Torrenta v0.4.1

Updatable torrents

An updatable torrent (BEP 46) is a name in the DHT, signed by a key its publisher holds, that points at the current version of a torrent. Its link does not change when the content does: a dataset, a distribution or a collection can grow, and whoever follows the link gets each new version.

Following one

An updatable link looks like magnet:?xs=urn:btpk:<key>&s=<name>. It is taken wherever a magnet is: typed or pasted, opened from a browser, given on the command line, a line in a watch folder’s .magnet file, an RSS article or a search result. Torrenta looks the name up in the DHT and adds the version it points at, through the Add dialog as usual.

From then on, Torrenta looks for a newer version on a schedule:

  • Settings → Adding torrents → Look for newer versions every (6 hours by default; 0 never looks).
  • A newer version is added into the same folder, filed under the same category and tags. Its files that did not change are linked from the old version rather than downloaded again, so an update costs only what changed.
  • Once the new version is complete, the old one is no longer followed. With Remove the old version once the new one is complete on, it also leaves the list; its files stay on disk either way, since the new version may share them.

Settings → Automation can run a program or notify when a new version is added (“A newer version of … was added”).

Publishing one

In the Create Torrent dialog, tick Publish as updatable and give the key a name (letters, digits, dots, dashes and underscores). Create makes the key, seeds the torrent and puts its link in the DHT. The dialog shows the updatable link: that is what others follow, and what you give out instead of a magnet.

On a published torrent:

  • Torrent → New Version… opens the Create dialog for the next version under the same key. Whoever follows the link gets it the next time they look.
  • Torrent → Copy Updatable Link gives the link again.

Both are in the palette too, and only for the current version of something you published.

The key

The key is kept in keys/<name>.key in Torrenta’s folder, readable by you alone, on this computer only: it never syncs. Anyone with the file can publish versions under your link, and without it there will be no more versions, ever, so keep a copy somewhere safe.

Items fade from the DHT after a couple of hours, so while Torrenta runs it puts the link back every hour (the first a minute after a start) when it is no longer found there. If no DHT node took the link when you created it, the dialog says so, and Torrenta keeps trying every hour.

Limits

Following and publishing need libtorrent and its DHT: with a Transmission daemon as the engine, New Version… and Copy Updatable Link are hidden.