Castanet Tunerv3.0

Castanet channels (applications and their data) observe the security of applets while improving on applets in several ways. Although channels are automatically distributed and installed like applets, they appear to users more like applications. Stored on the client disk, channels start quickly, and run smoothly and reliably--whether the computer is connected to a network or not. Channel user interfaces are not constrained by Web page or browser limitations; channels can provide multi-window, multimedia user experiences of the highest quality. Channels can create and maintain persistent data, such as documents and preferences, and can communicate data, such as usage patterns, back to their servers. Running on a client machine, a Castanet tuner cooperates across the Internet or an intranet with a Castanet transmitter running on a server. The result is mirrored channel files on the client: channels that are always complete, current, and self-consistent. Tuners can install new versions of a channel's files while the current version is running; for example, a sports scoreboard channel can receive new scores every few minutes. For maximum efficiency, channels are "differentially" updated: only modified files are sent by transmitters to tuners, and all files are sent in a single TCP connection. Because only a small percentage of a typical channel's files change, updates can be frequent and fast.