12.3 About the Sample TCC Application

Let's use the sample TCC application that's available in the installation bundle to understand how microservices and MicroTx interact with each other in a TCC transaction.

The sample application uses the TCC transaction protocol and MicroTx to coordinate the transactions. The MicroTx libraries are already integrated with the sample application code.

The sample TCC application implements a scenario where the travel agent microservice books a trip, flight booking service books a flight, and the hotel booking microservice books a hotel. The travel agent service accesses both the flight and hotel booking services. When a customer books a flight and a hotel, the booking is reserved until either the customer completes the payment and confirms the booking. In case of any failure, the reserved resources are canceled and the resources are returned back to the inventory.

The following figure shows a sample TCC application, which contains several microservices, to demonstrate how you can use MicroTx to manage TCC transactions.

The sample TCC application consists of the following microservices:

• MicroTx (TCC Coordinator)
• Travel Agent service is the transaction initiator service, where the TCC transaction starts. It provides APIs to book and cancel a hotel room and a flight ticket. While booking a trip, this service calls the flight booking and hotel booking services. It also sends the confirm or cancel call to the transaction participant services to finalize the transaction.
• Hotel Booking service participates in the transactions, so it is also called a transaction participant service. It provides APIs to confirm and cancel a hotel room booking.
• Flight Booking service participates in the transactions, so it is also called a transaction participant service. It provides APIs to confirm and cancel a flight ticket booking.

The code for the TCC sample application is available in the tcc folder in the microtx-samples GitHub repository. The sample TCC application code is available in Node.js and Java. When you run the sample application, build all the three sample microservices of either Node.js or Java. Don't try to run the Travel Agent service in Java with Hotel Booking service in Node.js.