Product data integration is an essential issue for many e-commerce interoperable business systems. Core to this issue is how to maintain semantic consistency between heterogeneous product data that are semantically different in structure, concept and context. To resolve the issue, this paper proposes a transparent collaborative integration approach, which is built on a layered framework of messaging, structure, concept and collaboration. The key to this framework is three collaboration engines, which resolves semantic consistency issues between millions of contextual vocabularies of SMEs.