app with standalone gui and web interface

[Daniel Nogradi]

What would the simplest way to make an application that has both a web
interface and runs from behind a web server but also can be used as a
standalone app with a gui? More precisely is it possible to avoid
creating an html/xml/whatever based web interface for the web version
and separately creating a gui (wxpython for example) for the
standalone version and instead create a graphical frontend at once
that can be used for both?