For those you who haven't seen it, yet: MTOM and XOP are now W3C Proposed Recommendations (16 November 2004), so the final may be only few weeks away? SOAP Message Transmission Optimization Mechanism http://www.w3.org/TR/soap12-mtom/ XML-binary Optimized Packaging http://www.w3.org/TR/xop10/ Cheers, T.