private void login(String username, String password, URL url) throws ResourceException {
if (!isValid()) {
LoginResult loginResult = null;
sfSoap = null;
sfService = null;
co = new CallOptions();
// This value identifies Teiid as a SF certified solution.
// It was provided by SF and should not be changed.
co.setClient("RedHat/MetaMatrix/"); //$NON-NLS-1$
if(url == null) {