I just followed the below url to invoke osb from bpel(11g).
1. For the 1st step I confused, To get a wsdl,I created one bpel process which is just taking the request and doing nothing and send back the response.
2. Now I use this wsdl(step1,bpel process wsdl) to create the proxy servcie on osb.
Then I follow the next steps.However while I test my original bpel servcie(which is calling the proxy wsdl),its displaying me the response of the o/p of the bpel servcie(which I created for proxy).Its not invoking the OSB.