code: function (onDone) {
  		
  	l_validateUID();	
  	var uid = ++l_states['uid_count'];	
  	
  	// store back to DB
      // check existing users
  	SR.DB.setData(SR.Settings.DB_NAME_SYSTEM, l_states, 
  				  	// success
  				  	function (data) {
  						LOG.warn('uid generated: ' + uid);
  						onDone(uid);
  				  	},
  				  	// fail
  				  	function () {
  						LOG.error('uid generation failed with DB');
  						onDone(undefined);
  				  	});	
  }
docs: generate a next unique ID for user TODO: get it from memory