[Zope3-dev] Vocabularies, sources and relationships

[Santi Camps]

Hi all,

I'm just beginning to study Zope 3 (helped by the magnificent Philipp 
von Weitershausen's book).   I'm specially interested in the schema 
framework, and how it can be used to implement relationships between 
objects (if it can be used that way).  

I know that are proposals to replace vocabularies by sources, as 
described in the thread:
http://mail.zope.org/pipermail/zope3-dev/2004-September/012096.html

My doubs are: 

1) Are sources already implemented ?  If not, it will be ? 

2) In any case, are sources/vocabularies a good way to implement 
relationships between objects ?   I think an implementation of ISource 
and ITerm/s and so on could be writted providing values obtained from 
other objects, but I'm not sure what could happen with this relationship 
after created.   For instance, if the referenced object is deleted after 
that.    Is there any utilities in Zope 3 to take care about referential 
integrity between objects ?  

In Zope 2, I've added some Foreign Key capabilities to Z Catalogs, using 
one catalog per meta_type and overriding manage_beforeDelete and so on.  
So, for instance, a customer can't be deleted if it has some referencing 
invoice.  I just one to know if there are better ways to obtain the same 
result in Zope 3.

Thanks in advance

Santi Camps