atom feed: Empty Feed or 404?

We have a REST server which ret开发者_如何学运维urns Feed (ATOM) based on the input query. For certain query parameters (valid/invalid) the Feed contains zero entries. For zero entries should an empty feed be returned or 404? Is there a standard way this is handled?

Any pointers will be helpful.

If the query is truly invalid, i.e. it can never return any results by the logic of your webapp, then you should return an error. If there's just nothing to report yet, then an empty feed would be appropriate.