In an attempt to help people better understand how a technology like Java DB can keep Web applications running even when no Internet connection is present, Sun's "Mr. JavaDB" Francois Orsini has posted a bit of a primer that talks about persistence and Java DB can faclitate something called "Local AJAX." Writes Orsini:
The embedded Java DB demo which showcases local and secure storage in the web brower is not just enriching the browser but principally enabling web applications to operate offline / disconnected.....A local AJAX controller can handle requests and serve responses in XML format the same way AJAX currently does...We're talking about offline data management capability at the AJAX level (Local AJAX). Now how does this work from a 14,000 feet view? well, there is no magic and it is fairly straightforward to understand - a (local) client service(s) controller can satisfy AJAX type requests and return data from a local and embedded database system (Java DB) for instance. In the demo I wrote, the data being returned would purely be database rows in XML format, the requests can be canned SQL queries or pure SQL submitted via AJAX, locally....There [are] absolutely no changes with the DHTML and AJAX request handling syntax(es) - hence the learning curve is slim and additional code changes will be homogeneous with the rest of your new or existing webapps.
Orsini has publicly demo'd a Java DB-powered app. But to see whether or not there is real promise for Web applications unplugged, we need something more real world. So, over on the Mashup Camp Web site where Berkman Center fellow David Isenberg started a trend by posting Mashups We Want, I've posted a new pages for AJAX Apps We Want and on it, I've requested some offline capabilities for Wordpress and MediaWiki. Any takers?