function wsHttpPost(url, callback, formData) 
  {
    var xhr = new XMLHttpRequest();
    xhr.open('POST', url, true);
    xhr.withCredentials = true; 
    xhr.onload = function () {};
    xhr.onreadystatechange = function () {
      if (this.readyState === 4 && this.status == 200) {
        callback(this);
      } 
    };
    xhr.upload.onprogress = function (event) {
      //TODO show the progress
    };
    xhr.send(formData);
  }