Key Points:
- Introduced by Leslie Lamport in 1989.
- Solves the consensus problem in asynchronous distributed systems.
- Ensures all nodes agree on a single value despite network issues or node failures.
- Operates in three phases: Prepare, Promise, and Accept.
- Three roles: Proposer, Acceptor, and Learner (optional).
Paxos Phases:
- Prepare Phase: Proposer sends “prepare” message with unique proposal number.
- Promise Phase: Acceptors respond with “promise” message, indicating no lower-numbered proposals.
- Accept Phase: Proposer sends “accept” message with proposed value; Acceptors validate.
Roles:
- Proposer: Initiates consensus process.
- Acceptor: Validates proposals.
- Learner: Observes consensus process (optional).
Benefits:
- Fault tolerance.
- Scalability.
- Flexibility.
Variations:
- Basic Paxos.
- Fast Paxos.
- Generalized Paxos.
Use Cases:
- Distributed databases.
- Private blockchain networks.
- Financial institutions.