[Zope3-dev] Twisted Publisher and Zope 2

[Martijn Faassen]

Chris Withers wrote:
> Stephan Richter wrote:
> 
>> I wonder whether a similar approach as the one taken for the Twisted 
>> server migration is possible. There, if you have an instance running 
>> on ZServer an upgrade will not cause the switch to Twisted, since your 
>> startup script still refers to the old server code. You explicitely 
>> have to change your startup script to start using Twisted.
> 
> 
> I think this is the way to go and a zope.conf option would be an ideal 
> way of making the choice...

I think it's rather too big a shift. I think that 'the old startup 
script still referring to the old server code' is definitely one that 
isn't appropriate for Zope 2; either the new server code is backwards 
compatible and almost everything will run perfectly, or the new code is 
not very backwards compatible and most Zope apps will break.

In the former case, hard to reach, I think we just want to upgrade 
everybody. In the latter case, possibly more likely, a zope.conf option 
is the least we can do. I'd be more in favor of a granular approach, 
where I can tell the system 'for this piece of content, use the Zope 2 
behavior, for that, the Zope 3 behavior'.

But I think we'll have to see which approach is best when there's actual 
experimental code; I guess only then we'll be able to judge how much of 
Zope 2 we can safely replace.

Regards,

Martijn