Google Professional Cloud Developer Question 320
Select 3Google Cloud PlatformYou are developing a new version of a REST API on Google Cloud that introduces additional fields to a response without removing or modifying existing ones. Several clients currently depend on the existing structure of the API. Which of the following approaches ensures backward compatibility?
- A
Add new fields to the response and document the changes in the API specification.
- B
Modify existing field names to make them more descriptive.
- C
Introduce versioning in the API and deploy the changes as a new version.
- D
Remove unused fields from the response to optimize payload size.
- E
Ensure that the clients can ignore additional fields they do not use.
Show answer and explanation
Correct answers: A, C, E
Explanation
Backward compatibility ensures that existing clients can continue functioning without modification when changes are made to an API. Adding new fields (without removing or modifying existing ones), documenting the changes, introducing versioning to isolate changes, and ensuring clients can ignore new fields are all techniques to maintain backward compatibility. However, removing fields or modifying existing ones can break existing clients and should be avoided.
- A. Correct.
Adding new fields to the response and documenting the changes ensures that existing clients can continue using the API as long as they ignore fields they do not use. This maintains backward compatibility if implemented correctly.
- B. Incorrect.
Modifying existing field names breaks backward compatibility because existing clients expecting the old field names will fail to operate correctly.
- C. Correct.
Introducing versioning allows you to deploy the changes as a new version of the API while leaving the current version intact, ensuring backward compatibility for existing clients.
- D. Incorrect.
Removing unused fields can break backward compatibility if any existing clients rely on those fields, even if they are considered 'unused' by the server.
- E. Correct.
Ensuring that clients can ignore additional fields they do not use is a key principle for maintaining backward compatibility in APIs, as it allows existing clients to function without changes.