Nowadays XML-based data integration systems are accepted as data service providers on the web. In order to make such a data integration system fully equipped with data manipulation capabilities, programming frameworks which support update at the integration level are being developed. When the user is permitted to submit updates, it is necessary to establish the best possible data consistency in the whole data integration system. To that extend, we present an approach based on an XQuery trigger service. We define an XQuery trigger model together with its semantics. We report on the integration of the XQuery trigger service into the overall architecture and discuss details of the execution model. Experiments show that data consistency is enforced easily, efficiently and conveniently at the global level.