Consensus

Kind: mechanism

Layer: Execution Core

Record: architecture:consensus

Severity: contextual

Scope: distributed system, agreement, consistency

Canonical: Ontology

A mechanism that lets a quorum of nodes commit one value, so every correct node ends up with the same value.

Listed in Architecture principles, after Leader Election and before Choreography.

Requires

• Quorum

Reinforces

• Consistency
• Fault Tolerance

Enables

• Agreed Single Value Across Nodes

Conflicts with

• Independent Node Decisions

In tension with

• Latency
• Availability

Tensions

• Consensus / Latency
• Consensus / Availability

Violated by

• Independent Node Decisions

Severity

• contextual

Category

• Control / Coordination / Centralization

Required by

• Total-Order Broadcast
• Leader Election

Linked from

• Causality / Ordering / Distributed Time
• Control / Coordination / Centralization
• Error Handling / Resilience
• Scalability / Performance / Optimization
• Transactions / State / Concurrency
• Control / Coordination / Centralization
• Quality Attributes
• Severity levels
• The resolutions