I haven't actually tried this, but this is what I see...
In the meta.json (part of the extension.zip) you will see these settings:
Change service_url to "http:", this is known to prevent Jive from calling the register_url. Additionally you might want to blank out both the register_url and unregister_url values (or maybe even remove the properties completely if Jive doesn't complain).
In the definition.json (part of extension.zip) you will see something like this:
"name": "Sizing App",
The bad news is that the app.xml isn't contained in the extension.zip and must be downloaded from somewhere (AFAIK). You will need to find a place to host this file and update the url property accordingly. Perhaps you could even upload app.xml to your own Jive instance as a public file.
Note: I am assuming that there are no other files outside of your app.xml. If you have additional HTML/CSS/JS files you may want to try to embed all of that content into the single app.xml file.
In theory this should work... but I haven't tried it.
Thank you, Robert.
I'll try. Hope this topic will be helpful for more people.