Monday 12 January 2004

Pic of the day: Picture from inspirational anime Naruto.

Super-seed

No, I am not referring to Larry Niven's gross essay "Man of steel, woman of Kleenex" or anything in that direction. The expression "super-seed" comes from a new and improved BitTorrent client.

BitTorrent is a system for file sharing. It is somewhat more explicit and less nebulous than Kazaa, Gnutella and the other typical piracy tools. Although it certainly can be, and is, used for piracy. Whether that is what I use it for is a matter of definition, I guess.

I don't download (or upload) music. As for movies, I only traffic in fansubbed anime. That is to say, Japanese cartoons that have been fitted with English subtext by volunteers, since the movies are not available in English otherwise. As such there is presumably no theft involved, although it does break the copyright laws of several countries. There is of course the risk that when an official translation to English comes, people won't buy it since they already have the fansub. On the other hand, there would hardly have been a market for anime or manga (Japanese comics) at all if not for the amateur translations that brought this art form to the West. And all the fansub groups I download from have a policy of stopping distribution as soon as a license is announced in any English speaking country. I follow the same policy, even though DVDs from America cannot be played on European players.

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BitTorrent was originally released as a tool for distributing software upgrades without investing in heavy server capacity. Ideal for smaller software firms. The principle is that while a client is downloading the file, he is simultaneously uploading it to other clients. There is a central tracker for each file (or folder) that is distributed. All seekers register with this tracker, which gives them the IP address of other seekers. Then there has to be a "seed", an original complete version of the file. The file is broken up in small pieces, which are uploaded separately. They are identified with a tag that lets the client put them back together in the proper order, and also check that they have not been damaged in transmission. Once you have received a piece of the file, the BT program automatically reports your success to the tracker. You will now be a seed for that piece, and other clients can get it from you instead of from the original seed. Thus the supply increases at the same speed as the demand.

Not all connections are created equal. Some have high-speed broadband, others have a crackling phone line. Many users have ADSL, as have I, and our download capacity is much higher than our upload capacity. That's just a property of ADSL. In addition, some people try to restrict their upload for various reasons. The result is that downloading the same file can go faster or slower depending on who you happen to connect to.

This is where the super-seed comes into play. If you are the one with the complete file, you can (in the new program) choose super-seed mode. This program will start by randomly uploading pieces of the file. If some of them are already uploaded, it will try to upload the least common pieces, those that exist on the fewest client computers. The super-seed notices who it uploads each piece to (the IP address, not the street address of course!) and then waits. When the piece is announced received from another client, it assumes that its client has passed it on, and will send another piece. You don't get a second piece of the file unless you pass on the first one. So people who for some reason choose to restrict upload will find their download fading as well.

In a typical swarm of BT clients there will be some that upload much faster than others. These already have a benefit in the original version of the program, but the super-seed will increase this benefit further, as they will more or less monopolize the original seed and get pieces before anyone else. They in turn work as distributors, amplifying the upload speed for the whole pool.

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Perhaps we should have something like this in "real life" too. Tax breaks for donations to charities is a beginning, I guess, but I wish there was something more we could to. I think if society was more transparent, people would be naturally rewarded in various ways for sharing with those who need it. It seems to me that much injustice and misappropriation of funds comes out of closed rooms, where deals are being made among "friends" who benefit from one another's patronage. If it become more clear who gave and who received, I am sure it would benefit us all.