web services can be decoupled from the Business Object structure by using a XSLT transform from one xml schema (webservices response schema) to IBM BPM(Lombardi) variable schema. The transform can be performed by the OOB System Services for XSLT based transforms.Once you have the transformed XML you can directly create a BO instance using tw.system.serializer.fromXML() method. If the schemas are simple you can code the xslt by hand but if you are dealing with large and complex structures tools like altova mapforce are very handy in generating the xslt using drag and drop kind of gui designing. The benefit of decoupling is that you can alter business objects without changes to web services and vice versa.