This paper deals with integration of XML heterogeneous information sources into an information server according to an approach combining mediation and data warehousing. A schema, or ontology, is used to access to the external sources and also to the local data. We propose a unified method based on such an ontology able to achieve the two kinds of integration. Our contribution is twofold. First, we propose techniques to automate the generation of mappings between the ontology and a new source. Second, we present an approach to automate the construction of wrappers starting from the description of the abstract content of a source and ending by data extraction. Experiments on real data in the tourism domain have been achieved. Analysis and comments of the results are given.