CIS

COM Internet Service (CIS) is an HTTP tunneling protocol for DCOM. DCOM uses dynamic ports, which does not play nicely with firewalls. Networking in the real world may also involve IP address aliasing, VPNs etc.

CIS solves these problems. However, it never really caught on and nowadays it’s difficult to find information about. (Got a link?)

Microsoft seems to have repurposed the acronym CIS to mean Center for Internet Security, an unrelated thing, which foils keyword searches.

References