I have develop a JS webapp that call a arcgis services by web adaptor. The AGS is deploy into a back end server and web adaptor into a front end server and web app is deploy into a separate web server with local ArcGIS JS API. Now i have some client that are into a VPN to see only these 3 server but this client not have a internet connection, so does not load arcgis basemap by AGOL. It's possible to load the basemap using a proxy or reverse proxy if the client user not have internet connection? There is some example?
I think the proxy usually just redirects basemap requests through the proxy. However the basemap tile request is still made through the client (i.e. the web server that hosts the proxy does not make the request to return to the client). I would say test it out on something simple to see.
Alternatively, it may be worth looking at this library that Esri have on their GitHub account.
In their own words:
In particular, look at the advanced map tiles and .tpk file options.
If the area that needs to be covered isn't all that big, the tile package may not take up much space. And because they are stored locally, they are extremely quick to load.
You could of course host basemaps on the AGS if necessary.