CT: What determines what portions
remain in the commercial application and what gets fed back to the
sendmail open source?
Olsen: We do, and it's an interesting problem.
Let me tell you how we deal with it.
The hybrid model deals with this using fairly traditional
product line thinking. In the open source we use product lines for
the development community. The commercial line is a product line
for people who use this to run businesses. We've got some real
smart product managers who argue about what goes in which product
line. That's not unique. In fact, any company that has multiple
product lines has this problem. Basically, we argue on the basis of
what the target users in these segments need.
Now, there are a couple of other rules. Anything that has to do
with standards has to go everywhere, of course. Anything that's
contributed by the community of open source users must be fed back
to that community as part of the open source. We sometimes put some
of the commercial innovations into the open source because we want
to spur open source development. For instance, the APIs are
developed commercially to do very efficient content filtering. We
published that in the open source, and that encourages the
development community to come up with new, imaginative ways to do
We've also developed commercial filters -- both on a consulting
basis and on a commercial product basis -- that are part of the
commercial product line. But they can be plugged into the open
source because the APIs are compatible.