Interview with Bram Cohen, developer of BitTorrent
Well there's is the universe which did happen and the universe which should have happened,
and pretty much everyone seems to agree that in the universe which should have happened,
BitTorrent was written by some venture capital backed company
which then got sued and kinda sort of acquired after getting sued into oblivion
and the CEO having a scare of almost having been
thrown in prison, or actually being thrown in prison.
Of course in the universe which actually happened,
- which doesn't really make any sense so it isn't really worth talking about.
In the universe which actually happened, BitTorrent was written by some guy
in his living room who was living off of credit cards and became explosively huge,
prior to taking any investment whatsoever.
And then the person who wrote it somehow wound up working with Hollywood.
And running a very legal business without any legally scary situations.
When you have television or radio and by that I mean television over the airwaves,
It's kinda like someone is screaming really really loudly and everyone else can listen.
And so anyone who wants to can tune in
Now this is not very efficient from an energy standpoint
and it involves some very very loud screaming.
It is highly effective at broadcasting signals to space aliens.
If there were any aliens hanging out around earth in the 1900s,
they'd have had a very very easy time watching television.
And getting a good look at our culture that way,
because that's where most of the signal was going, was out into space.
The internet doesn't work that way - on the internet
you have all these machines which are connected to the net
and you can send a message to anyone else on the net,
but it goes to just them - there's no broadcast concept there.
So there's this question of how do you make broadcasting work?
Unfortunately broadcasting can be rather difficult in that if you have something that's very popular
and very large and very high quality, it can become very expensive to distribute it.
It becomes expensive to be popular. With broadcast over the airwaves this doesn't happen,
You're screaming loud enough, everybody can hear you - not a problem.
On the internet it's a huge problem so BitTorrent was based
on this very fundamental calculation of well if you're sending out something,
and everyone wants the same thing, they can just send it to each other,
So there's this logistical problem of how to make that happen,
so I figured out how to make it happen.
Well the basic problem is a pretty simple one,
there's plenty of upload capacity out there not being used how do we use it?
So that's a trivial calculation on its own the problem is,
these are what you call low quality resources.
They're peers, they're untrusted, they are of unknown potential transfer rate
they're not of terribly good transfer rate to begin with and they're not very coordinated.
This isn't really so much of a problem of make something that works,
so much as make something that works reliably,
that can handle the fact that peers just sort of disappear and never come back again.
When I started working on it there was a bunch of people working on very much the same thing.
I decided on an approach that was actually much, much more ambitious
than a lot of the things that had been successful up until that time.
In that you when you're distributing something on the internet,
if you're doing it via HTTP, you kinda don't want everyone
to come and download the same thing at the same time.
You want nice small things that are distributed around when people download them.
and this is good for making it so you don't have too much load on the one central server,
and I went and did this calculation and figured, well no, I want to do the exact opposite thing.
I want everyone downloading the same thing at the same time.
Because if, and this at the time this was a pretty big if, if you can get a handle
on all the difficult logistical problems of making it actually happen,
then you can make it so that the initial place only has to upload one copy
of the whole thing and everything else will be distributed between peers
and you actually get maximum efficiency in the very situation you were trying to avoid
when you were doing everything via HTTP.
So in that sense I was being rather ambitious although other people were working on the same problem.
The difference was in terms of approach, that I came up with an architecture
which was designed first around reliability and efficiency
- in fact only reliability and efficiency- it's an utterly bizarre architecture
unless you consider it from the point of view of ok...
first thing, let's just assume that peers are unreliable
that we don't know what transfer rates are
that peers are untrusted and tend to go away
and then, out of what's left, how do we make something work
other people were trying the tree-based architectures, which proved not to work
but the reasons why are very much centered around reliability,
and are not obvious unless you've done some networking and know that just...
peers go away and never come back
DRM has a lot of political momentum right now
it's just like if you're putting content up online you have to have DRM and...
whether this is psychological, whether technicals are saying it,
whether lawyers are saying it, whether just collectively everybody feels
that somebody must be saying it, so you have to speak in one voice demanding it...
... is a little unclear, and varies from place to place
When you go to the movie theatre you pay
when you get a DVD you pay, when you rent a DVD you pay
there are a few things going on
one of the big things is what people associate with their home experience is watching television
You turn on the television and then you watch,
and people are rather disinclined
in some ways
paying for something to watch at home
they want to just have ads and watch it
by analogy with television
another thing that happens is that people are leery
frequently leery of paying for anything online
just putting in a credit card number,
because credit cards are so fundamentally insecure
makes people very nervous, they don't want to do that,
and it's an annoying process entering in your credit card number.
Now the ridiculous insecurity of credit card numbers has a lot to do with
with the ridiculous way banks work in the United States
where things are big and bloated and poorly done technologically
and there's very little if any incentive to fix it.
I would say that people are a little used to now,
when they download videos from the net, not paying for it,
it's just what they've been doing,
the paying for it model just hasn't been there!
So people just habitually aren't very used to paying for things.
At a certain point when you get down to what's termed level of cost
the actual price being charged is de minimis,
whether that's a dollar, or ten cents or one cent.
it's a little hard to say.
But at some point the actual price paid ceases to be a concern.
and that's for extremely popular content
isn't very de minimis
when you multiply it over the number of people who are paying it
that's effectively what advertising online winds up being
the monetization on it is small.
Generally speaking a penny per impression,
but winds up adding up in the end.
The question there is what is the form of that monetization?
Is it via advertising, which people are implicitly paying for in some way,
Is it explicitly paying where there is this usability issue of making the payment,
and the concern about fraudulent charges happening when this payment is happening
concerns about incentivizing spam, bladibladibla...
So at a certain level
there's the cost of the distribution and there's the value gotten from the thing
and if the cost
is some very small fraction of the value gotten from the thing
people cease to pay any attention to it whatsoever!
And the question then becomes what is the form of the payment.
Advertising is certainly a compelling model
in that it's very very simple,
Whenever you have payment going through a distributor
there's the whole issue of making the payment happen
both in terms of authorizing charges and redistributing the money
and it has to somehow hook into the payment system,
and advertising is somewhat inefficient
in that it implicitly hooks into the payment system
via some complicated route of people watching the advertising
doing something eventually, somewhere out there,
But it's much much simpler in general,
a more straightforward way of doing things.