The Enterprise Toast Protocol (ETP) is the Department's answer to a
problem no one raised: how do you make toast at enterprise scale with full observability,
distributed consensus, and a comprehensive audit trail? ETP v2.0 delivers exactly that,
adding only 3 minutes and 47 seconds to the average toast preparation time.
Your bread enters a Kafka topic (raw.bread.ingest), is validated by a
schema registry, and queued for assignment to one of three independent toasting nodes.
All three nodes must agree on browning level before any heat is applied. Disagreements
are resolved via Raft consensus. In practice, the nodes agree immediately and the
delay is attributable to the consensus negotiation overhead.
System Architecture
- Ingestion Layer: Bread is placed in the DQE-certified Input Tray (Form DQE-ETP-01 required). Dimensions, hydration level, and grain classification are logged.
- Queue: Bread enters
raw.bread.ingest Kafka topic. Retention: 7 days. Replication factor: 3.
- Schema Validation: Bread metadata validated against Avro schema v4.1. Sourdough requires additional field:
tang_coefficient.
- Consensus Round: All three toasting nodes propose a browning level (Pantone 729C to 730C). Raft leader commits the agreed value. Average consensus time: 340ms.
- Heat Application: Committed browning instruction dispatched to physical toasting element. Monitored by Prometheus. Alerted via PagerDuty if variance exceeds ±2°C.
- Egress: Toast delivered to Output Tray. Delivery event published to
toast.completed topic. Consumer groups notified.
Service Level Agreement
- Toast Availability: 99.9% (excludes scheduled Kafka rebalancing windows)
- P50 latency: 2 min 14 sec
- P99 latency: 4 min 03 sec
- Browning accuracy: ±1 Pantone unit
- Data retention: All toast events stored for 90 days for audit purposes
Known Limitations
- Bagels require a separate partition key and are subject to an additional 45-second schema negotiation
- Gluten-free bread triggers a manual review step (Form DQE-ETP-GF) pending allergen classification update
- Node split-brain during butter application phase is a known issue; workaround documented in Runbook v3.2
- The toaster cannot currently be unplugged without filing a Change Request (DQE-CHG-INFRA)
Comparison to Legacy Toaster
- Legacy toaster: 2 minutes, 1 component, 0 forms required
- Enterprise Toast Protocol: 4 minutes average, 14 components, 3 forms required
- Improvement: Comprehensive audit trail, distributed fault tolerance, 12 Grafana dashboards
