public HttpResponseMessage <List <string> > ListImages() { var databaseImagesNames = new List <string>(); var allImages = satelliteImageRepository.GetImagesUrlPath(); foreach (var i in allImages) { var urlParts = i.Split('/'); var last = urlParts.Last(); databaseImagesNames.Add(last); } List <string> serverImagesNames = XmlParserSatelliteImages.ListImages(); List <string> imagesToHide = serverImagesNames.Intersect(databaseImagesNames).ToList(); List <string> imagesToShow = serverImagesNames.Except(imagesToHide).ToList(); return(new HttpResponseMessage <List <string> >(imagesToShow) { StatusCode = HttpStatusCode.OK }); }