MBSE METHOD BRIEF · SysML-based, INCOSE-sponsored
OOSEM is a top-down, scenario-driven approach to model-based systems engineering that treats a system as a set of interacting objects — allocating behavior to structure through a repeated, iterative cycle rather than a single pass of decomposition.
Originated 1998 · developed jointly by Lockheed Martin and the INCOSE OOSEM Working Group · modeled in SysML
Simplified from INCOSE's OOSEM activity model — the method cycles through these activities repeatedly rather than completing them once in sequence.
01 — What it is
OOSEM applies object-oriented analysis and design concepts — long established in software engineering — to the broader practice of systems engineering. It is a tool- and vendor-neutral methodology: no single company owns an OOSEM product, and it can be carried out with any SysML-capable modeling tool paired with a requirements management tool.
The method covers the core activities any systems engineer would recognize — needs analysis, requirements analysis, architecture definition, trade studies, and verification — but organizes them around objects and their interactions rather than a purely functional decomposition. That framing is meant to ease integration with object-oriented software development, hardware development, and test processes downstream.
02 — How it works
OOSEM starts from operational scenarios and works down: black-box behavior is defined first, then allocated to a logical architecture of interacting objects, then refined into a physical design. Each pass through the cycle decomposes objects further, allocates more detailed behavior, and produces requirements specific enough to hand to implementers.
The approach shares its top-down, scenario-driven character with methods such as the Harmony process and the Rational Unified Process for Systems Engineering (RUP SE), and it draws on techniques including causal analysis, logical decomposition, node distribution analysis, control strategy definition, and parametrics to handle different kinds of system concerns as they arise.
03 — Core activities
Establish the problem the system must solve and the stakeholders whose needs define success, before any solution language enters the picture.
Translate needs and operational scenarios into black-box system requirements, capturing required behavior without presupposing a design.
Allocate behavior to a logical architecture of interacting objects, then decompose those objects into a physical architecture of components.
Compare candidate architectures and parameter sets against measures of effectiveness to justify design decisions.
Refine the physical architecture into a design specific enough to be implemented, tested, and integrated.
Confirm the delivered system satisfies its requirements and, ultimately, the original stakeholder needs — feeding lessons back into earlier activities as needed.
04 — INCOSE resources
OOSEM is stewarded by INCOSE's Object-Oriented Systems Engineering Method Working Group. These are the primary places to find current working-group activity, charters, and background material.
Current charter, scope, and ongoing activity for the group that maintains and evolves OOSEM — including work to align it with SysML v2.
incose.org/group/object-oriented-se-method-working-group →The working group's founding charter document: purpose, scope, history, and how OOSEM relates to methods like Harmony and RUP SE.
incose.org — WG charter PDF →An INCOSE Chesapeake Chapter tutorial introducing OOSEM alongside SysML, built around A Practical Guide to SysML. A good entry point before reading primary papers.
incose-cc.org — tutorial page →A reference summary of OOSEM maintained on the OMG-hosted MBSE wiki, with a bibliography of the foundational papers and books.
omgwiki.org — MBSE:OOSEM →A marketplace summary from an INCOSE International Workshop covering the working group's history, product roadmap, and planned inputs to the SE Handbook and SysML spec.
incose.org — IW2019 brief PDF →The International Council on Systems Engineering — for the Systems Engineering Handbook, chapters, certification, and the full list of working groups beyond OOSEM.
incose.org →06 — Community & tooling
OOSEM is method-only — it doesn't prescribe a tool. These are the open-source communities building the SysML/KerML tooling and model management infrastructure it's commonly practiced with.
The open-source Model-Based Systems Engineering environment, including Model Management System (MMS) tooling for storing and serving system models.
openmbee.org →The community forum and resource hub for SysML v2 and KerML, covering the transition from SysML v1 and the surrounding open ecosystem.
opensysml.org →07 — Further reading