There are a significant and growing number of people in group B.
Yup, that makes sense. Are these assumed to also be the folks who will try to make sure that new Z3 releases make it in to Z2 via Five? I guess what I'm driving at is that I'd hate to eventually have a very old version of Z3 sitting inside of Zope 2 due to insufficient bandwidth on the part of those developers to keep up with Z3 releases.
While it wouldn't be the end of the world or anything, I suspect some dependencies will inevitably creep into the Zope 2 core on Zope 3 packages, and maintaining an older codebase can be pretty painful. The testing requirements for making sure that changes that Z2 coders make to Z3 work both in Z2 and Z3 is a pretty high bar, just as vice versa. In the past, I've seen efforts like this turn into an effective fork as a result.
It won't turn into a fork. Right now there is a lot of discussion going on about the 'right' way to manage Z3 releases -- we'll need to decide on a Z2 release policy that takes that into account. I think the goal for Z2 will be to include the latest stable z3 possible. Some have suggested synchronizing the releases - that may be the way to go if it isnt impractical from an operational point of view. In any case, the goal is to gradually (but consistently!) make more and more Z3 functionality available to Z2 developers in future Z2 releases, based on the most stable Z3 baseline possible.
Please correct me if I'm wrong here but I get the sense that Five is less of a "migration path" from Z2 to Z3 than a way to integrate Z3 technologies (like views and adapters) into Z2 right now. Obviously allowing Z2 developers to use these things will give them a some needed familiarity with Z3 if they decide to switch but the migration path to "straight Z3" will always be more or less a rewrite, no?
It is definitely a migration path. Lets say you have an application based on Z3 with 10 (logical) components. You couldn't feasibly rewrite all of it at once to use Z3. As of 2.8, you'll be able to add functionality to your application using adapters, views, etc. So for V.Next of your app, maybe you are able to port 2 existing components and add 1 new one. For V.Next.Next, you add 2 more and port 2 more. At some point, it *will* be feasible to jump to Z3 with a minmal effort, since you've been able to port your application to components over time.
I *do* expect these (good) questions to recur in future Z2 releases, as integration and ability to use Z3 technologies increases, but we'll have plenty of time to work those out.
For now, I think it is a huge win to make some Z3 avenues available to people who want to use them, without forcing everyone to drink the kool-aid at once ;)
Yup... I'm still a bit skeptical but if other folks are committed to maintenance I'd be less so.
Skepticism is healthy, but if it's any consolation, almost everyone involved in this effort has very real 'skin in the game' in terms of existing Zope2 investments. I think that will do a great deal to ensure that the decisions made for future 2.x work are sane and take real-world concerns into account. Brian Lloyd brian@zope.com V.P. Engineering 540.361.1716 Zope Corporation http://www.zope.com