It's essentially a proprietary proxy + tunnel - on the client, you install their COM object as OPC service, then it goes over tunnel to a server process which t

It's essentially a proprietary proxy + tunnel - on the client, you install their COM object as OPC service, then it goes over tunnel to a server process which talks to actual vendor OPC DCOM library using local COM. Understandable when configuring security can be a big PITA.