SOAP 1.2 Part 3: One-Way MEP
http://www.w3.org/TR/2006/WD-soap12-part3-20061219/
http://www.w3.org/TR/2006/soap12-part2/
http://www.w3.org/2000/xp/Group/

The XML Protocol Working Group has released the First Public Working Draft of “SOAP 1.2 Part 3: One-Way MEP.” Where SOAP Version 1.2 Part 2 provides a request-response Message Exchange Pattern (MEP) and a response-only MEP, the new Part 3 Working Draft provides a one-way MEP.