Distributed Agreement Algorithm

A Distributed Agreement Algorithm is an algorithm that can achieve consensus among distributed nodes in a distributed system.

• AKA: Distributed Consensus Algorithm, Agreement Protocol, Consensus Algorithm.
• Context:
  • It can typically coordinate Node Decisions through message passing.
  • It can typically handle Network Failures through fault tolerance mechanisms.
  • It can typically ensure Agreement Propertys through consensus rules.
  • It can typically maintain System Consistency through state synchronization.
  • It can typically provide Progress Guarantees through liveness propertys.
  • ...
  • It can often minimize Message Overhead through efficient protocols.
  • It can often reduce Decision Latency through optimization techniques.
  • It can often support Dynamic Topology through membership changes.
  • It can often enable Partial Synchrony through timing assumptions.
  • ...
  • It can range from being a Simple Distributed Agreement Algorithm to being a Complex Distributed Agreement Algorithm, depending on its distributed agreement protocol sophistication.
  • It can range from being a Deterministic Distributed Agreement Algorithm to being a Probabilistic Distributed Agreement Algorithm, depending on its distributed agreement decision guarantee.
  • ...
  • It can integrate with Distributed Systems for state management.
  • It can connect to Network Layers for message delivery.
  • It can interface with Application Layers for decision execution.
  • It can communicate with Monitoring Tools for consensus tracking.
  • It can synchronize with Storage Layers for state persistence.
  • ...
• Example(s):
  • Traditional Distributed Agreement Algorithms, such as:
    • Distributed Consensus Algorithms, such as:
      • Paxos Algorithm by Leslie Lamport for fault-tolerant consensus.
      • Raft Algorithm by Diego Ongaro for understandable consensus.
    • Byzantine Agreement Algorithms, such as:
      • PBFT Algorithm for byzantine fault tolerance.
      • HotStuff Algorithm for linear communication complexity.
  • Blockchain-Based Agreement Algorithms, such as:
    • Blockchain Consensus Algorithms, such as:
      • Bitcoin Nakamoto Consensus for cryptocurrency consensus.
      • Ethereum Proof-of-Stake for energy-efficient consensus.
    • Permissioned Blockchain Algorithms, such as:
      • Hyperledger Fabric PBFT for enterprise blockchain consensus.
      • Tendermint Core for instant finality consensus.
  • Specialized Agreement Algorithms, such as:
    • Leader Election Algorithms, such as:
      • Bully Algorithm for coordinator selection.
      • Ring Algorithm for token-based election.
  • ...
• Counter-Example(s):
  • Centralized Algorithms, which lack distributed coordination requirement.
  • Local Synchronizations, which lack global agreement scope.
  • Shared Memory Algorithms, which lack message-based consensus.
• See: Distributed Systems, Consensus Protocol, Fault Tolerance, Algorithm.

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