Abstract

From 2015 to 2021 OMG’s Systems Modeling Language (SysML, see https://www.omgsysml.org/) specification has undergone a substantial overhaul and upgrade, culminating in version 2 per September 2021. SysML was first released in 2008, and from 2010 onwards, a succession of incremental improvements, up to v1.6 in 2019, have been implemented in model-based systems engineering (MBSE) tools. SysML is used successfully on many industrial projects, in sectors such as aerospace, defence, automotive and civil infrastructure. It has become the de facto international standard for expressing systems engineering models, and was also adopted as the ISO/IEC 19514 standard in 2017. However, since SysML v1.x builds on top of the Unified Modeling Language specification (UML, see https://www.omg.org/spec/UML/), it inherits a number of concepts from this object-oriented software engineering standard. This can be considered both a strength and a weakness. A strength because mature UML tools could be adapted with reasonable investment to support SysML, and it provided good coverage for software-intensive systems. However, a weakness too, because the software engineering heritage created barriers for the uptake by systems engineers, and in general by engineers without a strong software engineering background. A major concern with SysML v1 is that the learning curve for systems engineers is quite steep, and unnecessarily complicated in some areas. This was also acknowledged at OMG and in 2015 work started on collecting user requirements for a RFP (Request for Proposal) for Version 2. The goal was to address all lessons learnt from the initial years of industrial usage. Since such major overhaul can only be afforded every 10 years or so, this preparation was taken very seriously and performed by a broad group end-users – representing different industry sectors and stakeholder organizations – as well as MBSE tool vendors. This resulted in two extensive RFPs: one for the language (2017), and one for the Application Programming Interface (API) and Services (2018). Since early 2018, the SysML v2 Submission Team (SST) team – consisting of roughly 180 experts from around 80 organisations –– has been developing the second version of SysML. The paper will provide an overview of the new and enhanced capabilities of SysML version 2. The focus will be on how it can assist in the coordination and harmonisation of model-based engineering across all engineering disciplines in teams working on complex systems. Such coordination is of course one of the main responsibilities of the systems engineering discipline. Integrated use of models for both problem specification as well as solution development, verification and validation will be addressed. Sharing information common to multiple discipline models is essential, and the new SysML v2 API is expected to become a key enabler to this end. Finally an outlook on further development regarding SysML v2 will be provided. The author has been involved in SysML development since 2009. He is an active member of the SysML v2 Submission Team as well as the NAFEMS/INCOSE Systems Modeling and Simulation WG.