Which URLs are provided by the server for the client to invoke? What data do these URLs provide? For example, a URL can provide layers and directories in the cloud for clients to retrieve and use to synchronize local layers and directories
The ownCloud client authorizes via oauth and sends WebDAV commands to the server. You’ll find example commands at Accessing ownCloud Files Using WebDAV :: ownCloud Documentation
When you want to go more into detail I’d recommend to use a network analysis program such as wireshark with an unencrypted http connection (to e.g. localhost) where you can follow the single commands the client is sending.