The Publisher transfers the files atomically, so that any network or computer problems do not result in a malformed channel on a Transmitter. Channels can be published interactively with the Publisher's graphical user interface, or programmatically with a script that invokes the Publisher from a command. To revise a channel a developer modifies the relevant files in the channel's base directory and then publishes the channel again. Transmitters accept published channels on the fly. If a Transmitter receives a new version of a channel at the moment when it is transmitting the old version, it continues to serve the old version to Tuners that are already connected, and serves the new version to new Tuner connections.
Transmitters automatically garbage collect obsolete channel files.
A Transmitter runs on a dedicated network port. A Castanet Gateway makes a Transmitter appear to run on the same host and port as a Netscape or Microsoft HTTP servers. In addition to making a Transmitter work with a firewalls that is configured for an HTTP server, a Gateway provides a measure of flexibility. Proxies A Castanet Proxy provides a channel file cache for a collection of Tuners, typically those on a local area network. Like an HTTP proxy, a Castanet Proxy conserves network bandwidth and improves responsiveness.