Understanding Distributed Transactions: Theory, Models, and .NET Solutions

Distributed transactions are a technical challenge in enterprise integration and microservice architectures; this article introduces the concept, starting from database transactions and their ACID properties.

It explains how databases ensure consistency after power loss using write‑ahead logs, using SQL Server as an example.

The article then discusses the CAP theorem, its three properties (Consistency, Availability, Partition tolerance), and how it influences design choices in distributed systems.

It introduces the BASE theory (Basically Available, Soft state, Eventually consistent) as an extension of CAP.

Various distributed transaction solutions are presented:

Two‑phase commit (2PC) with XA protocol, its implementation in .NET via TransactionScope and DTC, advantages and drawbacks.

Compensating transaction (TCC) with Try‑Confirm‑Cancel phases, example of money transfer, pros and cons.

Local message table (asynchronous assurance) pattern, describing producer and consumer handling and its alignment with BASE.

Message‑queue transactional messages (e.g., RocketMQ) and their workflow.

Saga transaction model, its workflow of short local transactions with compensation, and a Java code example.

Finally, the author mentions a .NET open‑source distributed transaction framework named CAP, which provides a visual dashboard, supports multiple databases and message queues, and integrates with Consul for service discovery.

SagaBuilder saga = SagaBuilder.newSaga("trip")
        .activity("Reserve car", ReserveCarAdapter.class)
        .compensationActivity("Cancel car", CancelCarAdapter.class)
        .activity("Book hotel", BookHotelAdapter.class)
        .compensationActivity("Cancel hotel", CancelHotelAdapter.class)
        .activity("Book flight", BookFlightAdapter.class)
        .compensationActivity("Cancel flight", CancelFlightAdapter.class)
        .end()
        .triggerCompensationOnAnyError();

camunda.getRepositoryService().createDeployment()
        .addModelInstance(saga.getModel())
        .deploy();