Mastering Distributed Transactions with Seata: Architecture and Step‑by‑Step Guide

Seata Overview

Seata (Simple Extensible Automatic Transaction Architecture) is an open‑source, high‑performance distributed transaction framework released by Ant Financial/Alibaba. Its primary goal is to let developers use distributed transactions as easily as local transactions.

Architecture Components

TC (Transaction Coordinator) : The global transaction control center. It maintains global transaction state, coordinates commit/rollback of branch transactions, manages session information, and is typically deployed as an independent Seata Server.

TM (Transaction Manager) : Located at the business initiator (e.g., order service). It starts global transactions, commits or rolls them back, and communicates with TC automatically via the @GlobalTransactional annotation.

RM (Resource Manager) : Manages branch transaction resources such as database connections. It registers branch transactions with TC, records undo logs, and executes commit/rollback for each branch. The registration is usually performed by Seata’s DataSourceProxy.

Transaction Flow Example

Consider the business scenario: user places an order → inventory is deducted → account balance is deducted. The complete execution flow consists of six steps:

TM starts a global transaction : The order service method is annotated with @GlobalTransactional. TM requests TC to create a global transaction and receives a unique XID.

RM registers branch transactions : Each participating service (inventory, account) uses DataSourceProxy to automatically register a branch transaction with TC and records an undo log.

Local transaction execution : Services execute their SQL statements. The statements succeed but are not committed yet, staying in local transaction state.

TM decides commit or rollback : If the business method completes without exception, TM sends a commit request to TC; otherwise, it sends a rollback request.

TC coordinates all RMs : Based on the global transaction status, TC notifies each RM to either commit or roll back their branch transactions.

Global transaction ends : TC updates the global transaction status to Committed or RolledBack, completing the process.

Code Example

@GlobalTransactional
public void createOrder() {
    orderService.create();
    stockService.deduct();
    accountService.deduct();
}

In this snippet, the @GlobalTransactional annotation triggers TM to start a global transaction, which then coordinates the subsequent branch operations performed by the inventory and account services.