Hi Ewan,

before performing a deeper check,
I notice that a file path is used in "createEngine".
This is not supported, as only an http URL is supported.
Note that GI supports and perhaps sometimes requires that you use local filesystem URLs, but Lightstreamer doesn't.
This is because, in a Lightstreamer-enabled front-end, the front-end pages need to communicate with pages coming from Lightstreamer Server and the latter cannot be from local filesystem URLs. Hence, due to the security restrictions imposed by the browsers, the former pages cannot be from local filesystem URLs too.

Dario