Architecture Decisions: Immutable ADRs, MADR Format & Rationale Capture

Last Audited: 2026-08-18

Tier-1 Platform Core

In Plain Language

Preventing architectural amnesia through version-controlled Architecture Decision Records (ADRs), status lifecycles, and change control.

Architecture Decision Records (ADRs): Preventing Architectural Amnesia

An Architecture Decision Record (ADR) is a short, version-controlled markdown document that captures a critical architectural choice, the context in which it was made, alternatives evaluated, and the accepted positive and negative tradeoffs. Instead of relying on ephemeral Slack threads or whiteboard memories, ADRs live directly in the Git repository alongside the code.

The Four Immutable ADR Lifecycle States

PROPOSED

Under active review by engineering and architecture teams; open for feedback and benchmarking spikes.

ACCEPTED

Formally approved by principal architects and stakeholders; represents active architectural law in the codebase.

SUPERSEDED

Replaced by a newer decision record (e.g. ADR-028 supersedes ADR-014); preserved immutably for historical audit trails.

DEPRECATED

Architecture pattern is being phased out; no new services may adopt this approach.

Interactive ADR Inspector: ADR-014 — Asynchronous Ingestion Pipeline for Medical Device Telemetry

Status: ACCEPTEDDate: 2026-06-12

Deciders: Alex Rivera (Principal Architect) • Dr. Elena Rostova (VP Medical Quality) • Samir Patel (Lead Platform Engineer)

1. Context & Problem Statement

Our medical monitoring platform receives continuous vitals telemetry (heart rate, SpO2, glucose) from 50,000+ connected wearable patient monitors. Under peak load, synchronous HTTP ingestion directly to PostgreSQL created connection pool exhaustion, leading to intermittent 504 Gateway Timeouts and potential telemetry packet loss. Regulatory mandate ISO 13485 Cl. 7.3.3 requires zero data loss for critical clinical vitals.

2. Architectural Decision Outcome

We will decouple telemetry ingestion by introducing an asynchronous Apache Kafka event streaming cluster with a redundant Redis cache layer. The public API gateway will validate the cryptographic JWT signature, push the raw telemetry payload to Kafka in <15ms, and return HTTP 202 Accepted. Dedicated consumer microservices will process validation, clinical threshold alerting, and persistent database writes in parallel.

✓ Positive Tradeoffs

API Gateway ingestion response time reduced from 340ms to 12ms (p95).
Ingestion tier can buffer up to 48 hours of telemetry during downstream database maintenance windows.
Achieved 100% telemetry delivery reliability with zero dropped patient packets.

⚠ Accepted Limitations / Maintenance

Introduces eventual consistency: telemetry records appear in the clinical dashboard with a 250ms–500ms lag.
Requires operational monitoring and disaster recovery setup for Apache Kafka cluster.

Regulatory Compliance Mapping: Satisfies ISO 13485 Clause 7.3.3 Design Inputs for clinical data integrity and ISO 27001 Control A.8.27 secure distributed architecture.

Standard Markdown Architectural Decision Record (MADR) Template

Markdown Template (docs/adr/ADR-000-template.md)

# [Short title of solved problem and decision]

* Status: [proposed | accepted | superseded by ADR-XXX | deprecated]
* Deciders: [List of decision authors & stakeholders]
* Date: [YYYY-MM-DD]

## Context and Problem Statement
[What is the context and challenge? What requirements or operational limits triggered this choice?]

## Decision Drivers
* [Driver 1, e.g. latency SLA < 50ms under peak load]
* [Driver 2, e.g. zero data loss requirement under ISO 13485]

## Considered Options
* [Option 1 - Short description]
* [Option 2 - Short description]

## Decision Outcome
Chosen option: "[Option 1]", because [justification with tradeoffs].

### Positive Consequences
* [e.g. 10x throughput improvement]
* [e.g. Simplified operational maintenance]

### Negative Consequences
* [e.g. Requires additional cloud worker instances]
* [e.g. Eventual consistency lag]

## Regulatory & Compliance Impact
[Mapping to ISO 13485 Cl. 7.3.3 / ISO 27001 Control A.8.27]

Try This With AI: Architecture Decision Record (ADR) Author

ADR Prompt

Use this prompt to convert engineering debate notes into an immutable, audit-ready MADR record:

"Act as a Principal Enterprise Software Architect. We just concluded an architectural discussion on: [DESCRIBE DECISION CONTEXT, OPTIONS, AND CHOSEN OUTCOME]. Author a complete Architecture Decision Record using the MADR 3.0 format: (1) Clear title and metadata, (2) Problem context with measurable metrics, (3) Explicit rationale for chosen option vs rejected alternatives, (4) Positive and negative consequences, and (5) ISO 13485 / ISO 27001 compliance notes."

Community Discussion & Feedback

Attributed peer feedback and official Netspective architecture notes.

Was this documentation helpful?(100% found this helpful • 0 ratings)

Leave Feedback or Question

○ Loading user info...

Discussion (0)

Loading discussion thread...