The following table describes the HTTP status codes returned by the URN Resolver Service and their meanings.

200 – Found

The URN was successfully resolved to a structure. The response body contains the resolved structure.

204 – No Content

The URN provided was syntactically valid but could not be resolved to a structure from any registered web service.

302 – Redirect

The URN exists at a known URL, but the URN Resolver Service was unable to obtain the structure. This may happen if the target service blocks the request or if the request times out.

In this case, the Resolver responds with 302 and includes a Location header with the URL of the structure on the target web service. A client application may follow this URL directly to resolve the structure.

304 – Not Modified

The client sent a cache header. The server indicates that no more recent changes are available.

405 – Unsupported Method

The HTTP method used is not supported. For example, sending an HTTP POST or DELETE request will result in this status. See Supported Methods.

406 – Unknown Format

The requested response format is not supported. See Supported Formats.

Note: Accept Headers are typically passed by web browsers which are not SDMX formats, e.g. text/html,application/xhtml+xml. For this reason, only headers starting with application/vnd are checked against known types with other headers ignored if not supported.

422 – Invalid Request

The request was missing a URN, or the URN provided was not syntactically valid. See URN Syntax.

504 – Gateway Timeout

The request took too long to process and has timed out. In this situation, retrying may resolve the issue.