All of the supported BitTorrent applications have a web interface or web-based API that allow other applications to communicate with it. More specifically, it supports the JSON-RPC or XML-RPC protocol (or some custom flavour) for easy communication over the internet.

Transdroid uses the exposed Transmission API, that of µTorrent, Vuze’s XML over HTTP plug-in, rTorrent with XML-RPC support and the JSON API of Deluge as well. Via asynchronous HTTP web requests and responses, you can fully control the daemons.

Interested in supporting all these torrent client in your Java application? Transdroid is open-source and the daemon adapters can be extracted from it’s source code easily.

The in-app search is build using the same approach. isoHunt exposes a JSON-RPC API as well while BTJunkie and Mininova have custom RSS feeds per search.

Transdroid is open source software and complete free. The code is managed at Google Code and can be browsed. Any bug or feature requests can be reported in the issue tracker over there.