I was considering some mobile application development and was debating which UI library to use. Some thinking came up with the idea of using the browser as the UI with a local HTTP server. This is really suitable for creating PC local applications rather than mobile apps at this time but more powerful mobile phones may change this.
Browser as UI
With modern browsers and straightorward applications, a perfectly good UI can be built. It is not really possible to create a very complex UI but I claim that most applications do not need a very complex UI - just how dynamic and immersive does a PIM application need to be?
Applications such as Gmail and online office packages demonstrate what can be done.
HTTP server accessing local functions
Using an HTTP server for the 'back-end' functionality means that any language can be used - there really is no need for anything in common with the UI. My personal preference is Python so I am going to experiment with Django.
Using HTTP as the interface can be seen as overkill or inefficient. Rather than reading data directly from the UI and modifying it directly, everything has to be serialised and transferred over an internal socket. This is true but the overhead is probably negligible compared with the actual application functionality. The real queston is whether it provides a convenient programming environment.
Most web development is concerned with preventing insecure access but if the local HTTP server is the application engine then it needs full access to the local machine - not really a problem.
The real issue is deployment of the server - no normal user is going to install and configure Apache and MySQL just for one application. The good news is that the server does not need to be scaleable as it will only be serving one user. This means that lighter-weight servers such as Django's development server or one custom-built from Python's simple HTTP server classes can be adequate.