var COMMAND_VERIFYSIGN = "actionverificarfirma";
  var Literals = {
    Loading : "verifyLoading",
    Dialog : "verifyDialog",
    FormName : "verifyForm",
    Result : "verifyResult",
    Target:  "upload_target",
    State:   "state",
    Success: "success",
    Error: "error"
  }

  function showLayer(sLayer) {
    var DOMLayer = $(sLayer);
    DOMLayer.style.display = "block";
  }

  function hideLayer(sLayer) {
    var DOMLayer = $(sLayer);
    DOMLayer.style.display = "none";
  }

  function showLoading() {
    showLayer(Literals.Loading);
  }

  function hideLoading() {
    hideLayer(Literals.Loading);
  }

  function showDialog() {
    showLayer(Literals.Dialog);
  }

  function hideDialog() {
    hideLayer(Literals.Dialog);
  }

  function verifySign() {
    var DOMForm = $(Literals.FormName);
    var target  = $(Literals.Target);
    DOMForm.target = target.id;
    DOMForm.action = COMMAND_VERIFYSIGN;
    
    showLoading();
    hideDialog();
    
    Event.observe(target, "load", function(event) {
      var doc = target.contentWindow.document;      
      var DOMResult = document.getElementById(Literals.Result);
                        
      DOMResult.innerHTML = doc.body.innerHTML;
      hideLoading();
      showDialog();
    });
    
    DOMForm.submit();
  }