Application architecture

The following is the application architecture for the vacation rental application:

Here, you have a client application (Web app) that makes a request to the API gateway. A customer trying to book a vacation makes this request from the client application.

The following events take place after the initial call:

• The API Gateway initializes a Step function.
• The Step function fires an event to call another Lambda function that tries to book a hotel room. It then updates the Fauna database and marks the hotel as booked.
• The Step function fires another Lambda function to book with an available airline. If successful, it updates the database again.
• If the second lambda (booking with the airline) fails, it cancels the hotel booking and reverts the changes in the database.
• The client application listens to the database changes in real-time using Stream API. Therefore, the UI can instantly reflect all of the changes.

In the next section, you will set up your project.