set id attribute
        Paramters:
            el -- MessageInterface representing the element
            objid -- ID type, unique id

def set_attribute_id(self, el, objid):
        '''set id attribute
        Paramters:
            el -- MessageInterface representing the element
            objid -- ID type, unique id
        '''
        if self.unique is False:
            el.setAttributeNS(None, 'id', "%s" %objid)