To create an order, a client application must send requests to create an order entry, update inventory, and send a transaction to a payment gateway. What is the best way to streamline the client's requests to the backend services?

The best approach to streamline the client's requests to backend services is to create an API gateway called "order" that acts as a facade and handles all the backend API invocations. This method provides several advantages that enhance the efficiency and organization of service calls.

By using an API gateway, all requests from the client application can be funneled through a single interface. This not only simplifies the client code but also allows for more efficient handling of multiple backend service calls. The API gateway can handle the orchestration of the requests to create an order entry, update inventory, and communicate with the payment gateway in a coordinated manner. This aggregation reduces the complexity of managing multiple requests and enables better performance through methods like request batching or parallel processing as needed.

Additionally, the API gateway can implement cross-cutting concerns such as authentication, authorization, and logging centrally, which relieves the backend services from needing to manage these concerns individually. This leads to cleaner, more maintainable code on both the client and server sides.

This solution stands out as a comprehensive approach that not only addresses the immediate need for streamlined interaction with backend services but also positions the architecture for scalability and manageability in the face of future changes or expansions in functionality.