John McDowall believes that being able to use WSDL to specify strongly typed message properties is what separates REST from web services. I disagree. First, you can use WSDL for describing REST-based services; secondly, SOAP and REST are not in conflict; and third, IMO neither WS-Addressing nor WS-ReliableMessaging need to be in conflict with REST principles either, if used accordingly. Lastly, if you use WSA and WS-RM, message properties are not specified in WSDL; rather, the communication characteristics are attached via policy.