Can you explain what is meant by a distributed transaction and how it works?

A distributed transaction is a transaction that spans multiple independent resources or systems (such as databases, message queues) located on different servers or nodes.

The main goal is to ensure atomicity: either all changes in all systems are committed or all are rolled back, to maintain data integrity.

How it works:

• It uses the two-phase commit protocol (2PC):

  1. Prepare phase: the transaction coordinator asks all participants if they are ready to commit.
  2. Commit/rollback phase: if all participants are ready, the coordinator sends a commit command; otherwise, it sends a rollback.

• In Java, distributed transactions are often managed using JTA (Java Transaction API), which allows working with multiple resources within a single transaction.

Example: if you have two databases and need to update data in both, a distributed transaction guarantees that the changes are consistent.