Have you had experience implementing distributed transactions in your projects?

Yes, experience with implementing distributed transactions was in projects where it was necessary to ensure data consistency across multiple services or databases.

Distributed transactions are complex due to the need to maintain atomicity and consistency in a distributed system. Common patterns include:

• Two-Phase Commit (2PC) — a classic protocol where the coordinator first asks all participants to prepare for commit, then either confirms the commit or rolls back.
• Saga Pattern — breaks a transaction into a series of local transactions with compensating operations for rollback in case of errors.

In Java, you can manage distributed transactions using JTA (Java Transaction API) and corresponding transaction managers.

Example of using JTA with UserTransaction:

UserTransaction utx = (UserTransaction)new InitialContext().lookup("java:comp/UserTransaction");
utx.begin();
try {
    // operations with different resources
    utx.commit();
} catch (Exception e) {
    utx.rollback();
}

In real systems, Saga is often chosen due to its greater resilience and scalability compared to 2PC.