private AtomFeed ExecuteFeedRequest(string url, RequestOperation operation, out string eTag)
{
var response = ExecuteRequest(url, operation, MediaType.Atom, MediaType.Xml);
var result = response.Content as AtomFeed;
if (result == null)
{
throw new SDataClientException("Unexpected content: " + response.Content);
}
eTag = response.ETag;
return result;
}