I have a resources with uri /api/books/122 , if this resource doesn\'t exist at the point where a client sends HTTP Delete for this resource, what is the approp
Yes, it would be 404.
In general it will be a 400 series error if the request is wrong somehow, and a 500 series error if something goes awry on the server.
The response code for a delete call can be any of the following :
DELETE /api/book/122 - The server successfully processed the request, but is not returning any content
204 No ContentDELETE /api/book/122 - Resource does not exist
404 Not FoundDELETE /api/book/122 - Resource already deleted
410 GoneDELETE /api/book/122 - Users does not have permission
403 Forbidden DELETE /api/book/122 - Method Not Allowed
405 Method Not AllowedDELETE /api/book/122 - Conflict (User can resolve the conflict and delete)
409 ConflictIn your case 404 is apt.