Yes, it is possible.
Please follow the following steps:
1. Connect user to AppWarpS2 server
2. On successfully connection, call joinRoom API
3. If joinRoom fails then call createTurnRoom API
4. In onCreateRoomDone callback, call joinRoom API if room created successfully
This way user will be joining a room if available on the server otherwise he will create and join.
Let me know if you have any further queries.