While I am trying to figure out how to connect to a Webserver, I will list my findings here. For me this is the first time, it is done in the way mentioned later. That means there will be mistakes in the stuff shown here. So if anyone reads this and has some suggestions for improvement, please let me know!!!
The Webserver has double security. First is to gain access with a X.509 certificate. Second is the use of WSS with Kerberos to encrypt parts of the message sent.
The first thing was to create a Keystore. I have exported the Certificate from the webservice using Firefox. Followed the steps mention in the reference and created the keystore with following commands:
keytool -genkeypair -keyalg RSA -alias [MyKeyStoreName] -keystore [MyKeyStore] -storepass [MyPassword] -keysize 2048
keytool -import -alias [MyCertificateName] -file [MyCertificate] -keystore [MyKeyStore]