[Zope3-Users] Re: Zope3 with RDBMS (avoiding ZODB)?

[Philipp von Weitershausen]

Stefan Krumbiegel (Galileo Press) wrote:

[skipping questions I can't answer]

> 1. Is Zope3 already in use in productive environments? Where are they 
> (URLs)?

Sure, a lot of people on the zope3-users list are using Zope 3 in 
production. In particular, many Zope solution providers like Zope Corp, 
gocept, Infrae, Lovely Systems, etc. are using Zope 3 in production with 
several projects and have open-source'd a lot of their code (mostly at 
svn.zope.org). Canonical is using Zope 3 for Launchpad 
(https://launchpad.net). Schooltool is written in Zope 3 as well 
(http://schooltool.org).

> Now, where should we start with it in Zope3 to connect it to an RDBMS?

Using an object-relational mapper such as SQLObject or SQLAlchemy. Then 
you either write the bridging code from Zope to those yourself (hook the 
two transaction systems together, etc.), or you use one of the 
already-existing bridging solutions, sqlos 
(http://codespeak.net/z3/sqlos/) or z3c.zalchemy 
(http://svn.zope.org/z3c.zalchemy/).

> 3.2 sqlos - SQLObject Support package (http://codespeak.net/z3/sqlos/):
> Is it stable? Has someone experiences with it?
> In http://mail.zope.org/pipermail/zope3-users/2006-January/001797.html
> Stephan Richter says: "On the other hand, not many people use sqlos, so
> it might not be as supported as you wish it would be." Is that still right?

I know of a larger project that uses sqlos in production 
(http://www.enfoldsystems.com/Products/Open/SIP). I know that there are 
people using and maintaining sqlos, but I can't say to which degree. 
Best is you ask specific questions on the sqlos mailinglist 
(http://codespeak.net/mailman/listinfo/z3-sqlos).

> 4. Has anybody practical experience and hints with Zope3 and RDBMS?

Sure. Do you want me to write them all down now? Please be specific or 
come to one of my trainings :).

> 5. The ZMI: In Zope2 we never used it. Do we need the ZMI in Zope 3
> just if we will not use the ZODB for storing our content objects but
> an RDBMS instead. According to 'Web Component Development with Zope
> 3' by Philipp von Weiterhausen the ZMI is used to manage content
> objects stored in the ZODB, so our assumption is, if we do not store
> them in the ZODB, we do not need the ZMI. Is that right or do we need
> the ZMI for anything else? Do we need ZMI in Zope3 for administration
> or can we do that with scripts etc.?

The Zope 3 "ZMI" can be seen as an example application for Zope 3. It's 
absolutely not necessary and I think very few people are using even the 
smallest parts. To cut a long answer short: no, you absolutely don't 
need the ZMI. In fact, disable zope.app.rotterdam in your Zope 3 
instance configuration and the ZMI is gone (at least the skin).

> 6. Last but not least two quotes from the zope3-dev mailinglist
> (http://mail.zope.org/pipermail/zope3-dev/2006-February/018217.html):
>> >Shane Hathaway wrote:
>>> >> It could
>>> >> turn out that people who don't want ZODB really shouldn't use Zope at
>>> >> all.
>> >This has been the case in my experience...
>> >Chris Withers
> ...
> Discussion 'Zope 3 without ZODB' in the zope3-dev mailinglist
> (http://www.mail-archive.com/zope3-dev@zope.org/msg07517.html): 
> 
>> >... I expect that such an application would look a lot like
>> >applications built with other web frameworks.
>> >Jim Fulton
> 
> What do you say about that? Does that mean that we should definitively
> not use Zope3 if we don't want to use the ZODB but our RDBMS instead?

Jim's quote is out of context, I believe. He's talking about 
applications that don't use object publishing. You can still use object 
publishing with RDBMS.

I think people should consider Zope 3 if...

* they like the idea of object publishing (=URLs are broken into parts 
which correspond to individual objects)

* they like the idea of separate, invidually testable and replaceable 
components

* they like the ability to reuse components built by the community 
and/or to make their components available to the community for reuse


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