private string GetInterviewerInstructionUri(string surveyId, string fileName)
{
var result = new StringBuilder(ConnectionClient.NfieldServerUri.AbsoluteUri);
result.AppendFormat(@"Surveys/{0}/{1}/"
, surveyId, SurveyInterviewerInstructionsControllerName);
if (!string.IsNullOrEmpty(fileName))
result.AppendFormat(@"/{0}", fileName);
return result.ToString();
}