call to webservice External (non sap) system from SAP CRM

Hi,

I have to make a call to External system from SAP CRM 5.0 system. The external system will provide a sample webservice which SAP will try to initiate

Can you please tell me:

1. What settings/object needs to be maintained in SAP in order to make this call.

2. how I can make a call to this Web-Service from a BADI and pass the values to web service and also capture the returning value.

Please explain in detail

Thanks,

Mike