Well you could use SSL to connect from ODWEK to CMOD Server if you're aren't already. You are correct though, it is TCP/IP. I would add, there may be many definitions of "secure". Keep in mind, you are typically talking about a connection from two internal servers, not WEB facing environments. In addition, you can lock down this down in other ways as well. For example, only opening specific ports through a firewall.
The point is, there is lot more to consider then just how ODWEK communicates with the CMOD server.
-RR