CAMBRIDGE, ENGLAND - Researchers at Microsoft's (Profile, Products,
Articles) Cambridge, England, labs are developing a file-sharing
technology that they say could make it easier to distribute big files
such as films, television programs and software applications to
end-users over the Internet.
Code-named Avalanche, the technology is similar to existing
peer-to-peer (P-to-P) file swapping systems such as BitTorrent's, in
the sense that large files can be divided into many smaller pieces to
ease their distribution. End users request the file parts from other
users' hard drives and reassemble them to create the original file.
Such systems can scale well to serve millions of users, and reduce the
bandwidth and computing costs of sending content directly to users from
central servers. Some have also irritated publishers who complain the
services are used to share copyright works illegally.
The problem with existing systems, according to Microsoft, is that
people sometimes have wait a long time to receive the last, "rare"
pieces of a file. This is made worse when clients drop off line
unexpectedly and creates bottlenecks when only a few clients have files
that are in high demand.
Avalanche goes a long way to solving these problems, according to Peter
Key, joint head of the systems and networking group at Microsoft's
research labs in Cambridge, during an open day on Wednesday.
It does this by encoding the file pieces at the server with a special
algorithm before they are distributed. Each encoded piece contains
information about every other piece of the original file, so users
don't have to collect every last piece in order to reassemble the
whole, Key said.
"Each encoded piece has the 'DNA' of all pieces in the file," another
Microsoft researcher wrote. "A given encoded piece can be used by any
peer in place of any piece."
When PCs in the Avalanche network receive encoded files, they randomly
create new encoded files from the ones they have collected, and these
are sent to other peers. When a user receives enough encoded files,
they assemble them to make the original.
The system differs from BitTorrent's eponymous software in a few ways,
Key said. It does not depend on central servers, called "trackers," to
orchestrate the download. The Avalanche client on each PC shares the
files automatically among users; they do not look at other users' hard
drives to find what they want. And the system works well in smaller
networks, such as a corporate intranet, he said.
Perhaps more importantly for content creators, Microsoft claims its
system prevents users from redistributing copyright material, because
Avalanche will only forward files that have been signed by the
Microsoft has developed a prototype of Avalanche and is testing it by
using it to distribute software applications to several thousand of its
software beta testers, according to a research engineer demonstrating
the software in Cambridge. The company has distributed a 4GB
application in as little as a day, down from about two weeks when it
sends a program directly, he said.
The software may also be interesting to TV broadcasters and movie
studios. Microsoft has been in talks with both groups, and Avalanche
may be introduced to users in the U.K. as early as next year, he said.
The British Broadcasting Corporation (BBC) began testing a service last
month that lets people download TV and radio programs using a P-to-P
system from Kontiki (Profile, Products, Articles). It is not looking at
Avalanche currently, but will put the contract out for public tender
before launching the service, said Chris Charlton, a BBC spokesman.
The concept behind Avalanche is impressive, according to Mike Thompson,
principal research analyst with Butler Group, in Hull, England, who saw
the technology demonstrated. But it faces two problems of perception,
"Firstly, Avalanche is a mirror of P-to-P models that are coming under
scrutiny for allowing illegal distribution. I believe this idea of
'good' and 'bad' P-to-P for file-sharing of copyright material will
create a deal of confusion.
"Secondly, despite the 'pull' nature of the model and the security that
should allow only the file to be accessed, Microsoft has had issues
around security in the past -- IIS [Internet Information Server] being
the clearest example of a secure solution that wasn't. I think the
P-to-P network would be a prime target for the dissemination of
viruses, despite Microsoft's assurances that it is 'safe.'"
Still, Avalanche is "an excellent take on P-to-P," Thompson said.