There have been and for sure will be some requests on the question How can I read/write/monitor variables from control system XYZ?
In some cases this is realized in writing a device support module for a soft device, in other cases it means teaching the opponent to use the Channel Access protocol of EPICS, or using an intermediate Data Access Layer, or something else.
This section summarizes and collects some existing - mostly external - solutions and trials - mostly internal - to let EPICS talk to others.