Architectural Primitive · v1.0

BSFG

Bidirectional Store-and-Forward Gateway

ISA-95 · IEC 62264 · IEC 62541-14 · EIP

Problem: Industrial plants integrating modern IT/OT systems face critical resilience gaps. When enterprise systems (ERP, cloud, corporate networks) become unreachable due to network partitions, GC pauses, or infrastructure failures, plant operations typically face blocking producers, data loss, or forced shutdowns.

Solution: BSFG is a hexagonal boundary primitive implementing a four-buffer topology (Ingress Store/Forward, Egress Store/Forward) that decouples connectivity from communication, enabling autonomous operation. When the boundary seals, both zones continue operating using local durable buffers; when reconnected, they achieve eventual consistency without duplication.

Guarantee: Producer non-blocking writes, effectively-once delivery at the boundary, and transactional autonomy per zone — with zero shared state or distributed transactions.

Documentation

Executive Brief

1-PAGER

The concise summary of the BSFG architecture and its role in industrial resilience. Covers the IT/OT integration challenge, the four-buffer topology mechanism, core guarantees, and standards alignment.

Key Topics:

  • The resilience gap problem in IT/OT integration
  • Four-buffer decomposition: ISB, IFB, ESB, EFB
  • Producer non-blocking, effectively-once boundary, 5-day swappability, no shared state
  • Standards compliance: ISA-95, IEC 62264, OPC UA PubSub, Enterprise Integration Patterns

Technical Overview

2-PAGER

Intermediate-level technical documentation for architects and engineers. Covers the autonomy model (Normal vs. Autonomous modes), the five-step handoff protocol, hexagonal architecture with TypeScript interface contracts, backend matrix options, and proof-by-exclusion via EIP analysis.

Key Topics:

  • Autonomy requirement and mode transitions
  • Objectives vs. non-objectives table
  • Frontier semantics and cursor management
  • Interface contracts: StoreBuffer, ForwardBuffer
  • Backend matrix: Kafka, PostgreSQL, S3, Redis, etcd
  • Backpressure and safety analysis

Technical Specification (Normative)

5-PAGER

Full normative specification for implementers and standards compliance. Covers foundational constraints (objectives O1–O4, non-objectives N1–N7), minimal factorization concept, formal TypeScript interface contracts, operational modes (Normal/Autonomous/Reconciliation), failure mode analysis, threat model, and safety certification context (IEC 61508).

Key Topics:

  • Formal objectives and non-objectives
  • Minimal factorization principle
  • Typed interfaces for pluggable backends
  • Data integrity and idempotency without active reconciliation
  • Failure mode analysis and threat model tables
  • Verification matrix and safety certification roadmap

Hexagonal Architecture & BSFG

BACKGROUND

Brief explainer on Alistair Cockburn's hexagonal (ports and adapters) architecture pattern and how it applies to BSFG. Illustrates the separation between BSFG core logic (handoff protocol, cursor advancement) and pluggable storage backends.

Key Concepts:

  • Port: Interface definition (what). Example: StoreBuffer, ForwardBuffer, CursorTracker
  • Adapter: Concrete implementation (how). Example: Kafka adapter, PostgreSQL adapter, S3 adapter, Redis adapter
  • Application Core: BSFG business logic, isolated from storage implementations
  • Benefits: testability, deployment flexibility, 5-day backend swappability

Interactive Model

Explore the four-buffer topology and handoff protocol in an interactive 3D scene. Click to produce or consume data from the ingress and egress lanes. Watch buffer fill states update in real time and observe how the gate controls flow between zones.

→ Open 3D Interactive Model

Standards & Normative References

BSFG aligns with the following industrial standards and patterns:

ISA-95 IEC 62264 IEC 62541-14 OPC UA PubSub EIP #101 EIP #128 EIP #201 IEC 61508