IF_HTTP_CLIENT to create SOAP messages

I need to communicate with a webservice which publishes a WSDL, in the WSDL <extension> tags are present, ABAP presently does not support this tag and hence I am thinking of writing an ABAP program that creates and sends SOAP messages directly to the web-service

Are there any examples available which uses the IF_HTTP_CLIENT to create and send SOAP messages to a webservice. If there are any code samples could anyone please send me the details.