フリー問題

問題文

A mobile client calls a service over HTTP and needs to retry a failed call safely without creating a duplicate record. Which pair of properties should the service give that operation?

選択肢

1. The operation must be stateless so that a repeated call leaves the same socket, and the body should carry a compressed document whose frame the client can read without downloading the specification.
2. The operation must be idempotent so that a repeated call leaves the same outcome, and the body should carry a structured document whose fields the client can read without downloading the specification.
3. The operation must be stateless so that a repeated call leaves the same socket, and the body should carry a structured document whose fields the client can read without downloading the specification.
4. The operation must be idempotent so that a repeated call leaves the same outcome, and the body should carry a compressed document whose frame the client can read without downloading the specification.