CMFUid Readme

    CMFUid introduces a unique id implementation to the CMF 1.5.0 and newer.
    
    Implementation
    
        The supplied tools attach the unique ids to the objects. The objects
        do not have to be aware of unique ids.
        
        The current implementation depends on the portal catalog to find an 
        object of a given unique id. The interfaces do not imply the use
        of the catalog (except the IUniqueIdBrainQuery).
        
        Which Tool does What?
        
            The 'portal_uidgenerator' tools responsibility is to generate 
            unique ids. The 'portal_uidannotation' tool is responsible to 
            attach unique ids to a content object, and enforce rules about
            what happens on object move/create/delete. The 'portal_uidhandler' 
            manages registering and accessing unique ids. 
            
            This design was chosen to allow users replacing only parts of
            the functionality without having to understand the whole thing.
        
        Unique Id API
        
            'portal_uidhandler' implementing 'IUniqueIdHandler' is the main 
            API for playing with unique ids.
        
    Dependencies
    
        Object lookup by unique id depends on CMFCore (especially on 
        portal_catalog). 
    
    Usage
    
        'portal_uidhandler' fully implements IUniqueIdHandler (IUniqueIdSet
        for registering/unregistering unique ids, IUniqueIdQuery for queries
        and IUniqueIdBrainQuery for more efficient queries by returning 
        catalog brains instead of objects).
        
        The current implementation of get/queryBrain and get/queryObject 
        do not return invisible objects (and brains of invisible objects).
        By invisible objects, we mean objects that would be filtered out
        by portal_catalog.searchResults due to expiry/effective date and/or
        user roles.
        
        It is often necessary to avoid this filtering in an application.
        To do this, use the unrestrictedGet/QueryBrain and
        unrestrictedGet/QueryObject as this will avoid 'None' results.

        Have a look at the interfaces.
        
        CMFUid's functionality is used by CMFDefault's favorite content type 
        to follow linked objects. The favorite content type works as before if 
        CMFUid is not installed. 
        
        See 'CMFDefault.Favorite.Favorite'.
    
    gregweb/2004-08-05

UPDATE 2007-03-30
=================

The annotation code has been updated to use events for assigning/removing 
uids.  The settings for this live in the portal_uidannotation tool.

The default behaviour is:

 - uids are NOT assigned when an object is created
   (it is assumed that other code is responsible for this)

 - when an object is moved, a UID is not changed

 - when an object is imported, any EXISTING UID is removed
   (this can be controlled via the 'remove_on_add' property)

 - when an object is copied, any EXISTING UID is removed
   (this can be controlled via the 'remove_on_clone' property)

A more natural behaviour is for UIDs to be assigned automatically on 
creation.  To enable this feature:

 - tick the 'assign UIDs on add' tickbox
   (uids will now be assigned when content is added or imported and any
   EXISTING uid will be replaced)

 - tick the 'assign UIDs on copy' tickbox
   (objects will get a NEW uid when they are copied which will replace 
   any EXISTING uid)

In order to preserve the original behaviour of the tool, automatic 
assignment of uids is NOT enabled by default - it must be turned on in 
the uidannotation tool.

The behaviour is hooked in based on object creating/deletion/move events
for any IContentish objects.  The event handlers live in the 
UniqueIdAnnotation tool.


