman), and Cris Kobryn (PivotPoint Technology; Chair & Chief Editor). Auxiliary SysML 1.0 Alpha technical contributors, who also co-authored content for competing SysML specifications, included Conrad Bock (NIST), Rick Steiner (Raytheon), Laurent Balmelli (IBM), and Roger Burkhart (John Deere).
• 1.5 YEARS LATER: OMG SYSML 1.0 MILESTONE [July 2006] After more than one-and-a-half years of contentious OMG technology and political processes, the OMG formally adopted the OMG SysML 1.0 specification in July 2006. Subsequently, the Software Development Times' (SD Times's) Editors bestowed the SysML Partners with its "SD Times 100" award for industry leadership in the “Modeling” category.
• 15+ YEARS AFTER ADOPTION & COUNTING: No Major Revision Yet, OMG SYSML 2.0 RFP "Work In Progress" Although there have been multiple minor revisions to the OMG SysML 1.x specification since it was adopted in 2006 (the current minor revision is OMG SysML 1.5 [2017], there has been no major revision to OMG SysML since its adoption in 2006. However, the OMG issued an RFP for OMG SysML v. 2.0 in December 2017. Given the glacial progress of the OMG SysML 1.x revision process, it appears unlikely that a OMG SysML 2.0 major revision will be formally adopted and implemented prior to 2021.

Industry Recognition

The innovative work of the SysML Partners's Language Design team has been by recognized by both professional societies and industry analysts:

• 2006: The International Council on Systems Engineering (INCOSE) presented Cris Kobryn, Chair & Chief Editor of the SysML Partners, with its Outstanding Service Award for his contributions to the development of the SysML.
• 2007: The Software Development Times' (SD Times's) Editors bestowed the SysML Partners with its "SD Times 100" award for industry leadership in the “Modeling” category.

SysML Language Design Principles

The following fundamental design principles guided the development of the SysML open source specification:

• 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. 1.0 Alpha, Section 6.1 Design Principles [14 Nov. 2005].

SysML Language Design Technical Approach

In consideration of the SysML Language Design Principles outlined above, the following summarizes the technical approach followed by the SysML Parthers' Language Design team in defining SysML as a dialect (profile) of UML 2, rather than as a new language with a unique metamodel:

• 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.