MBSE — Model-Based Systems Engineering
What Model-Based Systems Engineering is and how NexoGraph implements its core principles.
Model-Based Systems Engineering (MBSE) is a formalized methodology that uses coherent, connected models as the primary means of systems engineering communication, design, and documentation — replacing the traditional document-centric approach where requirements live in Word files, interfaces in spreadsheets, and architecture in static PDFs.
MBSE is the foundational methodology behind NexoGraph. Every architectural decision in the tool is rooted in MBSE principles.
Document-Centric vs Model-Based
| Aspect | Document-centric | Model-based (NexoGraph) |
|---|---|---|
| Source of truth | Distributed documents | Single connected graph model |
| Traceability | Manual cross-references | Formal reference relations in Neo4j |
| Impact analysis | Manual, error-prone | Automated graph traversal |
| Consistency checking | Review meetings | AI batch consistency-check jobs |
| Change propagation | Notify and hope | Invalidation flags on linked entities |
| Versioning | File revisions | Entity-level revision history |
| Tooling | Word + Excel + PDFs | Structured API + portal + programmatic access |
Core MBSE Concepts
Single Source of Truth
All systems engineering artefacts — stakeholder needs, requirements, stakeholder definitions, user personas, stories — live in one connected graph. There is no secondary document that can drift out of sync.
Model, View, Viewpoint
A model is the complete graph of entities and their relations. A view is a projection of that model from a particular perspective (e.g., a stakeholder's needs, a subsystem's requirements). A viewpoint defines the rules for constructing such a view. This matches the ISO 42010 architecture description vocabulary — see the ISO 42010 page.
Digital Thread
The digital thread is the connected chain of traceable data that links every artefact across the product lifecycle — from stakeholder need through requirement, design decision, implementation, test, and operation. In NexoGraph, reference relations form the edges of this thread. Coverage analysis detects broken or missing threads.
Bidirectional Traceability
Every artefact can be queried forward (what does this need produce?) and backward (why does this requirement exist?). Graph traversal makes this instantaneous regardless of model size.
NexoGraph as an MBSE Tool
| MBSE principle | NexoGraph implementation |
|---|---|
| Formal model | Neo4j property graph — entities are nodes, relations are typed edges |
| Model elements | Ten entity types: Stakeholder, Need, Requirement, User, UserStory, CustomerFeature, SystemCapability, BusinessCase, Package, BusinessCaseCell |
| Model connections | Reference relations with defined semantics (HAS_STAKEHOLDER_NEED, HAS_USER_NEED, TELLS, EXPRESSES, INFORMS, REFINES_INTO, SATISFIED_BY, ENABLED_BY) |
| Views / viewpoints | Root collections as first-class projections of the model |
| Decomposition | Package hierarchy with typed PackageType (STAKEHOLDER_REQUIREMENTS, STAKEHOLDER, USER_NEEDS, CUSTOMER_FEATURES, SYSTEM_CAPABILITIES, etc.) |
| Lifecycle governance | Lifecycle service with state machine per entity type — draft → review → approved → deprecated |
| Model authoring | AI inline suggestion service for requirement and need writing |
| Model validation | Batch consistency-check jobs that detect conflicting requirements |
| Impact analysis | Reference relation invalidation flags propagate change signals |
| Digital thread | Traceability query from any entity to upstream needs and downstream artefacts |
MBSE Adoption Levels
INCOSE identifies three levels of MBSE adoption. NexoGraph targets Level 2 today and Level 3 by design:
| Level | Description | NexoGraph status |
|---|---|---|
| Level 1 — Model awareness | Models supplement documents; no integration | Below NexoGraph's scope |
| Level 2 — Model as reference | Models are the authoritative source; queries replace document searches | Current state |
| Level 3 — Model as integration backbone | Models drive downstream tools (CAD, simulation, test management) via APIs | API layer + planned integrations (JIRA, PLM, DOORS) |
Related Standards
MBSE as a methodology is enabled by and aligned with several standards covered in this documentation:
| Standard | Role in MBSE |
|---|---|
| INCOSE SE Handbook | Defines MBSE as the recommended practice for modern systems engineering |
| ISO 15288 | Life cycle process framework that MBSE models are organized around |
| ISO 29148 | Requirements quality characteristics enforced within the model |
| ISO 42010 | View/viewpoint vocabulary used by NexoGraph's root collections and packages |
| OMG SysML | De facto modelling language for MBSE; NexoGraph's metamodel is SysML-aware |