In distributed systems, materialized views are used to improve data availability and reduce data transfers. A materialized view is a query whose results are pre-computed from multiple data sources and stored in the database. Defining views over heterogeneous data sources requires the design of a common query language or the conversion of the data sources in the same format. This paper addresses this problem by proposing a model-driven approach for views definition over distributed and heterogeneous data sources which makes use of a high level modeling language.