HttpWebRequest.GetResponse() - what specific status codes cause an exception to be thrown?

Question

I've hunted around for some definitive documentation on this but haven't had much luck finding any.

Basically - the question is - for which HTTP Status codes coming back from the server will HttpWebRequest.GetResponse() generate a WebException after doing something like say, a POST?

Specifically - will it generate a WebException for anything other than status 200 OK? Or will it only generate a WebException for say, 400, 404, and 500 (for the sake of argument).

I want to know since, the server I'm communicating with defines anything other than HTTP 200 OK coming back as an error condition - and the key is, can I rely on a WebException being generated for anything other than 200? (I've currently written my code so that it'll actually check the return status code everytime to ensure it's 200 OK and if it's not, take appropriate action - but it's alot of duplication between that, and the catch block for a WebException, and I'm hoping to clean it up...)

Any relevant links to documentation would be most appreciated.

Thanks!

Answer 1

The WebException system is seperate system from the HTTP error system. This is mainly because the HTTP errors are returned by the browser or client and the WebException is thrown by the server while building your page. By the time an HTTP error is found the page is sent to the client and you won't know about it.

Answer 2

I think it will, but it sounds like a risky assumption to make. For one thing, the MSDN docs make it clear that GetResponse will throw exceptions other than just WebException. However, I can say for definite from experience that a "304 Not-Modified" response will be thrown as a WebException.

All this talk is giving off a whiffy Code Smell; don't use exceptions to control the flow of execution. You would be better off handling exceptions appropriately, then explicitly checking the StatusCode property for your allowable values.

Answer 3

Ended up doing an explicit check after the response & catching and checking WebExceptions; results in some duplicated code but there's no definitive answer on whether a WebException will ALWAYS occur if the status is NOT 200.