The JSON API is mostly a wrapper for the existing XMLRPC v2 API except that it has support for non-administrator accounts baked in. So you can actually build a frontend for OpenX that your non-admin users can use to manage your advertising inventory.
The API interfaces with the same library files, in the same way as the standard interface, so user permissions are maintained.
{
isError: BOOL,
message: STRING (not required),
data: MIXED
}