How To Write Your Own BitTorrent Client By Using BT Library!

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Hello everyone! In this article, we will talk about what the Bt library is and why it is worthwhile to have it in mind if BitTorrent is planned to solve some problems. Then, as a demonstration of the basic functions and the main API, we implement the simplest console torrent client.

Distinctive features of Bt

Bt is a modern full-featured implementation of the BitTorrent protocol on Java 8. Compared with existing open-source analogs, Bt has the following advantages:

• Modular design, which makes it easy to refine and expand. The architecture is based on the Guice IoC container and the standard java.util.ServiceLoader mechanism. Guice provides a transparent addition of new components and a redefinition of standard services, and ServiceLoader makes it extremely easy to assemble a client consisting of several modules, incl. located in a different jar’ah.
• The absence of binding to the mechanism of data storage. Standard storage assumes the existence of a file system, but, thanks to the use of the interface java.nio.file.Path supports including. and in-memory file systems, such as Jimfs.
• Full support for the mechanism for extending the standard protocol with your own message types, which can be useful in the case of developing a non-standard client for specific needs.
• Relatively low CPU and memory footprint and very fast performance, even with a large number of processed torrents and network connections, not least thanks to the use of NIO and a single-threaded kernel for sending and receiving messages (while alternative implementations for simplicity use a separate stream for each connection and blocking I/O).

 

The options required for the serious BitTorrent client options that are supported in Bt include:

• Extensive tuning and configuration options
• Integration with Mainline DHT
• Support for HTTP and UDP trackers, incl. multitrackers and private trackers
• Search for local peers through multicast
• Exchange of information about feasts with other participants in the distribution
• Obfuscation of traffic using session keys and asymmetric encryption
• Parallel upload/distribution of several torrents
• Selective downloading of individual files
• And finally, work with magnet-references. To download a torrent, just specify its unique identifier in the form of a link:

magnet:?xt=urn:btih:af0d9aa01a9ae123a73802cfa58ccaf355eb19f1

Creating the simplest command-line client

For the sake of minimizing body movements and avoiding unnecessary errors, we recommend not trying to reproduce the project code in the text of the article, but immediately download the finished project with GitHub.

 

If interested, please read the entire tutorial < here >.