BioTorrents
PLoS ONE | www.plosone.org 2 April 2010 | Volume 5 | Issue 4 | e10071

file transfers increases, and thus scales indefinitely. The end result is
faster transfer times, less bandwidth requirements from a single
source, and decentralization of the data.
Torrent files have been hosted on numerous websites and in
theory scientific data can be currently transferred using any one of
these BitTorrent trackers. However, many of these websites
contain materials that violate copyright laws and are prone to
being shut down due to copyright infringement. In addition, the
vast majority of data on these trackers is non-science related and
makes searching or browsing for legitimate scientific data nearly
impossible. Therefore, to improve upon the open sharing of
scientific data we created BioTorrents, a legal BitTorrent tracker
that hosts scientific data and software.
Results
Tracker and Reliability of Service
The most basic requirement of any torrent server software is the
actual ‘‘tracker’’ that individual torrent clients interact with to
obtain information about where to download pieces of data for a
particular torrent. In order to minimize any possible transfer
disruptions arising from the BioTorrents tracker not being
accessible, a secondary tracker is added automatically to all new
torrents uploaded to BioTorrents. Currently this backup tracker is
set to use the Open BitTorrent Tracker (http://openbittorrent.
com/). Also, many BitTorrent clients support a distributed hash
table (DHT) for peer discovery, which often allows data transfer to
continue in the absence of a tracker, further enhancing the
reliability over traditional client-server file transfers.
Obtaining Data
In addition to the basic tracker, BioTorrents has several features
supporting the finding, sharing, and commenting of torrents.
Relevant torrents can be found by browsing categories (genomics,
transcriptomics, papers, etc.), license types (Public Domain,
Creative Commons, GNU General Public License, etc.) and by
using the provided text search. Also, torrents are indexed by
Google (http://www.google.com) allowing users searching for
datasets, but unaware of BioTorrents existence, to be directed to
their availability on BioTorrents. Information about each dataset
on BioTorrents is supplied on a details page giving a description of
the data, number of files, date added, user name of the person who
created the dataset, and various other details including a link to the
actual torrent file. To begin downloading of a dataset, the user
downloads and opens the torrent file in the user’s previously
installed BitTorrent client software (Table 1). The user can then
control many aspects of their download (stopping, starting,
download limits, etc.) through their client software without any
further need to visit the BioTorrents webpage. The BitTorrent
client will automatically connect with other clients sharing the
same torrent and begin to download pieces in a non-random
order. The integrity of each data piece is verified using the original
file hash provided in the downloaded torrent ensuring that the
completed download is an exact copy. The BitTorrent client
contacts the BioTorrents tracker frequently (approximately every
30 minutes) to obtain the addresses of other clients and also to
report statistics of how much data they have downloaded and
uploaded. These statistics are linked to the user’s profile (default is
the guest account), to allow real-time display on BioTorrents of
who is sharing a particular dataset.
The choice of BitTorrent client will depend on the operating
system and options that the user requires. For example, some
BitTorrent clients (see Table 1) have a feature called Local Peer
Discovery (LPD), that searches for other computers sharing the
same data on their local area network (LAN), and allows rapid
direct transfer of data over the shared network instead of over the
internet. This situation may arise often in research institutions
where LANs are often quite large and multiple researchers are
working on similar datasets. Another significant feature of the
BitTorrent client, uTorrent, is the addition of a newly designed
transfer protocol called uTP[17], that is able to monitor and adapt
to network congestion by limiting its transfer speeds when other
network traffic is detected. This functionality is important for
system administrators and internet service providers (ISPs) that
Table 1. Comparison of several popular BitTorrent software clients and their features.
BitTorrent Client Name Operating System
1
Interface
2
RSS
3
LPD
4
DHT
5
Win. Mac. Linux GUI Web CLI
uTorrent X X X X X X X
Deluge X X X X X X X
Vuze X X X X X X X
Transmission X X X X X X
rTorrent X X X X
kTorrent X X X X X X X
1
Win:Microsoft Windows, Mac: Mac OSX.
2
GUI: Graphical User Interface, Web: built-in web server interface, CLI: command line interface.
3
RSS download can be obtained for all clients by using RSSDler (http://code.google.com/p/rssdler/).
4
LPD: Local Peer Discovery.
5
DHT: Distributed Hash Table.
doi:10.1371/journal.pone.0010071.t001
Figure 1. Illustration of differences between traditional and peer to peer file transfer protocols. A) Traditional file transfer protocols such
as HTTP and FTP use a single host for obtaining a dataset (grey filled black box), even though other computers contain the same file or partial copies
while downloading (partially filled black box). This can cause transfers to be slow due to bandwidth limitations or if the host fails. B) The peer-to-peer
file transfer protocol, BitTorrent, breaks up the dataset into small pieces (shown as pattern blocks within black box), and allows sharing among
computers with full copies or partial copies of the dataset. This allows faster transfer times and decentralization of the data.
doi:10.1371/journal.pone.0010071.g001
BioTorrents
PLoS ONE | www.plosone.org 3 April 2010 | Volume 5 | Issue 4 | e10071

may have previously attempted to block or hinder BitTorrent
activity due its bandwidth saturating effects.
Sharing Data
Sharing data on BioTorrents is a simple three step process. First,
the user creates a torrent file on their personal computer using the
same BitTorrent client software that is used for downloading
(Table 1). The only piece of information the user needs to create
the torrent, is the BioTorrents tracker announce URL which is
personalized for each user (see below), and is located on the
BioTorrents upload page. Second, this newly created torrent file is
uploaded on the ‘‘BioTorrents - Upload’’ page along with a user
description, category, and license type for the data. Third, the user
leaves their computer/server on with their BitTorrent client
running so that other users can download the data from them.
It should be noted that only users that have created a free
account with BioTorrents are able to upload new torrents. This is
to limit any possible spamming of the website as well as provide
accountability for the data being shared. BioTorrents enforces this
and tracks users by giving each user a passkey. This passkey is
automatically embedded within each torrent file that is down-
loaded from BioTorrents and is appended to the BioTorrents
tracker’s announce URL. Although, we would hope that most
users create an account on BioTorrents, we still allow anyone to
download torrents without doing so.
An alternative upload method is provided for more advanced
users that have many datasets to share and/or are sharing data
from a remote Linux based server. This method uses a Perl
(http://www.perl.org) script that takes the dataset to be shared as
input and returns a link to the dataset on BioTorrents along with
the torrent file; therefore, allowing torrents to be created for
numerous datasets automatically. This feature would be useful for
institutions or data providers that would like to add a BitTorrent
download option for their datasets.
Considering that many datasets in science are often updated,
BioTorrents allows torrents to be optionally grouped into versions.
This functionality allows improved browsing of BioTorrents by
providing links between torrents. More importantly, this versioning
classification allows users interested in certain software or datasets to
be notified via a Really Simple Syndication (RSS) feed that a new
version is available on BioTorrents. In addition, this RSS feed can be
used to obtain automated updates for datasets that are often
changing, such as genomic and protein databases. For example, a
user could copy the RSS feed for a dataset that is being updated often
on BioTorrents (weekly, monthly, etc.) into their BitTorrent RSS
capable client. When a new version is released on BioTorrents the
BitTorrent client automatically downloads the torrent file, checks to
see what parts of the data have changed, and downloads only pieces
that have been updated.
The speed and effectiveness of the BitTorrent protocol depends on
the number of peers; in particular, those peers that have a complete
copy of the file and can act as ‘‘seeds’’. Therefore, it is important that
individuals or institutions act as seeds to achieve full potential.
Currently, all newly added data is automatically downloaded and
shared from the BioTorrents server. This is to ensure that each
dataset always has at least one server available for downloading. As
the number of datasets and users of BioTorrents increases, and to
improve on transfer speeds on a geospatial scale (i.e. across countries
and continents), we would encourage other institutions to automat-
ically download and share all or some of the data on BioTorrents.
Discussion Forum, Comments, RSS, and FAQ
Any logged in BioTorrents user can write comments or
questions about a particular torrent directly on its details page.
This can provide useful feedback both to the creator of the
dataset as well as to other users downloading it. Alternatively,
researchers wanting to discuss more general questions about
BioTorrents, particular datasets, or science, can use the provided
‘‘BioTorrents - Forums’’. Comments and discussion posts can be
read by all visitors, but a free account is necessary to post to
either of these. Users that would like to be updated on newly
uploaded datasets can use the BioTorrents RSS web feed. The
RSS feeds can be configured for certain categories, license types,
users, and search terms, and can also be used with many
BitTorrent clients to automatically download all or some of the
datasets on BioTorrents without human intervention. Finally, the
‘‘BioTorrents – FAQ’’ (Frequently Asked Questions) page
provides users with information about BitTorrent technology
and general help for using BioTorrents for both downloading and
sharing of data.
Discussion
BitTorrent technology can supplement and extend current
methods for transferring and publishing of scientific data on
various scales. Large institutions and data repositories such as
GenBank[18], could offer their popular or larger datasets via
BioTorrents as an alternative method for download with minimal
effort. The amount of data being transferred by these large
institutions should not be underestimated. For example, in a single
month NCBI users downloaded the 1000 Genomes (8981 GB),
Bacteria Genomes (52 GB), Taxonomy (1GB), GenBank
(233 GB), and Blast Non-Redundant (NR) (3 GB) datasets;
100000, 30000, 15000, 10000, and 7000 times, respectively
(personal correspondence). If BitTorrent technology was imple-
mented for these datasets then the data supplier would benefit
from decreased bandwidth use, while researchers downloading the
data, especially those not on the same continent as the data
supplier, enjoy faster transfer times.
Small groups or individual researchers can also benefit from
using BioTorrents as their primary method for publishing data.
Although, these less popular datasets may not enjoy the same
speed benefits from using the BitTorrent protocol due to the lack
of data exchange among simultaneous downloads, the lower
barrier of entry to providing data compared with running a
personal web server, and the ability to operate behind routers
employing network address translation (NAT) makes the use of
BioTorrents for less popular datasets still beneficial. In addition,
BioTorrents allows researchers to make their data, software, and
analyses available instantly, without the requirement of an official
submission process or accompanying manuscript. This form of
data publishing allows open and rapid access to information that
would expedite science, especially for time-sensitive events such as
the recent outbreaks of influenza H1N1[19] or severe acute
respiratory syndrome (SARS)[20]. No matter what the circum-
stance, BioTorrents provides a useful resource for advancing the
sharing of open scientific information.
Implementation
The source code for BioTorrents.net was derived from the
TBDev.net (http://tbdev.net) GNU General Public Licensed
(GPL) project. The dynamic web pages are coded in PHP with
some features being implemented with JavaScript. All information,
including information about users, torrents, and discussion forums
are stored in a MySQL database. The original source code was
altered in various ways to allow easier use of BioTorrents by
scientists; the most significant being, that anyone can download
torrents without signing up for an account. In addition, torrents
BioTorrents
PLoS ONE | www.plosone.org 4 April 2010 | Volume 5 | Issue 4 | e10071

can be classified by various categories and license types, and
grouped with other alternative versions of torrents.
Availability
The BioTorrents web server along with the source code is
available freely under the GNU General Public License at http://
www.biotorrents.net.
Acknowledgments
The authors would like to thank Elizabeth Wilbanks and Aaron Darling for
reading and editing of the manuscript, and Mike Chelen and reviewer
Andrew Perry for suggesting several improvements for the BioTorrents
website.
Author Contributions
Conceived and designed the experiments: ML JAE. Performed the
experiments: ML. Wrote the paper: ML JAE.
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BioTorrents
PLoS ONE | www.plosone.org 5 April 2010 | Volume 5 | Issue 4 | e10071