> You're asking a remote system to do a job for you, and if that job completes successfully, it's a "Success" in the HTTP world.
But a provided credit card number not existing is not success, it is unambiguously a failure.
HTTP is a transport but its response codes are clearly designed to map somehow to the "business logic" of the thing underneath it. We have to twist ourselves up in knots to map most of our business systems to the set of status codes that make sense for the default HTTP-fronted application (Fields' thesis stuff) but that's what we sign up for when we decide to expose our business services via HTTP. Other transports require different contortions.
But a provided credit card number not existing is not success, it is unambiguously a failure.
HTTP is a transport but its response codes are clearly designed to map somehow to the "business logic" of the thing underneath it. We have to twist ourselves up in knots to map most of our business systems to the set of status codes that make sense for the default HTTP-fronted application (Fields' thesis stuff) but that's what we sign up for when we decide to expose our business services via HTTP. Other transports require different contortions.