BrlAPI: Simple, Portable, Concurrent, Application-level Control of Braille Terminals

Screen readers can drive braille devices for allowing visually impaired users to access computer environments, by providing them the same information as sighted users. But in some cases, this view is not easy to use on a braille device. In such cases, it would be much more useful to let applications provide their own braille feedback, specially adapted to visually impaired users. Such applications would then need the ability to output braille ; however, allowing both screen readers and applications access a wide panel of braille devices is not a trivial task. We present an abstraction layer that applications may use to communicate with braille devices. They do not need to deal with the specificities of each device, but can do so if necessary. We show how several applications can communicate with one braille device concurrently, with BrlAPI making sensible choices about which application eventually gets access to the device. The description of a widely used implementation of BrlAPI is included.