SI-Designer (Source Integrator Designer) is a designer supporttool for semi- automatic integration of heterogeneoussources schemata (relational, object and semi structuredsources); it has been implemented within the MOMIS projectand it carries out integration following a semantic approachwhich uses intelligent Description Logics-based techniques,clustering techniques and an extended ODMG-ODL language,ODL-I3, to represent schemata, extracted, integratedinformation. Starting from the sources’ ODL-I3 descriptions(local schemata) SI-Designer supports the designer inthe creation of an integrated view of all the sources (globalschema) which is expressed in the same ODL-I3 language.We propose SI-Designer as a tool to build virtual catalogsin the E-Commerce environment.