Using HTTP status codes to reflect success/failure of Web service request?

I'm implementing a Web ser开发者_开发百科vice that returns a JSON-encoded payload. If the service call fails -- say, due to invalid parameters -- a JSON-encoded error is returned. I'm unsure, however, what HTTP status code should be returned in that situation.

On one hand, it seems like HTTP status codes are for HTTP: even though an application error is being returned, the HTTP transfer itself was successful, suggesting a 200 OK response.

On the other hand, a RESTful approach would seem to suggest that if the caller is attempting to post to a resource, and the JSON parameters of the request are invalid somehow, that a 400 Bad Request is appropriate.

I'm using Prototype on the client side, which has a nice mechanism for automatically dispatching to different callbacks based on HTTP status code (onSuccess and onFailure), so I'm tempted to use status codes to indicate service success or failure, but I'd be interested to hear if anyone has opinions or experience with common practice in this matter.

Thanks!

http status code are just for indicating the status of the application response. and as you said, if json parameters as somehow invalid, a 400 status code is an appropriate answer.

so yes, it is a really good idea to use http status code. de plus, status code are then easy to understand as they don't change from an application (web services) to another

You should definitely use the proper status codes since they are exactly for this purpose, not to indicate the status of the HTTP request itself. By this way you can redirect the response to the appropriate function/branch before parsing it which will lead to a much tidier code in the client side.