Understanding Seata: How Distributed Transactions Work in Spring Cloud Alibaba

What is Seata?

Seata is a distributed transaction solution developed by Alibaba and a core component of Spring Cloud Alibaba, used to solve consistency problems in distributed transactions.

Purpose of Seata

Seata’s main purpose is to address distributed transaction issues in microservice architectures. While monolithic applications rely on a single database transaction to guarantee data consistency, distributed systems involve multiple services and databases, requiring a coordination mechanism that Seata provides.

Core Components

Seata’s transaction management consists of three key roles:

TC (Transaction Coordinator) : coordinates and manages global transactions, creates, commits, rolls back, and tracks the status of branch transactions.

TM (Transaction Manager) : controls the lifecycle of global transactions, initiates begin/commit/rollback requests to the TC, and handles TC responses.

RM (Resource Manager) : manages the execution and state of branch transactions, registers branches with the TC, and performs local commit or rollback on resources such as databases or message queues.

Through the interaction of TC, TM, and RM, Seata ensures consistency and reliability of distributed transactions.

Workflow

The Seata transaction workflow proceeds as follows:

Application service sends a global transaction request to TM.

TM generates a global transaction ID and requests TC to create the transaction.

TC creates the global transaction and notifies each RM to register branch transactions.

Application service executes its local transaction and reports the outcome to TM.

When the global transaction is to be committed or rolled back, TM sends the corresponding request to TC.

TC receives the request and instructs each RM to perform the appropriate operation.

Each RM executes the local commit or rollback.

After all branch transactions have completed, the global transaction ends.

This process guarantees atomicity of the global transaction and consistency of all participating branches.