Yesterday, I had the opportunity to play with file API. This API, proposed by Mozilla, allows reading a file content directly from a webpage, that is, without sending it to the server first. User must provide a file, either by drag and dropping it on the page, either with a normal input file (
<input type="file">). So, a web page cannot read a file on the computer without user consent.
Developer mozilla site has a good tutorial about the subject. This allowed me to quickly set up a small demo. A world map is displayed (thanks to OpenLayers library). When a file with geographic informations is dropped on it, the file is read by the web page, and geometries are automatically drawn on the map.
Currently, demo only works with Firefox 3.6 because it's the only web engine to implement this functionality. A bug is opened on webkit bugtracker, but no real progress has been made yet.