urlValidator.validate(operation);
String urlSpec = operation.get(URL).asString();
try {
URL url = new URL(urlSpec);
return url.openStream();
} catch (MalformedURLException e) {
throw new RuntimeException(urlSpec + " is not a valid URL", e);
} catch (IOException e) {
throw new RuntimeException("Error obtaining input stream from URL " + urlSpec, e);
}