Distributed Systems

Long-running distributed transactions as a sequence of local transactions plus compensating actions, with orchestration/choreography and isolation trade-offs.

The CanCommit, PreCommit, and DoCommit structure of 3PC, why it was proposed to reduce blocking, and why partitions still make it uncommon in practice.

A conceptual comparison between resource-level two-phase commit and application-level TCC, both of which separate preparation from the final decision.

How to commit business state and an outgoing event in one local database transaction, then asynchronously publish with retries and idempotent consumption.

A compact implementation-oriented view of two-phase commit and XA resource coordination.

An implementation-oriented summary of application-level Try/Confirm/Cancel transactions and their idempotency and compensation requirements.

Using an MQ for retryable notifications while keeping an authoritative query path for receivers that miss or cannot process a callback.

RocketMQ's half-message, local-transaction, commit/rollback, and transaction-check protocol for coupling producer-side local state with message visibility.

Why distributed nodes need consensus, how Paxos, Raft, ZAB, and Gossip differ, and how consensus relates to strong or eventual consistency.

Basic Paxos roles and two-phase decision flow, why contention is expensive, and how Multi-Paxos uses a stable leader to make repeated consensus practical.