Re: Auto-Increment

[Jon Roberts <jon@mentata.com>]

Robert Canary wrote:
> Is it possible to create an auto-incrementing field in LDAP?  I would
> like to use it in my uidNumber field from the accoun schema. 
>
> It would certain be a wonderfull feature, IMHO.

As somebody already said, it isn't supported in OpenLDAP, but it can be 
accomplished at your application layer. I just released code that does 
exactly this with an OpenLDAP based weblog application:

http://www.mentata.com/ldaphttp/examples/gospel/jesusblog.htm

The relevant routine is in the file linked with "comment.java" and is 
called "getNextIdentifier". When new entries are created in a directory 
database with my software, I have a "preCreate" method that enables 
internal pre-processing, which for this object includes the creation of 
its identifier. Here I call this routine, which when it is first run 
will use a simple linear algorithm (I'm sure Howard et al could craft a 
better one) to determine the highest identifier value and store it. Any 
subsequent creations just increment and pull the next identifier value 
from memory. I do this in synchronized blocks to avoid the obvious race 
conditions.

New blog entries should be added to this example on a weekly basis, 
starting this weekend. I encourage you and anyone on this list to post 
your own comments to see this routine and OpenLDAP in action.

Jon Roberts
www.mentata.com