static new ThreadLocal<Bool> doPost_silently;
static new ThreadLocal<Long> doPost_timeout;
static new ThreadLocal<SS> doPost_extraHeaders;

sS doPost(S url, Map urlParameters) {
  ret doPost(urlParameters, url);
}

sS doPost(Map urlParameters, S url) {
  ret doPost(makePostData(urlParameters), url);
}

static String doPost(S urlParameters, String url) ctex {
  URL _url = new URL(url);
  ping();
  return doPost(urlParameters, _url.openConnection(), _url);
}

static String doPost(S urlParameters, URLConnection conn, URL url) ctex {
  bool silently = isTrue(optParam(doPost_silently));
  Long timeout = optParam(doPost_timeout);
  SS extraHeaders = optPar(doPost_extraHeaders);
  setHeaders(conn);
  for (S key : keys(extraHeaders)) {
    ifdef doPost_debug
      print("doPost sending header: " + key + " = " + extraHeaders.get(key));
    endifdef
    conn.setRequestProperty(key, extraHeaders.get(key));
  }

  int l = lUtf8(urlParameters);
  if (!silently)
    print("Sending POST request: " + hideCredentials(url) + " (" + l + " bytes)");
      
  // connect and do POST
  if (timeout != null) setURLConnectionTimeouts(conn, timeout);
  cast conn to HttpURLConnection;
  conn.setRequestMethod("POST");
  conn.setDoOutput(true);
  conn.setFixedLengthStreamingMode(l);
  //conn.setRequestProperty("Content-Length", str(l));

  OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
  writer.write(urlParameters);
  writer.flush();

  String contents = loadPage_utf8(conn, url, false);
  writer.close();
  return contents;
}