  Ontology-based data integration has been one of the practical methodologies
for heterogeneous legacy database integrated service construction. However, it
is neither efficient nor economical to build the cross-domain ontology on top
of the schemas of each legacy database for the specific integration application
than to reuse the existed ontologies. Then the question lies in whether the
existed ontology is compatible with the cross-domain queries and with all the
legacy systems. It is highly needed an effective criteria to evaluate the
compatibility as it limits the upbound quality of the integrated services. This
paper studies the semantic similarity of schemas from the aspect of properties.
It provides a set of in-depth criteria, namely coverage and flexibility to
evaluate the compatibility among the queries, the schemas and the existing
ontology. The weights of classes are extended to make precise compatibility
computation. The use of such criteria in the practical project verifies the
applicability of our method.
