about Principal used in new API

hello, i use the new API of WVCM_113. There are some new concepts for me. After reading the example code, i think, with the help of ACL and Principal, i can realize the security function.
But i don’t know, How can a Principal execute a Webdav request to resource, i.e. if I want to read or modify the content of a resource through different Principal with some roles?