[Zope3-dev] Re: Some thoughts on Zope 3, Zope 3 applications, and Zope 3 instances

[Martijn Faassen]

Jim Fulton wrote:
[snip]
> The current Zope 3 distribution also contains an application that 
> resembles Zope 2 in many ways. There is an object tree and a Zope 
> Management Interface.  At least up to now, when you install a Zope 3 
> distribution, you get an application that you can run out of the box, 
> for whatever that's worth.  In this document, I'll call this application 
> the the Object Filing System (OFS).
>
> I've found the OFS to be useful when developing Zope 3 itself.  The OFS 
> was really the first application developed with Zope 3.  There are also 
> certain kinds of applications that can use the OFS as a starting point.  
> We've built content-management systems that reuse much of it.  In the 
> later case, we've used it less as an application than as a library.  
> It's not obvious to me that that the OFS has much value as an 
> application in it's current form.

In development I've typically used bits and pieces from the OFS as a 
library. That is, I used the OFS components but didn't care much about 
the ZMI user interface on top of it. I'm not sure whether your OFS is my 
ZMI, but I'll talk about the ZMI here in the hope it's close enough to 
what you mean. If not I hope my discussion is valuable in its own right. :)

I do think there is room for a management interface that allows you to 
inspect object state and do some simple configuration, but it should be 
focused narrowly and not aim to be an TTW application development 
environment or content management system or a reusable user interface 
framework. We are hoping to develop a management interface like that for 
Grok at some point (I'm currently in Germany for grok sprint 2).

[snip]

> My current thinking, FWIW:
> 
> It's not clear to me that the Zope 3 application we now distribute has 
> much value.  I'd be interested to hear other people's thoughts on this.  
> I'd like to see some popular Zope 3 applicaton or applications that 
> people download and use to get excited about Zope 3.  I don't know if 
> anyone is developing something like that. I hope they are.  I don't 
> think anybody is trying to turn the existing OFS into an application 
> like that.

I'd like to rephrase this and say I don't think (or hope) that someone 
is trying to turn the existing Zope 3 ZMI into an application like that. 
I like having simple base classes like Folder and File around that I can 
reuse or inherit from. We're hoping to supply these with Grok though. 
Something OFS-like and simple would have its place in my view of the 
terminology. :)

While I fully support Zope 3 becoming a library and toolbox of reusable 
bits, I also want to emphasize that it's very important for Zope 3 to 
have obvious ways to do things, preferably one obvious way to do it. Of 
course the underlying system should be flexible, but the code that 
people will be reading should be clear and easy to understand. This is 
where popular Zope 3-based applications come in: they serve as sample 
code for the applications following them (no matter whether they want to 
be sample code or not).

[snip]
> In summary, I'm seeing Zope 3 applications as separate entities from the 
> OFS.  The OFS application isn't something we'll use directlty.  
> Instances will be instances of our applications, not of Zope 3.

I think this pattern is a good approach. I do think that it is valuable 
to emphasize that each instance has some common features: you could for 
instance support a debugging or management UI that can be optionally 
enabled for each of them. This allows for commonality and also the 
feeling that people get more out of the box than a lot of tools they may 
not know how to apply effectively.

> None of this should be taken as any sort of edict.  I'm also not trying 
> to name anything. While I'd love to spur discussion, I hope not to start 
> any arguments. :)

The current ZMI is currently doing some things for us (however badly), 
so we should analyze what it does:

* first user experience. I install zope 3 and can vaguely click around 
the ZMI. Not much, but at least I have the feeling what I installed 
works and is doing obscure things.

* it is a user interface that helps with installing applications. 
Multiple instances of an application may be deployed under the same port 
number. I think this is a valuable feature, and allows the possibility 
for multiple cooperating applications without having to open new ports 
for each of them. You can use the ZMI to install multiple Document 
Library instances, for instance.

* it's an introspection and debugging interface. My application is 
broken during development and deployment and I can go into the ZMI and 
see what's wrong. I can look at various local configuration settings.

* it can be a configuration interface. Not only complicated stuff like 
installing local utilities, which I hope can move mostly to declarative 
code instead, but also simple stuff like which exceptions are logged can 
be configured.

What else?

We should figure out what we want to (and can) keep when we dump the ZMI 
as it is now, and how.

Regards,

Martijn