The server-side webapp page can detect that it’s running inside a html dialog by parsing the User Agent string. When this is the case an “Upload from SketchUp” button could appear. The onClick event handler function attached to the button can fire a Ruby callback (from your SketchUp extension) to prepare and send the data to your server.
- EDIT: Actually the mere existence of the
sketchupJavaScript object would be enough to determine the web page was displayed within SketchUp.
But this is only one way to do it. The data gathering interface could also be all client-side and only display the server-side webapp page after a successful upload.
Whatever seems intuitive to the end users is best.
Not meaning to exclude anyone specific nor in any particular order …
Take a look at some of the projects of these programmers:
Generate interactive dashboards and reports from SketchUp models in Microsoft Power BI