[Zope3-dev] Interfaces and Schemas

[Shane Hathaway]

Steve Waterbury wrote:
> See above -- I meant "equal" in status, although distinct
> in semantics.  Basically, a schema is a "content model"
> (a.k.a., an information model); an interface is an API.
> They are different in the same way that information
> modeling is different from object modeling (e.g.,
> E-R modeling vs. UML modeling), although in first-order
> cases they can have large overlaps or even be identical.

Steve,

I would be very interested in learning about "second-order" cases.  I 
think you might have some useful insights, but I don't know what yet.

One thing that occurred to me recently is that there is a major 
distinction between APIs and configuration interfaces.  APIs are most 
often represented using methods while configuration interfaces are 
better represented using fields.  I think that APIs should almost always 
be defined independently of configuration interfaces.  For example, if 
there were a Zope-like "catalog" service, its API would provide methods 
for adding objects and searching, but no methods for changing or reading 
the configured indexes.  Changing or reading its indexes would be 
implemented through its configuration interface instead.

Shane