I'm currently in Santa Clara skilling up on OEG, which can secure access to your services etc. from the outside world. It works in conjunction with WSM. Think of it as taking care of security in the DMZ, working in concert with WSM which takes care of the last mile security.
To quote from OTN -
Oracle Enterprise Gateway provides DMZ-class security and a comprehensive threat defense system at the service perimeter to SOA and Cloud environments, thus providing critical protection needed between un-trusted and trusted zones.
A very compelling addition to our stack -
So I strongly suggest you check out the many resources available on OTN -