Re: How can I lock a record using php-ldap?

[Jon Roberts <jon@mentata.com>]

Jim C wrote:

> I need to be able to lock an attribute, series of entries or one 
> record and then perform several actions and then unlock the 
> attribute.  How can this be done?
>
> Not being able to do this would constitute a bug because it means that 
> there will always be problems with race conditions between scripts. 
> This is easily proveable.

As people have already pointed out, LDAP is not a transactional database 
but is rather optimized for search and retrieval. This isn't a bug, it's 
a new and unwieldy requirement. I wouldn't expect it in an LDAP 
implementation anytime soon (if ever), so you need to consider 
addressing it at an application layer. This may be difficult using a 
scripting language like PHP, and I definitely don't recommend storing 
the highest uidNumber value in the directory database itself.

I've been considering this issue, and will probably be implementing a 
solution in my software (LDAPHttp) in the coming months as a "managed" 
identifier attribute type. I use Java servlets, not PHP, so I can take 
advantage of synchronization and memory residence. I would use a single 
process for creating new entries. This process would internally deduce 
and store the highest uidNumber (or whatever) in memory. Upon each new 
creation, a synchronized block of code would increment the highest 
uidNumber and return it, thereby avoiding race conditions.

If there are other perspectives on how to do this, I'd be interested to 
hear them. While I don't think LDAP should match the RDBMS model 
function for function, managed identifiers would make a nice addition.

Jon Roberts
www.mentata.com