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What is
BitTorrent? BitTorrent is a protocol designed for
transferring files. It is peer-to-peer in nature, as users connect to each other
directly to send and receive portions of the file. However, there is a central
server (called a tracker) which coordinates the action of all such peers. The
tracker only manages connections, it does not have any knowledge of the contents
of the files being distributed, and therefore a large number of users can be
supported with relatively limited tracker bandwidth. The key philosophy of
BitTorrent is that users should upload (transmit outbound) at the same time they
are downloading (receiving inbound.) In this manner, network bandwidth is
utilized as efficiently as possible. BitTorrent is designed to work better as
the number of people interested in a certain file increases, in contrast to
other file transfer protocols.
BitTorrent is a free speech tool. You have something terrific to publish -- a
large music or video file, software or anything else that many people would like
to have. But the more popular your file becomes, the more you are punished by
soaring bandwidth costs. If your file becomes phenomenally successful and a
flash crowd of hundreds or thousands try to get it at once, your server simply
crashes and no one gets it.
The key to scaleable and robust distribution is cooperation. With BitTorrent,
those who get your file tap into their upload capacity to give the file to
others at the same time. Those that provide the most to others get the best
treatment in return. ("Give and we shall receive!")
Cooperative distribution can grow almost without limit, because each new
participant brings not only demand, but also supply. Instead of a vicious cycle,
popularity creates a virtuous circle. And because each new participant brings
new resources to the distribution, you get limitless scalability for a nearly
fixed cost.
BitTorrent is not just a concept, but has an easy-to-use implementation capable
of swarming downloads across unreliable networks. BitTorrent has been embraced
by numerous publishers to distribute to millions of users.
Official BitTorrent site :
http://www.bittorrent.com/
Where can I download the BitTorrent program?
There are several choices here, because unlike some peer to peer applications
(such as Kazaa), the BitTorrent implementation is open source. This means that
programmers are free to take the source code to the program and modify it, if
they feel there is something they'd like to change. Here are the various
clients:
Azureus
- (Recommended Client) - A very nice Java client that incorporates a
full-featured GUI with extensive visualizations/statistics about the transfer.
You will need the 1.4 JRE installed to run this, which can be obtained from this
link.
See also:
Screen shots.
The Shad0w's experimental client
- This client incorporates the codebase of the official version as well as all
the improvements of the experimental version, below. Additionally, there are
some misc. bug fixes, improvements from the latest development CVS sources, a
user preferences feature that remembers its settings, and more. I highly
recommend this version!
(alternate) (alternate
2)
Official client - This is the "official" client in that it is the latest
supported version from Bram Cohen, architect of BitTorrent. It has the fewest
features of all the clients, and releases are much more conservative than the
experimental versions. Use this if you want stability but don't need any of the
common features of the other clients, such as upload rate limiting. See also:
(CVS view),
Sourceforge page.
I've installed BitTorrent, now what? There's no program
to run!
BitTorrent is not like other peer-to-peer applications (such as Winmx, Kazaa,
Gnutella, etc.) in that it does not have its own "universe." Put another way, BT
lives on top of the Web, which means that all of the searching/listing of
available files is done on the web. When you find a file you want to download,
you click on it and the BitTorrent client program will run and ask you where to
put it, and then start downloading. See the links section for some starting
points on the web if you're new.
I just installed BitTorrent but whenever I click on a
link I just get a small file and nothing happens?
Try closing and restarting your web browser. When BitTorrent installs, it
registers a new MIME-Type (application/x-bittorrent) and this change will not
take effect until the next time the web browser is opened.
What do all these words mean? (seeding, uploading, share
rating, etc.)
Here is a brief list of words associated with BitTorrent and their meanings.
torrent: Usually this refers to the small metadata
file you receive from the web server (the one that ends in .torrent.)
Metadata: here means that the file contains
information about the data you want to download, not
the data itself. This is what is sent to your computer when you click on a
download link on a website. You can also save the torrent file to your local
system, and then click on it to open the BitTorrent download. This is useful if
you want to be able to re-open the torrent later on without having to find the
link again. In some uses, it can also refer to everything associated with a
certain file available with BitTorrent. For example, someone might say "I
downloaded that torrent" or "that server has a lot of good torrents", meaning
there are lots of good files available via BitTorrent on that server.
peer: A peer is another computer on the internet
that you connect to and transfer data. Generally a peer does not have the
complete file, otherwise it would be called a seed. Some people also refer to
peers as leeches, to distinguish them from those generous folks who have
completed their download and continue to leave the client running and act as a
seed.
seed: A computer that has a complete copy of a
certain torrent. Once your client finishes downloading, it will remain open
until you click the Finish button (or otherwise close it.) This is known as
being a seed or seeding. You can also start a BT client with a complete file,
and once BT has checked the file it will connect and seed the file to others.
Generally, it's considered good manners to continue seeding a file after you
have finished downloading, to help out others. Also, when a new torrent is
posted to a tracker, someone must seed it in order for it to be available to
others. Remember, the tracker doesn't know anything of the actual
contents of a file, so it's important to follow
through and seed a file if you upload the torrent to a tracker.
tracker: A server on the Internet that acts to
coordinate the action of BitTorrent clients. When you open a torrent, your
machine contacts the tracker and asks for a list of peers to contact.
Periodically throughout the transfer, your machine will check in with the
tracker, telling it how much you've downloaded and uploaded, how much you have
left before finishing, and the state you're in (starting, finished download,
stopping.) If a tracker is down and you try to open a torrent, you will be
unable to connect. If a tracker goes down during a
torrent (i.e., you have already connected at some point and are already talking
to peers), you will be able to continue transferring with those peers, but no
new peers will be able to contact you. Often tracker errors are temporary, so
the best thing to do is just wait and leave the client open to continue trying.
downloading: Receiving data FROM another computer.
uploading: Sending data TO another computer.
share rating: If you are using the experimental
client with the stats-patch, you will see a share rating displayed on the GUI
panel. This is simply the ratio of your amount uploaded divided by your amount
downloaded. The amounts used are for the current session only, not over the
history of the file. If you achieve a share ratio of 1.0, that would mean you've
uploaded as much as you've downloaded. The higher the number, the more you have
contributed. If you see a share ratio of "oo", this means infinity, which will
happen if you open a BT client with a complete file (i.e., you seed the file.)
In this case you download nothing since you have the full file, and so anything
you send will cause the ratio to reach infinity. Note: The share rating is just
a number that is displayed for your convenience. It does not directly affect any
aspect of the client at all. In general, out of courtesy to others you should
strive to keep this ratio as high as possible, of course. |
