Can we create custom HTTP Status codes?

Question

I have a REST and WCF service and want to send a custom status code based on the operation.

For example when some validation fails then I want to send HTTP 444 and when authorization fails I want to send HTTP 455

The question is how do we have it validated for both SOAP and REST web services.

On the client how does the error code act because when you send an HTTP 400/500 from a WCF Service (using SOAP) an exception is thrown on the client showing the status code?

Now if I send a new custom status code how does the client handle this?

Answer 1

Yes, as long as you respect the class -- that is, 2xx for success, 4xx for Client error, etc. So you can return custom 4XX error codes (preferably those that are unassigned) for your own application's error conditions.

To quote from [RFC 2616][1]:

"HTTP status codes are extensible. HTTP applications are not required to understand the meaning of all registered status codes, though such understanding is obviously desirable. However, applications MUST understand the class of any status code, as indicated by the first digit, and treat any unrecognized response as being equivalent to the x00 status code of that class, with the exception that an unrecognized response MUST NOT be cached. For example, if an unrecognized status code of 431 is received by the client, it can safely assume that there was something wrong with its request and treat the response as if it had received a 400 status code."

Class'

• 1xx: Informational - Request received, continuing process

• 2xx: Success - The action was successfully received, understood, and accepted

• 3xx: Redirection - Further action must be taken in order to complete the request

• 4xx: Client Error - The request contains bad syntax or cannot be fulfilled

• 5xx: Server Error - The server failed to fulfill an apparently valid request [1]:

https://www.rfc-editor.org/rfc/rfc2616#section-6.1.1

Answer 2

I recommend against creating your own HTTP status codes, when applicable codes already exist for the things that you want to do in your example.

• Unprocessable failure: Status 422
• Authorization failure: Status 403

From https://www.rfc-editor.org/rfc/rfc4918#section-11.2:

The 422 [Unprocessable Entity] status code means the server understands the content type of the request entity (hence a 415 [Unsupported Media Type] status code is inappropriate), and the syntax of the request entity is correct (thus a 400 [Bad Request] status code is inappropriate) but was unable to process the contained instructions. For example, this error condition may occur if an XML request body contains well-formed (i.e., syntactically correct), but semantically erroneous, XML instructions.

It can be argued that "unable to process" could be due to a validation error.