Effective exchange and sharing of information across supply chains play a key role in business-to-business integration (B2Bi). Web Services enable companies to collaborate closely with their business partners and gain access to needed information and business logic. However, helping small and medium enterprises (SMEs) to participate in B2B collaborations and make use of the advances of the service oriented technologies are challenging tasks. In an effort to bridge the gap between small and big companies, a Web Service-enabled B2B integration approach for SMEs was developed. It provides a feasible and cost-effective solution for SMEs to take part in B2B collaborations by taking advantage of Web servicespsila characteristics and lightweight IT infrastructure for SMEs. In this approach, two mechanisms namely pull and simulated push mechanisms of Web Services are designed. This paper provides a detailed discussion and merits of such a mechanism for enabling B2B collaborations for SMEs.