In REST, what could happen if two POST requests are made to the same resource URL?

• A. Only one request will succeed
• B. Both requests will return a 400 error
• C. They may update different parts of the object
• D. Only the first request will be executed

Answer: (C)

When two POST requests are made to the same resource URL, the behavior can vary based on the server’s implementation and the nature of the resource being manipulated. The correct choice indicates that the requests may update different parts of the object. This is plausible in scenarios where the service is designed to handle concurrent modifications gracefully.

In RESTful practices, a POST request typically indicates a request to create a new resource. However, if the server logic allows modifying an existing resource or if the two requests contain different data intended to update specific fields, they can coexist without necessarily overriding each other, depending on how the backend is implemented.

For example, if each POST request contains data that refers to different attributes of the same resource, the server might be designed to apply these updates in a way that both changes are stored together. This optimistic concurrency model allows multiple clients to interact with the same resource more flexibly, as long as appropriate conflict resolution mechanisms are in place.

Understanding potential outcomes helps in designing robust APIs. This ability to handle concurrent requests enhances usability and maintains data consistency, crucial aspects when dealing with web services and RESTful APIs.