Webservices and BPM

Hi all,

How a normal BPM process in Netweaver is Related to Web services. Is BPM process internally using SOAP Webservice? because i see a webservice model in webdynpro component using a BPM process component.

is the knowledge of webservices is required for doing a project in BPM with Webdynpro Java.

I think its a basic question.Please help on this .

regards

Deva