Additional common/important HTTP Response Codes

[inadarei]

200 OK: Success!

201 Created: a common return code for a successful HTTP POST (or PUT in idempotent creations)

202 Accepted: request was accepted, but has not fully been processed, yet. A common code to return for asynchronous calls.

304 Not Modified: There was no new data to return (think: cache). <-- This is very important!

400 Bad Request: Invalid Request. Error message will be returned to provide further details.

401 Unauthorized: Authentication credentials were missing or incorrect.

403 Forbidden: Valid request that was refused. Attempt to access a resource that the client does not have permission to. Error message will be returned to provide further details.

404 Not Found: The URL requested is invalid or the resource requested, such as a document or a user, does not exists.

406 Not Acceptable: Returned when parameters passed are correct in theory and individually, but when combined can not be satisfied because the combination makes no sense (e.g. cart_id from one user is used with a user_id from another user). If possible, an error message will be returned to provide further details.

500 Internal Server Error: Something went horribly wrong and we were not smart enough to provide more details :) Hopefully a very rare response code.

503 Service Unavailable: Servers are offline for maintenance or went down under load (oops).

[mikestowe]

+1 - submitted PR for this (minus 406 and 503 for brevity)