How to use Opennebula API in java peogram


I have been tried to install opennebula in my ubuntu 18.04 to use their java API and then manage a cloud infrastructure, but the opennebula-sunstone failed to start.
so, when i tape http://localhost:2633/RPC2 , i recived

Error 405

POST is the only HTTP method this server understands

ABYSS Web Server for XML-RPC For C/C++ version 1.40.0

am i on the right way? can i use now the opennebula API ?

And i want to know how can i execute a program that uses the opennebula API ?
can i use any server such as Tomcat ?
which type of program should i write (e.g., java program pr dynamic program or spring boot program)?