function headerLogin()
{
  // invoke AJAX:
  new Ajax.Request('/Index',
  {
    method:'post',
    parameters: { __ia: 'login', __login: $('header_login').value, __password: $('header_password').value, no_cache:(new Date()).getTime() },
    evalJS: true,
    onSuccess: function(transport)
    {
      if (transport.getHeader('header-error-login')!=null) showErrorDiv4Element(transport.getHeader('header-error-login'),'header_login');
      else
      {
        window.location.reload();
        // reload whole page, as this fixes all problems encountered, e.g. changed observations or when 
        // only reloading the header and chaning the sessionID for the Update for example
      }
    }
  });
}
function detailLogin()
{
  // request login:
  new Ajax.Request('/Index',
  {
    method:'post',
    parameters: { __ia: 'login', __login: $('detail_login').value, __password: $('detail_password').value, no_cache:(new Date()).getTime() },
    evalJS: true,
    onSuccess: function(transport)
    {
      if (transport.getHeader('header-error-login')!=null) $('login_error').update(transport.getHeader('header-error-login'));
      else _reloadPageAfterLogin();
    }
  });
}
function _reloadPageAfterLogin()
{
  location.href = $("login_redirect_url").value;
}



function logout()
{
  // invoke AJAX:
  new Ajax.Request('/Index',
  {
    method:'get',
    parameters: { __ia: 'logout', no_cache:(new Date()).getTime() },
    evalJS: true,
    onSuccess: function(transport)
    {
      window.location.href = mBaseURL;
      // reload whole page, as this fixes all problems encountered, e.g. changed observations or when 
      // only reloading the header and changing the sessionID for the Update for example
    }
  });
}