Revolutionary protocol takes pain out of sharing large files

He wrote one of the most popular peer-to-peer networking applications in use today. He founded CodeCon, a self-described hacker’s conference. He never finished college. And by day, he writes networking software for Valve, publisher of such first-person shooter games as Half-Life and Counter-Strike. So does Bram Cohen consider himself a hacker?

“I’m a software developer,” Cohen says. “I write code. I’m productive that way. I really feel productive when I write code.”

So far, Cohen’s productivity has earned him accolades of which other developers can only dream. BitTorrent, the p-to-p file-transfer client he created, has taken the Internet by storm. BitTorrent clients that request the same file at the same time become a “swarm,” exchanging small pieces of the file with one another until every client has its own complete copy. In this way, BitTorrent takes some of the burden of hosting a file off of the server and moves it onto the clients, at the so-called network edge.

“It’s very, very aggressive about making the original source of a file not have to contribute much bandwidth at all. And it can scale to lots and lots of people and do so very quickly,” Cohen explains.

As a result, BitTorrent is rapidly becoming the preferred file transfer method for Linux vendors, which regularly publish large disk images as free downloads. Less welcome, however, are those who use the software to transfer illicit copies of copyrighted software, movies, and music. When asked if he feels he has a role in the current debate over intellectual property, Cohen sighs.

“I have no control over what people do with BitTorrent,” he explains. “The pirates who use BitTorrent, I could really, really do without. They’re not actually terribly supportive, even of me. They send me hate mail about how they’re uploading more than they’re downloading or pestering me about downloading this particular file.”

Nor is BitTorrent even Cohen’s sole focus. Besides CodeCon, another recent brainchild is Codeville, a version-control system that promises to solve some of the problems software developers encounter when they try to collaborate as a team.

What he plans for his next project might be is anyone’s guess. For now, he’s concentrating on a few planned updates.

“I don’t really consider myself a great visionary or anything,” Cohen says, with an uneasy laugh. “I’m not promising I’ll continue to make great advances in anything else in the future.” On that score, we’ll have to wait and see.