Difference between updateInterval in http.cfg and refreshintervalinmilliseconds in *.items in HTTP Binding?

I’m new to HTTP Binding. I got it working.
I have added url to /services/http.cfg file with myservice.updateInterval=900000 (15 minutes).
But there is also refreshintervalinmilliseconds parameter thtat can be used when defining items in *.items file.

What is the difference between those two properties? Which is more important? Which overrides whitch?

Tells the HTTP binding how often to fetch data from the URL and save it in cache.

For a cache-linked Item, tells it how often to go and get data from the cache.

For non-cached Item, i.e. a direct URL is given, tells it how often to go and fetch data from the URL.

If I omit refreshintervalinmilliseconds then my data will update at the moment cache is updated?
Or will cache not update on itself if there is no polling from items file?

So far as I know, you cannot omit it. If you could, then it would never update the Item - unless maybe there is some default setting. If you don’t ask for an Item update, you won’t get one.

The cache proceeds independently according to what you set in http.cfg
It doesn’t care if you have many or none Items linked to it.

You could just try this stuff and find our.