Who called whom in the synchronous chain? Tell about the business process — what calculation, who initiated?

In a synchronous call chain, each subsequent component is usually called by the previous one, forming a sequential execution flow. For example, in a business process of calculating an order price:

• The client initiates a request to create an order.
• The order service calls the pricing service, passing data about products and discounts.
• The pricing service calls the tax service to get current tax rates.
• After receiving the taxes, the pricing service returns the total amount to the order service.
• The order service confirms the order creation and returns the result to the client.

Thus, the initiator is the client, who starts the chain of calls. Each service calls the next to obtain necessary data or perform part of the logic. This ensures sequential execution of business logic, where each step depends on the result of the previous one.

This approach simplifies control and debugging but may be less efficient for long operations, where it is useful to use asynchrony or parallelism.