MSDTC

MSDTC, or Microsoft Distributed Transaction Coordinator, is a Windows service that coordinates distributed transactions across multiple resource managers, such as databases, message queues, and file systems. It implements the two‑phase commit protocol to ensure atomicity across heterogeneous resources. MSDTC can coordinate transactions that span multiple processes and machines, enabling a single transaction to commit or roll back if any participating resource cannot complete.

Operation: When an application starts a distributed transaction, the transaction is promoted to the MSDTC, which communicates with participating resource managers via their transactional interfaces. In the first phase, each resource manager reports readiness to commit. In the second phase, all participants either commit or abort, and MSDTC propagates the result. If any resource manager fails to commit, the transaction is rolled back everywhere.

Typical use cases include coordinating updates to multiple SQL Server databases, or combining a database operation with a transactional message send (for example, MSMQ) within a single logical transaction. MSDTC can be used by legacy COM+/MTS applications as well as by .NET applications through System.Transactions, which can enlist resource managers in a distributed transaction.

Configuration and security: To use MSDTC across machines, enable Network DTC Access in the Component Services administrative tool, configure authentication and authorization, and ensure proper firewall rules for RPC/DCOM traffic and the DTC port range. The MSDTC service (MSDTC.exe) must be running on all participating machines, and clocks should be synchronized for proper timeouts and retries.

History and scope: MSDTC was introduced with Windows 2000-era technologies (as part of MTS/COM+) and has since been integrated with the .NET Framework’s System.Transactions. It remains a central mechanism for coordinating distributed transactions on Windows platforms, though its use requires careful configuration to avoid performance and reliability issues.