The only problem with Stuart’s approach is that ClassicUI is basically end of life and that particular HTTP GET call was never really officially supported. Consequently this approach is not guaranteed to work forever. And it kind of sucks to install a whole UI just to allow this one call.
Luckily, back when I was trying to figure out how to do some OAuth stuff, I figured out how to do this using just an http file in $OH_CONF/html.
You will only need to pay attention to the HTML File section. This includes some JavaScript to parse the arguments from the URL and then uses XMLHttpRequest to issue the POST to the OH REST API.
MDAR
(Stuart Hanlon, UK importer of Velbus hardware)
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